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Sample records for digital tomosynthesis mammography

  1. Digital Mammography and Digital Breast Tomosynthesis.

    PubMed

    Moseley, Tanya W

    2016-06-01

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

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

    SciTech Connect

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

    2006-05-15

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

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

    PubMed

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

    2016-04-01

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

  4. Three-dimensional Breast Imaging with Full Field Digital Mammography Tomosynthesis

    NASA Astrophysics Data System (ADS)

    Eberhard, Jeffrey W.

    2003-03-01

    Although conventional film-screen mammography is the clinical modality of choice for early detection of breast cancer, many cancers are missed because they are masked by radiographically dense fibroglandular breast tissue which may be overlying or surrounding the tumor. The superposition of 3D breast anatomy in a standard 2D x-ray projection is perhaps the most significant problem in mammography today. GE Global Research has developed a new 3D full field digital mammography tomosynthesis prototype system that directly addresses the superimposed tissue problem by enabling volumetric imaging of the breast. High performance digital detectors with low electronic noise and fast read-out times, new reconstruction algorithms customized for tomosynthesis acquisitions, and application of volume rendering methods to enable rapid, effective review of 3D data are among the key enabling technologies for tomosynthesis. Phantom studies have demonstrated significantly enhanced performance of tomosynthesis compared to standard digital mammography exams. Over 200 patients have been imaged with a prototype system. Typical patient images will be shown.

  5. 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

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

    SciTech Connect

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

    2011-12-15

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

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

    SciTech Connect

    Zhao Bo; Zhao Wei

    2008-05-15

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

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

    PubMed

    Yaffe, Martin J

    2014-07-01

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

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

    SciTech Connect

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

    2014-08-15

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

  10. Digital tomosynthesis: technique.

    PubMed

    Yaffe, Martin J; Mainprize, James G

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    PubMed

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

    2015-10-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    SciTech Connect

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

    2010-11-15

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

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

    SciTech Connect

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

    2006-04-15

    Although conventional mammography is currently the best modality to detect early breast cancer, it is limited in that the recorded image represents the superposition of a three-dimensional (3D) object onto a 2D plane. Recently, two promising approaches for 3D volumetric breast imaging have been proposed, breast tomosynthesis (BT) and CT breast imaging (CTBI). To investigate possible improvements in lesion detection accuracy with either breast tomosynthesis or CT breast imaging as compared to digital mammography (DM), a computer simulation study was conducted using simulated lesions embedded into a structured 3D breast model. The computer simulation realistically modeled x-ray transport through a breast model, as well as the signal and noise propagation through a CsI based flat-panel imager. Polyenergetic x-ray spectra of Mo/Mo 28 kVp for digital mammography, Mo/Rh 28 kVp for BT, and W/Ce 50 kVp for CTBI were modeled. For the CTBI simulation, the intensity of the x-ray spectra for each projection view was determined so as to provide a total average glandular dose of 4 mGy, which is approximately equivalent to that given in conventional two-view screening mammography. The same total dose was modeled for both the DM and BT simulations. Irregular lesions were simulated by using a stochastic growth algorithm providing lesions with an effective diameter of 5 mm. Breast tissue was simulated by generating an ensemble of backgrounds with a power law spectrum, with the composition of 50% fibroglandular and 50% adipose tissue. To evaluate lesion detection accuracy, a receiver operating characteristic (ROC) study was performed with five observers reading an ensemble of images for each case. The average area under the ROC curves (A{sub z}) was 0.76 for DM, 0.93 for BT, and 0.94 for CTBI. Results indicated that for the same dose, a 5 mm lesion embedded in a structured breast phantom was detected by the two volumetric breast imaging systems, BT and CTBI, with statistically

  2. 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.

  3. 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

  4. 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

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

    PubMed

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

    2016-02-01

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

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

    SciTech Connect

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

    2008-09-15

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

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

    PubMed

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

    2011-10-01

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

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

    SciTech Connect

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

    2012-05-15

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

  9. High-speed large angle mammography tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Eberhard, Jeffrey W.; Staudinger, Paul; Smolenski, Joe; Ding, Jason; Schmitz, Andrea; McCoy, Julie; Rumsey, Michael; Al-Khalidy, Abdulrahman; Ross, William; Landberg, Cynthia E.; Claus, Bernhard E. H.; Carson, Paul; Goodsitt, Mitchell; Chan, Heang-Ping; Roubidoux, Marilyn; Thomas, Jerry A.; Osland, Jacqueline

    2006-03-01

    A new mammography tomosynthesis prototype system that acquires 21 projection images over a 60 degree angular range in approximately 8 seconds has been developed and characterized. Fast imaging sequences are facilitated by a high power tube and generator for faster delivery of the x-ray exposure and a high speed detector read-out. An enhanced a-Si/CsI flat panel digital detector provides greater DQE at low exposure, enabling tomo image sequence acquisitions at total patient dose levels between 150% and 200% of the dose of a standard mammographic view. For clinical scenarios where a single MLO tomographic acquisition per breast may replace the standard CC and MLO views, total tomosynthesis breast dose is comparable to or below the dose in standard mammography. The system supports co-registered acquisition of x-ray tomosynthesis and 3-D ultrasound data sets by incorporating an ultrasound transducer scanning system that flips into position above the compression paddle for the ultrasound exam. Initial images acquired with the system are presented.

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

    PubMed

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

    2016-04-01

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

  11. Digital Longitudinal Tomosynthesis

    NASA Astrophysics Data System (ADS)

    Rimkus, Daniel Steven

    1985-12-01

    The purpose of this dissertation was to investigate the clinical utility of digital longitudinal tomosynthesis in radiology. By acquiring a finite group of digital images during a longitudinal tomographic exposure, and processing these images, tomographic planes, other than the fulcrum plane, can be reconstructed. This process is now termed "tomosynthesis". A prototype system utilizing this technique was developed. Both phantom and patient studies were done with this system. The phantom studies were evaluated by subjective, visual criterion and by quantitative analysis of edge sharpness and noise in the reconstructions. Two groups of patients and one volunteer were studied. The first patient group consisted of 8 patients undergoing intravenous urography (IVU). These patients had digital tomography and film tomography of the abdomen. The second patient group consisted of 4 patients with lung cancer admitted to the hospital for laser resection of endobronchial tumor. These patients had mediastinal digital tomograms to evaluate the trachea and mainstem bronchi. The knee of one volunteer was imaged by film tomography and digital tomography. The results of the phantom studies showed that the digital reconstructions accurately produced images of the desired planes. The edge sharpness of the reconstructions approached that of the acquired images. Adequate reconstructions were achieved with as few as 5 images acquired during the exposure, with the quality of the reconstructions improving as the number of images acquired increased. The IVU patients' digital studies had less contrast and spatial resolution than the film tomograms. The single renal lesion visible on the film tomograms was also visible in the digital images. The digital mediastinal studies were felt by several radiologists to be superior to a standard chest xray in evaluating the airways. The digital images of the volunteer's knee showed many of the same anatomic features as the film tomogram, but the digital

  12. Ray-tracing-based reconstruction algorithms for digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Zhou, Weihua; Lu, Jianping; Zhou, Otto; Chen, Ying

    2015-03-01

    As a breast-imaging technique, digital breast tomosynthesis has great potential to improve the diagnosis of early breast cancer over mammography. Ray-tracing-based reconstruction algorithms, such as ray-tracing back projection, maximum-likelihood expectation maximization (MLEM), ordered-subset MLEM (OS-MLEM), and simultaneous algebraic reconstruction technique (SART), have been developed as reconstruction methods for different breast tomosynthesis systems. This paper provides a comparative study to investigate these algorithms by computer simulation and phantom study. Experimental results suggested that, among the four investigated reconstruction algorithms, OS-MLEM and SART performed better in interplane artifact removal with a fast speed convergence.

  13. Scatter radiation in digital tomosynthesis of the breast

    SciTech Connect

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

    2007-02-15

    Digital tomosynthesis of the breast is being investigated as one possible solution to the problem of tissue superposition present in planar mammography. This imaging technique presents various advantages that would make it a feasible replacement for planar mammography, among them similar, if not lower, radiation glandular dose to the breast; implementation on conventional digital mammography technology via relatively simple modifications; and fast acquisition time. One significant problem that tomosynthesis of the breast must overcome, however, is the reduction of x-ray scatter inclusion in the projection images. In tomosynthesis, due to the projection geometry and radiation dose considerations, the use of an antiscatter grid presents several challenges. Therefore, the use of postacquisition software-based scatter reduction algorithms seems well justified, requiring a comprehensive evaluation of x-ray scatter content in the tomosynthesis projections. This study aims to gain insight into the behavior of x-ray scatter in tomosynthesis by characterizing the scatter point spread functions (PSFs) and the scatter to primary ratio (SPR) maps found in tomosynthesis of the breast. This characterization was performed using Monte Carlo simulations, based on the Geant4 toolkit, that simulate the conditions present in a digital tomosynthesis system, including the simulation of the compressed breast in both the cranio-caudal (CC) and the medio-lateral oblique (MLO) views. The variation of the scatter PSF with varying tomosynthesis projection angle, as well as the effects of varying breast glandular fraction and x-ray spectrum, was analyzed. The behavior of the SPR for different projection angle, breast size, thickness, glandular fraction, and x-ray spectrum was also analyzed, and computer fit equations for the magnitude of the SPR at the center of mass for both the CC and the MLO views were found. Within mammographic energies, the x-ray spectrum was found to have no appreciable

  14. Scatter radiation in digital tomosynthesis of the breast

    PubMed Central

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

    2008-01-01

    Digital tomosynthesis of the breast is being investigated as one possible solution to the problem of tissue superposition present in planar mammography. This imaging technique presents various advantages that would make it a feasible replacement for planar mammography, among them similar, if not lower, radiation glandular dose to the breast; implementation on conventional digital mammography technology via relatively simple modifications; and fast acquisition time. One significant problem that tomosynthesis of the breast must overcome, however, is the reduction of x-ray scatter inclusion in the projection images. In tomosynthesis, due to the projection geometry and radiation dose considerations, the use of an antiscatter grid presents several challenges. Therefore, the use of postacquisition software-based scatter reduction algorithms seems well justified, requiring a comprehensive evaluation of x-ray scatter content in the tomosynthesis projections. This study aims to gain insight into the behavior of x-ray scatter in tomosynthesis by characterizing the scatter point spread functions (PSFs) and the scatter to primary ratio (SPR) maps found in tomosynthesis of the breast. This characterization was performed using Monte Carlo simulations, based on the Geant4 toolkit, that simulate the conditions present in a digital tomosynthesis system, including the simulation of the compressed breast in both the cranio-caudal (CC) and the medio-lateral oblique (MLO) views. The variation of the scatter PSF with varying tomosynthesis projection angle, as well as the effects of varying breast glandular fraction and x-ray spectrum, was analyzed. The behavior of the SPR for different projection angle, breast size, thickness, glandular fraction, and x-ray spectrum was also analyzed, and computer fit equations for the magnitude of the SPR at the center of mass for both the CC and the MLO views were found. Within mammographic energies, the x-ray spectrum was found to have no appreciable

  15. Overview of digital breast tomosynthesis: Clinical cases, benefits and disadvantages.

    PubMed

    Nguyen, T; Levy, G; Poncelet, E; Le Thanh, T; Prolongeau, J F; Phalippou, J; Massoni, F; Laurent, N

    2015-09-01

    In France, the national breast cancer-screening program is based on mammography combined with clinical breast examination, and sometimes breast ultrasound for patients with high breast density. Digital breast tomosynthesis is a currently assessed 3D imaging technique in which angular projections of the stationary compressed breast are acquired automatically. When combined with mammography, clinicians can review both conventional (2D) as well as three-dimensional (3D) data. The purpose of this article is to review recent reports on this new breast imaging technique and complements this information with our personal experience. The main advantages of tomosynthesis are that it facilitates the detection and characterization of breast lesions, as well as the diagnosis of occult lesions in dense breasts. However, to do this, patients are exposed to higher levels of radiation than with 2D mammography. In France, the indications for tomosynthesis and its use in breast cancer-screening (individual and organized) are yet to be defined, as is its role in the diagnosis and staging of breast cancer (multiple lesions). Further studies assessing in particular the combined reconstruction of the 2D view using 3D tomosynthesis data acquired during a single breast compression event, and therefore reducing patient exposure to radiation, are expected to provide valuable insight. PMID:26275829

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

    SciTech Connect

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

    2014-06-15

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

  17. Digital breast tomosynthesis with minimal breast compression

    NASA Astrophysics Data System (ADS)

    Scaduto, David A.; Yang, Min; Ripton-Snyder, Jennifer; Fisher, Paul R.; Zhao, Wei

    2015-03-01

    Breast compression is utilized in mammography to improve image quality and reduce radiation dose. Lesion conspicuity is improved by reducing scatter effects on contrast and by reducing the superposition of tissue structures. However, patient discomfort due to breast compression has been cited as a potential cause of noncompliance with recommended screening practices. Further, compression may also occlude blood flow in the breast, complicating imaging with intravenous contrast agents and preventing accurate quantification of contrast enhancement and kinetics. Previous studies have investigated reducing breast compression in planar mammography and digital breast tomosynthesis (DBT), though this typically comes at the expense of degradation in image quality or increase in mean glandular dose (MGD). We propose to optimize the image acquisition technique for reduced compression in DBT without compromising image quality or increasing MGD. A zero-frequency signal-difference-to-noise ratio model is employed to investigate the relationship between tube potential, SDNR and MGD. Phantom and patient images are acquired on a prototype DBT system using the optimized imaging parameters and are assessed for image quality and lesion conspicuity. A preliminary assessment of patient motion during DBT with minimal compression is presented.

  18. Frequently Asked Questions about Digital Mammography

    MedlinePlus

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

  19. Radiation dosimetry in digital breast tomosynthesis: Report of AAPM Tomosynthesis Subcommittee Task Group 223

    SciTech Connect

    Sechopoulos, Ioannis; Sabol, John M.; Berglund, Johan; Bolch, Wesley E.; Brateman, Libby; Christodoulou, Emmanuel; Goodsitt, Mitchell; Flynn, Michael; Geiser, William; Kyle Jones, A.; Lo, Joseph Y.; Paul Segars, W.; Maidment, Andrew D. A.; Nishino, Kazuyoshi; Nosratieh, Anita; and others

    2014-09-15

    The radiation dose involved in any medical imaging modality that uses ionizing radiation needs to be well understood by the medical physics and clinical community. This is especially true of screening modalities. Digital breast tomosynthesis (DBT) has recently been introduced into the clinic and is being used for screening for breast cancer in the general population. Therefore, it is important that the medical physics community have the required information to be able to understand, estimate, and communicate the radiation dose levels involved in breast tomosynthesis imaging. For this purpose, the American Association of Physicists in Medicine Task Group 223 on Dosimetry in Tomosynthesis Imaging has prepared this report that discusses dosimetry in breast imaging in general, and describes a methodology and provides the data necessary to estimate mean breast glandular dose from a tomosynthesis acquisition. In an effort to maximize familiarity with the procedures and data provided in this Report, the methodology to perform the dose estimation in DBT is based as much as possible on that used in mammography dose estimation.

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  1. Computation of the glandular radiation dose in digital tomosynthesis of the breast

    PubMed Central

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

    2008-01-01

    Tomosynthesis of the breast is currently a topic of intense interest as a logical next step in the evolution of digital mammography. This study reports on the computation of glandular radiation dose in digital tomosynthesis of the breast. Previously, glandular dose estimations in tomosynthesis have been performed using data from studies of radiation dose in conventional planar mammography. This study evaluates, using Monte Carlo methods, the normalized glandular dose (DgN) to the breast during a tomosynthesis study, and characterizes its dependence on breast size, tissue composition, and x-ray spectrum. The conditions during digital tomosynthesis imaging of the breast were simulated using a computer program based on the Geant4 toolkit. With the use of simulated breasts of varying size, thickness and tissue composition, the DgN to the breast tissue was computed for varying x-ray spectra and tomosynthesis projection angle. Tomosynthesis projections centered about both the cranio-caudal (CC) and medio-lateral oblique (MLO) views were simulated. For each projection angle, the ratio of the glandular dose for that projection to the glandular dose for the zero degree projection was computed. This ratio was denoted the relative glandular dose (RGD) coefficient, and its variation under different imaging parameters was analyzed. Within mammographic energies, the RGD was found to have a weak dependence on glandular fraction and x-ray spectrum for both views. A substantial dependence on breast size and thickness was found for the MLO view, and to a lesser extent for the CC view. Although RGD values deviate substantially from unity as a function of projection angle, the RGD averaged over all projections in a complete tomosynthesis study varies from 0.91 to 1.01. The RGD results were fit to mathematical functions and the resulting equations are provided. PMID:17278508

  2. Computation of the glandular radiation dose in digital tomosynthesis of the breast

    SciTech Connect

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

    2007-01-15

    Tomosynthesis of the breast is currently a topic of intense interest as a logical next step in the evolution of digital mammography. This study reports on the computation of glandular radiation dose in digital tomosynthesis of the breast. Previously, glandular dose estimations in tomosynthesis have been performed using data from studies of radiation dose in conventional planar mammography. This study evaluates, using Monte Carlo methods, the normalized glandular dose (D{sub g}N) to the breast during a tomosynthesis study, and characterizes its dependence on breast size, tissue composition, and x-ray spectrum. The conditions during digital tomosynthesis imaging of the breast were simulated using a computer program based on the Geant4 toolkit. With the use of simulated breasts of varying size, thickness and tissue composition, the D{sub g}N to the breast tissue was computed for varying x-ray spectra and tomosynthesis projection angle. Tomosynthesis projections centered about both the cranio-caudal (CC) and medio-lateral oblique (MLO) views were simulated. For each projection angle, the ratio of the glandular dose for that projection to the glandular dose for the zero degree projection was computed. This ratio was denoted the relative glandular dose (RGD) coefficient, and its variation under different imaging parameters was analyzed. Within mammographic energies, the RGD was found to have a weak dependence on glandular fraction and x-ray spectrum for both views. A substantial dependence on breast size and thickness was found for the MLO view, and to a lesser extent for the CC view. Although RGD values deviate substantially from unity as a function of projection angle, the RGD averaged over all projections in a complete tomosynthesis study varies from 0.91 to 1.01. The RGD results were fit to mathematical functions and the resulting equations are provided.

  3. Digital breast tomosynthesis and the challenges of implementing an emerging breast cancer screening technology into clinical practice.

    PubMed

    Lee, Christoph I; Lehman, Constance D

    2013-12-01

    Emerging imaging technologies, including digital breast tomosynthesis, have the potential to transform breast cancer screening. However, the rapid adoption of these new technologies outpaces the evidence of their clinical and cost-effectiveness. The authors describe the forces driving the rapid diffusion of tomosynthesis into clinical practice, comparing it with the rapid diffusion of digital mammography shortly after its introduction. They outline the potential positive and negative effects that adoption can have on imaging workflow and describe the practice management challenges when incorporating tomosynthesis. The authors also provide recommendations for collecting evidence supporting the development of policies and best practices. PMID:24295940

  4. Quantification of resolution in multiplanar reconstructions for digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Vent, Trevor L.; Acciavatti, Raymond J.; Kwon, Young Joon; Maidment, Andrew D. A.

    2016-03-01

    Multiplanar reconstruction (MPR) in digital breast tomosynthesis (DBT) allows tomographic images to be portrayed in various orientations. We have conducted research to determine the resolution of tomosynthesis MPR. We built a phantom that houses a star test pattern to measure resolution. This phantom provides three rotational degrees of freedom. The design consists of two hemispheres with longitudinal and latitudinal grooves that reference angular increments. When joined together, the hemispheres form a dome that sits inside a cylindrical encasement. The cylindrical encasement contains reference notches to match the longitudinal and latitudinal grooves that guide the phantom's rotations. With this design, any orientation of the star-pattern can be analyzed. Images of the star-pattern were acquired using a DBT mammography system at the Hospital of the University of Pennsylvania. Images taken were reconstructed and analyzed by two different methods. First, the maximum visible frequency (in line pairs per millimeter) of the star test pattern was measured. Then, the contrast was calculated at a fixed spatial frequency. These analyses confirm that resolution decreases with tilt relative to the breast support. They also confirm that resolution in tomosynthesis MPR is dependent on object orientation. Current results verify that the existence of super-resolution depends on the orientation of the frequency; the direction parallel to x-ray tube motion shows super-resolution. In conclusion, this study demonstrates that the direction of the spatial frequency relative to the motion of the x-ray tube is a determinant of resolution in MPR for DBT.

  5. Clinical performance evaluation of the prototype digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kim, H.; Park, H.; Choi, J.; Choi, Y.

    2012-03-01

    The rapid development and clinical use of digital mammography in the past decade has made possible the development of digital breast tomosynthesis (DBT), which can overcome the limitation of conventional mammography and improve the specificity of mammography with improved marginal visibility of lesion and early breast cancer detection, especially for women with dense breast. The purpose of this study is to characterize the physical properties of DBT system and to optimize the exposure condition using effective modulation transfer function (eMTF), effective noise power spectrum (eNPS), and effective detective quantum efficiency (eDQE). The first generation KERI prototype digital tomosyntesis system for breast imaging using CMOS flat panel detector was used in this study. It was found that the spatial frequency dependent metrics depend on both the inherent properties of the detector and imaging geometry including breast thickness. For thicker breast, eDQE decreases as scatter fraction increases at fixed tube voltage. Moreover, eMTF shows no significant difference as changing tube voltage while eDQE at 27 kVp is relatively degraded. Consequently, the quantitative evaluation of the DBT system with different exposure condition and breast thickness should be fully considered before building the system and application in clinical hospital.

  6. Digital Breast Tomosynthesis: Lessons Learned from Early Clinical Implementation

    PubMed Central

    Maidment, Andrew D. A.; Weinstein, Susan P.; Roth, Susan Orel; Conant, Emily F.

    2014-01-01

    The limitations of mammography are well known and are partly related to the fact that with conventional imaging, the three-dimensional volume of the breast is imaged and presented in a two-dimensional format. Because normal breast tissue is similar in x-ray attenuation to some breast cancers, clinically relevant malignancies may be obscured by normal overlapping tissue. In addition, complex areas of normal tissue may be perceived as suspicious. The limitations of two-dimensional breast imaging lead to low sensitivity in detecting some cancers and high false-positive recall rates. Although mammographic screening has been shown to reduce breast cancer deaths by approximately 30%, controversy exists over when and how often screening mammography should occur. Digital breast tomosynthesis (DBT) is rapidly being implemented in breast imaging clinics around the world as early clinical data demonstrate that it may address some of the limitations of conventional mammography. With DBT, multiple low-dose x-ray images are acquired in an arc and reconstructed to create a three-dimensional image, thus minimizing the impact of overlapping breast tissue and improving lesion conspicuity. Early studies of screening DBT have shown decreased false-positive callback rates and increased rates of cancer detection (particularly for invasive cancers), resulting in increased sensitivity and specificity. In our clinical practice, we have completed more than 2 years of using two-view digital mammography combined with two-view DBT for all screening and select diagnostic imaging examinations (over 25,000 patients). Our experience, combined with previously published data, demonstrates that the combined use of DBT and digital mammography is associated with improved outcomes for screening and diagnostic imaging. Online supplemental material is available for this article. ©RSNA, 2014 PMID:25019451

  7. 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 ...

  8. Uses of megavoltage digital tomosynthesis in radiotherapy

    NASA Astrophysics Data System (ADS)

    Sarkar, Vikren

    With the advent of intensity modulated radiotherapy, radiation treatment plans are becoming more conformal to the tumor with the decreasing margins. It is therefore of prime importance that the patient be positioned correctly prior to treatment. Therefore, image guided treatment is necessary for intensity modulated radiotherapy plans to be implemented successfully. Current advanced imaging devices require costly hardware and software upgrade, and radiation imaging solutions, such as cone beam computed tomography, may introduce extra radiation dose to the patient in order to acquire better quality images. Thus, there is a need to extend current existing imaging device ability and functions while reducing cost and radiation dose. Existing electronic portal imaging devices can be used to generate computed tomography-like tomograms through projection images acquired over a small angle using the technique of cone-beam digital tomosynthesis. Since it uses a fraction of the images required for computed tomography reconstruction, use of this technique correspondingly delivers only a fraction of the imaging dose to the patient. Furthermore, cone-beam digital tomosynthesis can be offered as a software-only solution as long as a portal imaging device is available. In this study, the feasibility of performing digital tomosynthesis using individually-acquired megavoltage images from a charge coupled device-based electronic portal imaging device was investigated. Three digital tomosynthesis reconstruction algorithms, the shift-and-add, filtered back-projection, and simultaneous algebraic reconstruction technique, were compared considering the final image quality and radiation dose during imaging. A software platform, DART, was created using a combination of the Matlab and C++ languages. The platform allows for the registration of a reference Cone Beam Digital Tomosynthesis (CBDT) image against a daily acquired set to determine how to shift the patient prior to treatment. Finally

  9. New method for 3D reconstruction in digital tomosynthesis

    NASA Astrophysics Data System (ADS)

    Claus, Bernhard E. H.; Eberhard, Jeffrey W.

    2002-05-01

    Digital tomosynthesis mammography is an advanced x-ray application that can provide detailed 3D information about the imaged breast. We introduce a novel reconstruction method based on simple backprojection, which yields high contrast reconstructions with reduced artifacts at a relatively low computational complexity. The first step in the proposed reconstruction method is a simple backprojection with an order statistics-based operator (e.g., minimum) used for combining the backprojected images into a reconstructed slice. Accordingly, a given pixel value does generally not contribute to all slices. The percentage of slices where a given pixel value does not contribute, as well as the associated reconstructed values, are collected. Using a form of re-projection consistency constraint, one now updates the projection images, and repeats the order statistics backprojection reconstruction step, but now using the enhanced projection images calculated in the first step. In our digital mammography application, this new approach enhances the contrast of structures in the reconstruction, and allows in particular to recover the loss in signal level due to reduced tissue thickness near the skinline, while keeping artifacts to a minimum. We present results obtained with the algorithm for phantom images.

  10. Clinical benefits of combined diagnostic three-dimensional digital breast tomosynthesis and ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Varjonen, Mari; Pamilo, Martti; Raulisto, Leena

    2005-04-01

    Our goal is to evaluate diagnostic digital breast tomosynthesis and ultrasound imaging clinical value in detecting and diagnosing early stage breast cancers. Determine if fusion imaging would decrease the number of biopsies and reduce further patient workup otherwise required to establish a definitive diagnosis. This paper presents the clinical results based on the study conducted at Helsinki University Central Hospital. Presentation demonstrates clinical dual modality images and results. Tomosynthesis of amorphous selenium based full field digital mammography system will be also presented. Forty asymptomatic women enrolled in the study based on prior identification of suspicious findings on screening mammograms where the possibility of breast cancer could not be excluded. Abnormal screening mammogram findings included tumor-like densities, parenchymal asymmetries and architectural distortions. Eight women were operated and 32 were not referred for surgery. Those cases, which were operated, three lesions represented ductal carcinoma in situ, two ductal carcinomas, one atypical ductal hyperplasia, one fibroadenoma and one radial scar. The 32 not operated cases revealed to be benign or superimposition of normal parenchymal breast tissue. The cases were returned to biennial screening. Ultrasound did not show clearly any lesions, but using tomosynthesis and ultrasound together we were able to analyze and locate the lesions exactly. Special tomosynthesis improves overall lesion detection and analysis. The value of tomosynthesis and ultrasound fusion imaging will be to provide additional clinical information in order to improve decision making accuracy to either confirm or exclude a suspected abnormality and in particular detect small breast cancers.

  11. Power spectrum analysis of the x-ray scatter signal in mammography and breast tomosynthesis projections

    PubMed Central

    Sechopoulos, Ioannis; Bliznakova, Kristina; Fei, Baowei

    2013-01-01

    Purpose: To analyze the frequency domain characteristics of the signal in mammography images and breast tomosynthesis projections with patient tissue texture due to detected scattered x-rays. Methods: Acquisitions of x-ray projection images of 19 different patient breasts were simulated using previously acquired volumetric patient images. Acquisition of these images was performed with a dedicated breast CT prototype system, and the images were classified into voxels representing skin, adipose, and glandular tissue with a previously validated automated algorithm. The classified three dimensional images then underwent simulated mechanical compression representing that which is performed during acquisition of mammography and breast tomosynthesis images. The acquisition of projection images of each patient breast was simulated using Monte Carlo methods with each simulation resulting in two images: one of the primary (non-scattered) signal and one of the scatter signal. To analyze the scatter signal for both mammography and breast tomosynthesis, two projections images of each patient breast were simulated, one with the x-ray source positioned at 0° (mammography and central tomosynthesis projection) and at 30° (wide tomosynthesis projection). The noise power spectra (NPS) for both the scatter signal alone and the total signal (primary + scatter) for all images were obtained and the combined results of all patients analyzed. The total NPS was fit to the expected power-law relationship NPS(f) = k/f^β and the results were compared with those previously published on the power spectrum characteristics of mammographic texture. The scatter signal alone was analyzed qualitatively and a power-law fit was also performed. Results: The mammography and tomosynthesis projections of three patient breasts were too small to analyze, so a total of 16 patient breasts were analyzed. The values of β for the total signal of the 0° projections agreed well with previously published results

  12. Physical performance testing of digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Kuwabara, Takao; Yoshikawa, Kenji

    2015-03-01

    Digital breast tomosynthesis has become accepted in clinical use. It is important to physically evaluate a system to ensure that it is working at full performance. Non-linear reconstruction processing is proposed to improve interpretation of clinical images by enhancing the minute contrasts of breast tissue while suppressing metal artifacts. Because existing measuring methods assume a linear system, physical evaluation applied to images reconstructed with non-linear processing may result in unnatural values. We investigated the influence of different reconstruction methods on physical evaluations. We suggest using images reconstructed by back projection processing without a filter to ensure the device performance directly.

  13. Digital mammography: current state and future aspects.

    PubMed

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

    2006-01-01

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

  14. A stationary digital breast tomosynthesis system: Design simulation, characterization and image reconstruction

    NASA Astrophysics Data System (ADS)

    Rajaram, Ramya

    Conventional screen-film and/or digital mammography, despite being the most popular breast imaging modalities, suffer from certain limitations, most important of which is tissue overlap and false diagnoses arising thereof. A new three-dimensional alternative for breast cancer screening and diagnosis is tomosynthesis in which a limited number of low-dose two-dimensional projection images of a patient are used to reconstruct the three-dimensional tissue information. The tomosynthesis systems currently under development all incorporate an x-ray source that moves over a certain angle to acquire images. This tube motion is a major limitation because it degrades image quality, increases the scan time and causes prolonged patient discomfort. The availability of independently controllable carbon nanotube cathodes enabled us to explore the possibility of setting up a stationary multi-beam imaging system. In this dissertation we have proposed a stationary digital breast tomosynthesis scanner using spatially distributed carbon nanotube based field emission x-ray sources. We have presented details about the design, set-up, characterization and image reconstruction of the completely stationary digital breast tomosynthesis system. This system has the potential to reduce the total scan time and improve the image quality in breast imaging. Extensive design simulation results have been used to decide on the final system set-up. The fully assembled actual experimental system is capable of acquiring all the images in as little as eight seconds and yield superior image quality as well. The system has been completely characterized in terms of focal spot size, system resolution and geometric calibration. Certain important results have been obtained during the process that we hope will set the standard for the characterization of the future systems. A novel iterative reconstruction algorithm has been tried on the projection images obtained from the tomosynthesis system. Our algorithm has

  15. Efficacy of digital breast tomosynthesis for breast cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Alakhras, M.; Mello-Thoms, C.; Rickard, M.; Bourne, R.; Brennan, P. C.

    2014-03-01

    Purpose: To compare the diagnostic performance of digital breast tomosynthesis (DBT) in combination with digital mammography (DM) with that of digital mammography alone. Materials and Methods: Twenty six experienced radiologists who specialized in breast imaging read 50 cases (27 cancers and 23 non-cancer cases) of patients who underwent DM and DBT. Both exams included the craniocaudal (CC) and mediolateral oblique (MLO) views. Histopathologic examination established truth in all lesions. Each case was interpreted in two modes, once with DM alone followed by DM+DBT, and the observers were asked to mark the location of any lesions, if present, and give it a score based on a five-category assessment by the Royal Australian and New Zealand College of Radiologists (RANZCR). The diagnostic performance of DM compared with that of DM+DBT was evaluated in terms of the difference between areas under receiver-operating characteristic curves (AUCs), Jackknife free-response receiver operator characteristics (JAFROC) figure-of-merit, sensitivity, location sensitivity and specificity. Results: Average AUC and JAFROC for DM versus DM+DBT was significantly different (AUCs 0.690 vs 0.781, p=< 0.0001), (JAFROC 0.618 vs. 0.732, p=< 0.0001) respectively. In addition, the use of DM+DBT resulted in an improvement in sensitivity (0.629 vs. 0.701, p=0.0011), location sensitivity (0.548 vs. 0.690, p=< 0.0001) and specificity (0.656 vs. 0.758, p=0.0015) when compared to DM alone. Conclusion: Adding DBT to the standard DM significantly improved radiologists' performance in terms of AUCs, JAFROC figure of merit, sensitivity, location sensitivity and specificity values.

  16. Task-based assessment and optimization of digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Young, Stefano

    Digital breast tomosynthesis (DBT) is a new technology for breast cancer screening that promises to complement mammography or supersede it to become the standard for breast imaging. DBT involves taking multiple images in order to synthesize a new image that represents a slice through the breast volume---hence the term tomosynthesis. The primary advantage of this paradigm is that it can reduce the amount of overlapping anatomy in the data, leading to improved visualization of potentially-cancerous findings. The difficulty in DBT is quantifying the advantages of the technology and determining the optimal conditions for its clinical use. This dissertation describes a virtual trial framework for assessing and optimizing DBT technology for the specific task of detecting small, low-contrast masses in the breast. It addresses each component of the imaging chain to some degree, from the patients/phantoms to the imaging hardware to the model observers used to measure signal detectability. The main focus, however, is on quantifying tradeoffs between three key parameters that affect image quality: (1) scan angle, (2) number of projections, and (3) exposure. We show that in low-density breast phantoms, detectability generally increases with both scan angle and number of projections in the anatomical-variability-limited (high-exposure) regime. We also investigate how breast density affects the optimal DBT scan parameters. We show task-specific results that support using an adaptive paradigm in DBT, where the imaging system reconfigures itself in response to information about the patient's breast density. The virtual framework described in this dissertation provides a platform for further investigations of image quality in 3D breast imaging.

  17. Initial clinical evaluation of stationary digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Calliste, Jabari; Tucker, Andrew W.; Gidcumb, Emily; Kuzmiak, Cherie M.; Lu, Jianping; Zhou, Otto; Lee, Yueh Z.

    2015-03-01

    Full field digital mammography (FFDM) has been the gold standard for mammography. It detects the presence, distribution, and morphology of microcalcifications (MCs), helping predict malignancy. Digital breast tomosynthesis (DBT) has overcome some limitations of FFDM such as poor sensitivity, specificity, and positive predictive values, due to superimposition of tissue, especially in dense breasts. Current DBT systems move an x-ray tube in either continuous (CM), or step-and-shoot motion (SSM). These systems are less effective than FFDM in MC detection due to lower spatial resolution. Motion of the x-ray source and system mechanical instability cause image blur. The image quality is further affected by patient motion due to the relatively long scan time. We developed a stationary DBT (s-DBT) system using a carbon nanotube (CNT) X-ray source array. The CNT array is electronically controlled, rapidly acquiring projection images over a large angular span, with zero tube motion. No source motion, coupled with a large angular span, results in improved in-plane and depth resolution. Using physical phantoms and human specimens, this system demonstrated higher spatial resolution than CM DBT. The objective of this study is to compare the diagnostic clinical performance of s-DBT to that of FFDM. Under UNC's IRB regulations, 100 patients with breast lesions are being recruited and imaged with both modalities. A reader study will compare the diagnostic accuracy of the modalities. We have successfully imaged the first 30 patients. Initial results indicate that s-DBT alone produces comparable MC sharpness, and increased lesion conspicuity compared to FFDM.

  18. Design and feasibility studies of a stationary digital breast tomosynthesis system.

    PubMed

    Yang, G; Qian, X; Phan, T; Sprenger, F; Sultana, S; Calderon-Colon, X; Kearse, B; Spronk, D; Lu, J; Zhou, O

    2011-08-21

    Studies have shown that digital breast tomosynthesis (DBT) can improve breast cancer diagnosis by reconstructing 3D images. However, DBT scanners based on rotation gantry prolong the imaging time and reduce spatial resolution due to motion comparing with the regular two-view mammography. To obtain three dimension reconstruction images and maintain the high image quality of conventional mammography, we proposed a prototype stationary digital breast tomosynthesis system (s-DBT). The proposed s-DBT system acquires projection images without mechanical movement. The core component of the s-DBT system is a specially designed spatially distributed multi-beam x-ray tube based on the carbon nanotube field emission x-ray technology. The multi-beam x-ray source array enables collection of all projection images from different viewing angles without mechanical motion. Preliminary results show the s-DBT system can achieve a scan time comparable to the regular two-view mammography, and improve the spatial resolution comparing with rotating gantry DBT. PMID:21808428

  19. Whole-Body Clinical Applications of Digital Tomosynthesis.

    PubMed

    Machida, Haruhiko; Yuhara, Toshiyuki; Tamura, Mieko; Ishikawa, Takuya; Tate, Etsuko; Ueno, Eiko; Nye, Katelyn; Sabol, John M

    2016-01-01

    With flat-panel detector mammography, radiography, and fluoroscopy systems, digital tomosynthesis (DT) has been recently introduced as an advanced clinical application that removes overlying structures, enhances local tissue separation, and provides depth information about structures of interest by providing high-quality tomographic images. DT images are generated from projection image data, typically using filtered back-projection or iterative reconstruction. These low-dose x-ray projection images are easily and swiftly acquired over a range of angles during a single linear or arc sweep of the x-ray tube assembly. DT is advantageous in a variety of clinical contexts, including breast, chest, head and neck, orthopedic, emergency, and abdominal imaging. Specifically, compared with conventional mammography, radiography, and fluoroscopy, as a result of reduced tissue overlap DT can improve detection of breast cancer, pulmonary nodules, sinonasal mucosal thickening, and bone fractures and delineation of complex anatomic structures such as the ostiomeatal unit, atlantoaxial joint, carpal and tarsal bones, and pancreatobiliary and gastrointestinal tracts. Compared with computed tomography, DT offers reduced radiation exposure, better in-plane resolution to improve assessment of fine bony changes, and less metallic artifact, improving postoperative evaluation of patients with metallic prostheses and osteosynthesis materials. With more flexible patient positioning, DT is also useful for functional, weight-bearing, and stress tests. To optimize patient management, a comprehensive understanding of the clinical applications and limitations of whole-body DT applications is important for improvement of diagnostic quality, workflow, and cost-effectiveness. Online supplemental material is available for this article. (©)RSNA, 2016. PMID:27163590

  20. Estimation of scattered radiation in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Diaz, O.; Dance, D. R.; Young, K. C.; Elangovan, P.; Bakic, P. R.; Wells, K.

    2014-08-01

    Digital breast tomosynthesis (DBT) is a promising technique to overcome the tissue superposition limitations found in planar 2D x-ray mammography. However, as most DBT systems do not employ an anti-scatter grid, the levels of scattered radiation recorded within the image receptor are significantly higher than that observed in planar 2D x-ray mammography. Knowledge of this field is necessary as part of any correction scheme and for computer modelling and optimisation of this examination. Monte Carlo (MC) simulations are often used for this purpose, however they are computationally expensive and a more rapid method of calculation is desirable. This issue is addressed in this work by the development of a fast kernel-based methodology for scatter field estimation using a detailed realistic DBT geometry. Thickness-dependent scatter kernels, which were validated against the literature with a maximum discrepancy of 4% for an idealised geometry, have been calculated and a new physical parameter (air gap distance) was used to estimate more accurately the distribution of scattered radiation for a series of anthropomorphic breast phantom models. The proposed methodology considers, for the first time, the effects of scattered radiation from the compression paddle and breast support plate, which can represent more than 30% of the total scattered radiation recorded within the image receptor. The results show that the scatter field estimator can calculate scattered radiation images in an average of 80 min for projection angles up to 25° with equal to or less than a 10% error across most of the breast area when compared with direct MC simulations.

  1. Angular dependence of mammographic dosimeters in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Bradley, Lena R.; Carton, Ann-Katherine; Maidment, Andrew D. A.

    2010-04-01

    Digital Breast Tomosynthesis (DBT) is an emerging imaging modality that combines tomography with conventional digital mammography. In developing DBT dosimetry, a direct application of mammographic dosimetry has appeal. However, DBT introduces rotation of the x-ray tube relative to the dosimeter, thus raising questions about the angular dependence of mammographic dosimeters. To measure this dependence, two ionization chambers, two solid-stated detectors, and one photodiode were rotated relative to an incident Mo/Mo x-ray beam. In this isocentric DBT simulation, the signal of each dosimeter was studied over an angular range of 180° for tube voltages of 26 to 34 kV. One ionization chamber was then modeled numerically to study the response to various monoenergetic beams. The results show that all dosimeters underestimate dose to varying degrees; solid-state detectors show the greatest angular dependence while ionization chambers show the least. Correction factors were computed from the data for isocentric DBT images using projection angles up to +/-25° these factors ranged from 1.0014 to 1.1380. The magnitude of the angular dependence generally decreased with increasing energy, as shown with both the measured and modeled data. As a result, the error arising in measuring DBT dose with a mammographic dosimeter varies significantly; it cannot always be disregarded. The use of correction factors may be possible but is largely impractical, as they are specific to the dosimeter, x-ray beam, and DBT geometry. Instead, an angle-independent dosimeter may be more suitable for DBT.

  2. Low dose scatter correction for digital chest tomosynthesis

    NASA Astrophysics Data System (ADS)

    Inscoe, Christina R.; Wu, Gongting; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

    2015-03-01

    Digital chest tomosynthesis (DCT) provides superior image quality and depth information for thoracic imaging at relatively low dose, though the presence of strong photon scatter degrades the image quality. In most chest radiography, anti-scatter grids are used. However, the grid also blocks a large fraction of the primary beam photons requiring a significantly higher imaging dose for patients. Previously, we have proposed an efficient low dose scatter correction technique using a primary beam sampling apparatus. We implemented the technique in stationary digital breast tomosynthesis, and found the method to be efficient in correcting patient-specific scatter with only 3% increase in dose. In this paper we reported the feasibility study of applying the same technique to chest tomosynthesis. This investigation was performed utilizing phantom and cadaver subjects. The method involves an initial tomosynthesis scan of the object. A lead plate with an array of holes, or primary sampling apparatus (PSA), was placed above the object. A second tomosynthesis scan was performed to measure the primary (scatter-free) transmission. This PSA data was used with the full-field projections to compute the scatter, which was then interpolated to full-field scatter maps unique to each projection angle. Full-field projection images were scatter corrected prior to reconstruction. Projections and reconstruction slices were evaluated and the correction method was found to be effective at improving image quality and practical for clinical implementation.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  4. Increased microcalcification visibility in lumpectomy specimens using a stationary digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Tucker, Andrew W.; Lee, Yueh Z.; Kuzmiak, Cherie M.; Calliste, Jabari; Lu, Jianping; Zhou, Otto

    2014-03-01

    Current digital breast tomosynthesis (DBT) systems have been shown to have diminished microcalcification (MC) visibility compared to 2D mammography systems. Rotating gantry DBT systems require mechanical motion of the X-ray source which causes motion blurring of the focal spot, thus reducing spatial resolution. We have developed a stationary DBT (s-DBT) technology that uses a carbon nanotube (CNT) based X-ray source array in order to acquire all the projections images without any mechanical motion. It is capable of producing full tomosynthesis datasets with zero motion blur. It has been shown to have significantly higher spatial resolution than continuous motion DBT systems. An s-DBT system also allows for a wider angular span without increasing the acquisition time. A larger angular span covers a larger portion of the Fourier domain, thus decreasing the tissue overlap. In this study, we compare tomosynthesis imaging of MCs, in lumpectomy specimens, between an s-DBT system and a rotating gantry DBT system. Results show that s-DBT produces better MC sharpness and reduced tissue overlap compared to continuous motion DBT systems.

  5. Development of a stationary digital breast tomosynthesis system for clinical applications

    NASA Astrophysics Data System (ADS)

    Tucker, Andrew Wallace

    Digital breast tomosynthesis (DBT) has been shown to be a very beneficial tool in the fight against breast cancer. However, current DBT systems have poor spatial resolution compared to full field digital mammography (FFDM), the current gold standard for screening mammography. The poor spatial resolution of DBT systems is a result of the single X-ray source design. In DBT systems a single X-ray source is rotated over an angular span in order to acquire the images needed for 3D reconstruction. The rotation of the X-ray source degrades the spatial resolution of the images. DBT systems which are approved for use in the United States for screening mammography are required to also take a full field digital mammogram with every DBT acquisition in order to compensate for the poor spatial resolution. This double exposure essentially doubles the radiation dose to patients. Over the past few years our research group has developed a carbon nanotube (CNT) based X-ray source technology. The unique nature of CNT X-ray sources allows for multiple X-ray focal spots in a single X-ray source. Using this technology we have recently developed a stationary DBT system (s-DBT) system which is capable of producing a full tomosynthesis image dataset with zero motion of the X-ray source. This system has been shown to have increased spatial resolution over other DBT systems in a laboratory setting. The goal of this thesis work was to optimize the s-DBT system, demonstrate its usefulness over other systems, and finally implement it into the clinic for a clinical trial. The s-DBT system was optimized using different image quality measurements. The optimized system was then used in a breast specimen imaging trial which compared s-DBT to magnified 2D mammography and a conventional single source DBT system. Readers preferred s-DBT to magnified 2D mammography for specimen margin delineation and mass detection, these results were not significant. Using physical measures for spatial resolution the s

  6. Optical geometry calibration method for free-form digital tomosynthesis

    NASA Astrophysics Data System (ADS)

    Chtcheprov, Pavel; Hartman, Allison; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

    2016-03-01

    Digital tomosynthesis is a type of limited angle tomography that allows 3D information to be reconstructed from a set of x-ray projection images taken at various angles using an x-ray tube, a mechanical arm to rotate the tube about the object, and a digital detector. Tomosynthesis reconstruction requires the precise location of the detector with respect to each x-ray source, forcing all current clinical tomosynthesis systems to use a physically coupled source and detector so the geometry is always known and is always the same. This limits the imaging geometries and its large size is impractical for mobile or field operations. To counter this, we have developed a free form tomosynthesis with a decoupled, free-moving source and detector that uses a novel optical method for accurate and real-time geometry calibration to allow for manual, hand-held tomosynthesis and even CT imaging. We accomplish this by using a camera, attached to the source, to track the motion of the source relative to the detector. Attached to the detector is an optical pattern and the image captured by the camera is then used to determine the relative camera/pattern position and orientation by analyzing the pattern distortion and calculating the source positions for each projection, necessary for 3D reconstruction. This allows for portable imaging in the field and also as an inexpensive upgrade to existing 2D systems, such as in developing countries, to provide 3D image data. Here we report the first feasibility demonstrations of free form digital tomosynthesis systems using the method.

  7. Digital tomosynthesis: technique modifications and clinical applications for neurovascular anatomy

    SciTech Connect

    Maravilla, K.R.; Murry, R.C. Jr.; Diehl, J.; Suss, R.; Allen, L.; Chang, K.; Crawford, J.; McCoy, R.

    1984-09-01

    Digital tomosynthesis studies (DTS) using a linear tomographic motion can provide good quality clinical images when combined with subtraction angiotomography. By modifying their hardware system and the computer software algorithms, the authors were able to reconstruct tomosynthesis images using an isocentric rotation (IR) motion. Applying a combination of linear tomographic and IR techniques in clinical cases, they performed DTS studies in six patients, five with aneurysms and one with a hypervascular tumor. The results showed detailed definitions of the pathologic entities and the regional neurovascular anatomy. Based on this early experience, DTS would seem to be a useful technique for the preoperative surgical planning of vascular abnormalities.

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

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

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

  9. Characterization of Breast Lesions: Comparison of Digital Breast Tomosynthesis and Ultrasonography

    PubMed Central

    Kim, Sun Ah; Cho, Nariya; Yi, Ann; Moon, Woo Kyung

    2015-01-01

    Objective To compare the diagnostic performance of digital breast tomosynthesis (DBT) and conventional breast ultrasound (US) to characterize breast lesions as benign or malignant. Materials and Methods A total of 332 women, presenting for screening examinations or for breast biopsy between March and June 2012 were recruited to undergo digital mammography (DM), DBT, and breast US examination. Among them, 113 patients with 119 breast lesions depicted on DM were finally included. Three blinded radiologists performed an enriched reader study and reviewed the DBT and US images. Each reader analyzed the lesions in random order, assigned Breast Imaging Reporting and Data System (BI-RADS) descriptors, rated the images for the likelihood of malignancy (%) and made a BI-RADS final assessment. Diagnostic accuracy, as assessed by the area under the receiver operating characteristic curve, sensitivity, and specificity of DBT and US were compared. Results Among the 119 breast lesions depicted on DM, 75 were malignant and the remaining 44 were benign. The average diagnostic performance for characterizing breast lesions as benign or malignant in terms of area under the curve was 0.899 for DBT and 0.914 for US (p = 0.394). Mean sensitivity (97.3% vs. 98.7%, p = 0.508) and specificity (44.7% vs. 39.4%, p = 0.360) were also not significantly different. Conclusion Digital breast tomosynthesis may provide similar reader lesion characterization performance to that of US for breast lesions depicted on DM. PMID:25741187

  10. System of digital tomosynthesis for nondestructive testing

    SciTech Connect

    Baranov, V.A.; Chekalin, A.S.

    1988-01-01

    The article describes a computerized system of tomographic reconstruction of a three-dimensional object from its two-dimensional projections on the basis of the methods of tomosynthesis. It deals with modified algorithms, the structure of program provisions and instrumental realization of the system. Variants of tomographic reconstruction with filtering are suggested. The results of an experiment with tomographic reconstruction of a test object are presented.

  11. Stationary digital chest tomosynthesis for coronary artery calcium scoring

    NASA Astrophysics Data System (ADS)

    Wu, Gongting; Wang, Jiong; Potuzko, Marci; Harman, Allison; Pearce, Caleb; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

    2016-03-01

    The coronary artery calcium score (CACS) measures the buildup of calcium on the coronary artery wall and has been shown to be an important predictor of the risk of coronary artery diseases (CAD). Currently CACS is measured using CT, though the relatively high cost and high radiation dose has limited its adoption as a routine screening procedure. Digital Chest Tomosynthesis (DCT), a low dose and low cost alternative to CT, and has been shown to achieve 90% of sensitivity of CT in lung disease screening. However commercial DCT requires long scanning time and cannot be adapted for high resolution gated cardiac imaging, necessary for CACS. The stationary DCT system (s- DCT), developed in our lab, has the potential to significantly shorten the scanning time and enables high resolution cardiac gated imaging. Here we report the preliminary results of using s-DCT to estimate the CACS. A phantom heart model was developed and scanned by the s-DCT system and a clinical CT in a phantom model with realistic coronary calcifications. The adapted fan-beam volume reconstruction (AFVR) method, developed specifically for stationary tomosynthesis systems, is used to obtain high resolution tomosynthesis images. A trained cardiologist segmented out the calcifications and the CACS was obtained. We observed a strong correlation between the tomosynthesis derived CACS and CT CACS (r2 = 0.88). Our results shows s-DCT imaging has the potential to estimate CACS, thus providing a possible low cost and low dose imaging protocol for screening and monitoring CAD.

  12. Thickness-dependent scatter correction algorithm for digital mammography

    NASA Astrophysics Data System (ADS)

    Gonzalez Trotter, Dinko E.; Tkaczyk, J. Eric; Kaufhold, John; Claus, Bernhard E. H.; Eberhard, Jeffrey W.

    2002-05-01

    We have implemented a scatter-correction algorithm (SCA) for digital mammography based on an iterative restoration filter. The scatter contribution to the image is modeled by an additive component that is proportional to the filtered unattenuated x-ray photon signal and dependent on the characteristics of the imaged object. The SCA's result is closer to the scatter-free signal than when a scatter grid is used. Presently, the SCA shows improved contrast-to-noise performance relative to the scatter grid for a breast thickness up to 3.6 cm, with potential for better performance up to 6 cm. We investigated the efficacy of our scatter-correction method on a series of x-ray images of anthropomorphic breast phantoms with maximum thicknesses ranging from 3.0 cm to 6.0 cm. A comparison of the scatter-corrected images with the scatter-free signal acquired using a slit collimator shows average deviations of 3 percent or less, even in the edge region of the phantoms. These results indicate that the SCA is superior to a scatter grid for 2D quantitative mammography applications, and may enable 3D quantitative applications in X-ray tomosynthesis.

  13. Semi-automated segmentation and classification of digital breast tomosynthesis reconstructed images.

    PubMed

    Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew; Michaelsen, Kelly E; Krishnaswamy, Venkataramanan; Pogue, Brian W; Paulsen, Keith D

    2011-01-01

    Digital breast tomosynthesis (DBT) is a limited-angle tomographic x-ray imaging technique that reduces the effect of tissue superposition observed in planar mammography. An integrated imaging platform that combines DBT with near infrared spectroscopy (NIRS) to provide co-registered anatomical and functional imaging is under development. Incorporation of anatomic priors can benefit NIRS reconstruction. In this work, we provide a segmentation and classification method to extract potential lesions, as well as adipose, fibroglandular, muscle and skin tissue in reconstructed DBT images that serve as anatomic priors during NIRS reconstruction. The method may also be adaptable for estimating tumor volume, breast glandular content, and for extracting lesion features for potential application to computer aided detection and diagnosis. PMID:22255752

  14. Dose assessment of digital tomosynthesis in pediatric imaging

    NASA Astrophysics Data System (ADS)

    Gislason, Amber; Elbakri, Idris A.; Reed, Martin

    2009-02-01

    We investigated the potential for digital tomosynthesis (DT) to reduce pediatric x-ray dose while maintaining image quality. We utilized the DT feature (VolumeRadTM) on the GE DefiniumTM 8000 flat panel system installed in the Winnipeg Children's Hospital. Facial bones, cervical spine, thoracic spine, and knee of children aged 5, 10, and 15 years were represented by acrylic phantoms for DT dose measurements. Effective dose was estimated for DT and for corresponding digital radiography (DR) and computed tomography (CT) patient image sets. Anthropomorphic phantoms of selected body parts were imaged by DR, DT, and CT. Pediatric radiologists rated visualization of selected anatomic features in these images. Dose and image quality comparisons between DR, DT, and CT determined the usefulness of tomosynthesis for pediatric imaging. CT effective dose was highest; total DR effective dose was not always lowest - depending how many projections were in the DR image set. For the cervical spine, DT dose was close to and occasionally lower than DR dose. Expert radiologists rated visibility of the central facial complex in a skull phantom as better than DR and comparable to CT. Digital tomosynthesis has a significantly lower dose than CT. This study has demonstrated DT shows promise to replace CT for some facial bones and spinal diagnoses. Other clinical applications will be evaluated in the future.

  15. Workload and transmission data for the installation of a digital breast tomosynthesis system

    SciTech Connect

    Li Xinhua; Zhang Da; Liu, Bob

    2013-06-15

    Purpose: Digital breast tomosynthesis (DBT) differs from conventional mammography in target/filter, kVp range, and imaging geometry. The aim of this study was to assess the breast input exposure of a DBT system by completing a workload survey of DBT installations, and to determine the parameters {alpha}, {beta}, and {gamma} in the Archer equation for the primary radiation generated by the clinical workload distributions. Methods: The authors conducted a retrospective survey of the x-ray breast imaging performed between September 2011 and September 2012 in three clinical DBT rooms equipped with Selenia Dimensions systems (Hologic Inc., Bedford, MA). A total of 343 examinations were analyzed to calculate the workload (mA-minute) and the primary air kerma at 1 m from the source (K{sup 1}). Transmission curves were calculated for the primary radiation generated by the workload distributions of the DBT rooms, and were fitted to the Archer equation. Results: There were large variations in patient volume and workload in the three examination rooms. In all these rooms, the average tube voltage (kVp) was about 31, the average K{sup 1} per patient was 16-21 mGy, and the average mA-minute per patient was 1.4-2.2 times higher than that of the mammography room described in NCRP Report No. 147. Most DBT screening examinations consisted of four two-dimensional mammographic views plus four tomosynthesis scans; the numbers of views acquired in diagnostic examinations varied widely. Tomosynthesis scans contributed about 30% of total mA-minute and about 50% of K{sup 1}. For the primary radiation generated by the clinical workload distributions, {alpha} was similar to that of 40-45 kVp W/Al (target/filter), and {alpha}+{beta} was similar to that of 30 kVp W/Al. Conclusions: The workload (mA-minute and K{sup 1}) distributions of mammographic examinations with DBT differ from conventional mammography. A field survey of patient volume and x-ray tube usage is important for the shielding

  16. Authenticity and integrity of digital mammography images.

    PubMed

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

    2001-08-01

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

  17. Development Of A Digital Mammography System

    NASA Astrophysics Data System (ADS)

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

    1988-06-01

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

  18. 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.

  19. A comparison of reconstruction algorithms for C-arm mammography tomosynthesis

    SciTech Connect

    Rakowski, Joseph T.; Dennis, Michael J.

    2006-08-15

    Digital tomosynthesis is an imaging technique to produce a tomographic image from a series of angular digital images in a manner similar to conventional focal plane tomography. Unlike film focal plane tomography, the acquisition of the data in a C-arm geometry causes the image receptor to be positioned at various angles to the reconstruction tomogram. The digital nature of the data allows for input images to be combined into the desired plane with the flexibility of generating tomograms of many separate planes from a single set of input data. Angular datasets were obtained of a low contrast detectability (LCD) phantom and cadaver breast utilizing a Lorad stereotactic biopsy unit with a coupled source and digital detector in a C-arm configuration. Datasets of 9 and 41 low-dose projections were collected over a 30 deg. angular range. Tomographic images were reconstructed using a Backprojection (BP) algorithm, an Iterative Subtraction (IS) algorithm that allows the partial subtraction of out-of-focus planes, and an Algebraic Reconstruction (AR) algorithm. These were compared with single view digital radiographs. The methods' effectiveness at enhancing visibility of an obscured LCD phantom was quantified in terms of the Signal to Noise Ratio (SNR), and Signal to Background Ratio (SBR), all normalized to the metric value for the single projection image. The methods' effectiveness at removing ghosting artifacts in a cadaver breast was quantified in terms of the Artifact Spread Function (ASF). The technology proved effective at partially removing out of focus structures and enhancing SNR and SBR. The normalized SNR was highest at 4.85 for the obscured LCD phantom, using nine projections and IS algorithm. The normalized SBR was highest at 23.2 for the obscured LCD phantom, using 41 projections and an AR algorithm. The highest normalized metric values occurred with the obscured phantom. This supports the assertion that the greatest value of tomosynthesis is in imaging

  20. Digital Mammography: Improvements in Breast Cancer Diagnostic

    SciTech Connect

    Montano Zetina, Luis Manuel

    2006-01-06

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

  1. Characteristics of megavoltage cone-beam digital tomosynthesis

    SciTech Connect

    Descovich, M.; Morin, O.; Aubry, J. F.; Aubin, M.; Chen, J.; Bani-Hashemi, A; Pouliot, J.

    2008-04-15

    This article reports on the image characteristics of megavoltage cone-beam digital tomosynthesis (MVCB DT). MVCB DT is an in-room imaging technique, which enables the reconstruction of several two-dimensional slices from a set of projection images acquired over an arc of 20 deg. - 40 deg. The limited angular range reduces the acquisition time and the dose delivered to the patient, but affects the image quality of the reconstructed tomograms. Image characteristics (slice thickness, shape distortion, and contrast-to-noise ratio) are studied as a function of the angular range. Potential clinical applications include patient setup and the development of breath holding techniques for gated imaging.

  2. Digital tomosynthesis with an on-board kilovoltage imaging device

    SciTech Connect

    Godfrey, Devon J. . E-mail: devon.godfrey@duke.edu; Yin, F.-F.; Oldham, Mark; Yoo, Sua; Willett, Christopher

    2006-05-01

    Purpose: To generate on-board digital tomosynthesis (DTS) and reference DTS images for three-dimensional image-guided radiation therapy (IGRT) as an alternative to conventional portal imaging or on-board cone-beam computed tomography (CBCT). Methods and Materials: Three clinical cases (prostate, head-and-neck, and liver) were selected to illustrate the capabilities of on-board DTS for IGRT. Corresponding reference DTS images were reconstructed from digitally reconstructed radiographs computed from planning CT image sets. The effect of scan angle on DTS slice thickness was examined by computing the mutual information between coincident CBCT and DTS images, as the DTS scan angle was varied from 0{sup o} to 165{sup o}. A breath-hold DTS acquisition strategy was implemented to remove respiratory motion artifacts. Results: Digital tomosynthesis slices appeared similar to coincident CBCT planes and yielded substantially more anatomic information than either kilovoltage or megavoltage radiographs. Breath-hold DTS acquisition improved soft-tissue visibility by suppressing respiratory motion. Conclusions: Improved bony and soft-tissue visibility in DTS images is likely to improve target localization compared with radiographic verification techniques and might allow for daily localization of a soft-tissue target. Breath-hold DTS is a potential alternative to on-board CBCT for sites prone to respiratory motion.

  3. Overview of the evidence on digital breast tomosynthesis in breast cancer detection.

    PubMed

    Houssami, Nehmat; Skaane, Per

    2013-04-01

    Digital breast tomosynthesis (DBT, or 3D-mammography), a three-dimensional derivative of digital mammography (DM), reduces the effect of tissue superimposition and may improve mammographic interpretation. In this review, we examined the evidence on the accuracy of DBT in clinical studies. Published studies of DBT were relatively small studies, mostly test-set observer (reader) studies or clinical series that included symptomatic and screen-recalled cases, and were generally enriched with cancers. With these limitations in mind, the evidence showed some consistent findings, summarized as follows: two-view DBT has at least equal or better accuracy than standard two-view DM, whereas one-view DBT does not have better accuracy than standard DM; the addition of DBT to standard mammography (for mammographic interpretation or for assessment or triage of screen-recalled abnormalities) increases accuracy; improved accuracy from using DBT (relative to, or added to, DM) may be due to increased cancer detection or due to reduced false positive recalls, or both; and subjective interpretation of cancer conspicuity consistently found that cancers were equally or more conspicuous on DBT relative to DM. Preliminary data from population screening trials suggest that the integration of DBT with conventional DM (screen-reading using combined 2D + 3D mammography) may substantially improve breast cancer detection, although final results are not yet available, and many logistical issues need further evaluation to determine the potential implications and cost of combined 2D + 3D mammographic screening. At present, there is insufficient evidence to justify a change from standard DM to DBT however the available data strongly support investment in new large-scale population screening trials. These trials need to avoid the 'double' acquisitions required for 2D + 3D mammograms, and should therefore focus on evaluating integrated 2Dsynthetic + 3D mammography (where 2D-images are

  4. Initial clinical evaluation of stationary digital chest tomosynthesis

    NASA Astrophysics Data System (ADS)

    Hartman, Allison E.; Shan, Jing; Wu, Gongting; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping; Heath, Michael; Wang, Xiaohui; Foos, David

    2016-03-01

    Computed Tomography (CT) is the gold standard for image evaluation of lung disease, including lung cancer and cystic fibrosis. It provides detailed information of the lung anatomy and lesions, but at a relatively high cost and high dose of radiation. Chest radiography is a low dose imaging modality but it has low sensitivity. Digital chest tomosynthesis (DCT) is an imaging modality that produces 3D images by collecting x-ray projection images over a limited angle. DCT is less expensive than CT and requires about 1/10th the dose of radiation. Commercial DCT systems acquire the projection images by mechanically scanning an x-ray tube. The movement of the tube head limits acquisition speed. We recently demonstrated the feasibility of stationary digital chest tomosynthesis (s-DCT) using a carbon nanotube (CNT) x-ray source array in benchtop phantom studies. The stationary x-ray source allows for fast image acquisition. The objective of this study is to demonstrate the feasibility of s-DCT for patient imaging. We have successfully imaged 31 patients. Preliminary evaluation by board certified radiologists suggests good depiction of thoracic anatomy and pathology.

  5. 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.

  6. Regulatory Compliance in Mammography.

    PubMed

    Loesch, Jennifer

    2016-03-01

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

  7. Digital tomosynthesis rendering of joint margins for arthritis assessment

    NASA Astrophysics Data System (ADS)

    Duryea, Jeffrey W.; Neumann, Gesa; Yoshioka, Hiroshi; Dobbins, James T., III

    2004-05-01

    PURPOSE: Rheumatoid arthritis (RA) of the hand is a significant healthcare problem. Techniques to accurately quantity the structural changes from RA are crucial for the development and prescription of therapies. Analysis of radiographic joint space width (JSW) is widely used and has demonstrated promise. However, radiography presents a 2D view of the joint. In this study we performed tomosynthesis reconstructions of proximal interphalangeal (PIP), and metacarpophalangeal (MCP) joints to measure the 3D joint structure. METHODS: We performed a reader study using simulated radiographs of 12 MCP and 12 PIP joints from skeletal specimens imaged with micro-CT. The tomosynthesis technique provided images of reconstructed planes with 0.75 mm spacing, which were presented to 2 readers with a computer tool. The readers were instructed to delineate the joint surfaces on tomosynthetic slices where they could visualize the margins. We performed a quantitative analysis of 5 slices surrounding the central portion of each joint. Reader-determined JSW was compared to a gold standard. As a figure of merit we calculated the average root-mean square deviation (RMSD). RESULTS: RMSD was 0.22 mm for both joints. For the individual joints, RMSD was 0.18 mm (MCP), and 0.26 mm (PIP). The reduced performance for the smaller PIP joints suggests that a slice spacing less than 0.75 mm may be more appropriate. CONCLUSIONS: We have demonstrated the capability of limited 3D rendering of joint surfaces using digital tomosynthesis. This technique promises to provide an improved method to visualize the structural changes of RA.

  8. Tomosynthesis applied to digital subtraction angiography

    SciTech Connect

    Kruger, R.A.; Sedaghati, M.; Roy, D.G.; Liu, P.; Nelson, J.A.; Kubal, W.; Del Rio, P.

    1984-09-01

    This extension of the author's previous work on tomographic digital subtraction angiography (DSA) describes the theory of tomosynthetic DSA image reconstruction techniques. In addition to developing the resolution limits resulting from x-ray exposure length and image intensifier field curvature, the authors describe one method of image formation and show tomosynthetic DSA images of animal and human anatomy. Methods for improving the present technique are discussed.

  9. Voting strategy for artifact reduction in digital breast tomosynthesis

    SciTech Connect

    Wu Tao; Moore, Richard H.; Kopans, Daniel B.

    2006-07-15

    Artifacts are observed in digital breast tomosynthesis (DBT) reconstructions due to the small number of projections and the narrow angular range that are typically employed in tomosynthesis imaging. In this work, we investigate the reconstruction artifacts that are caused by high-attenuation features in breast and develop several artifact reduction methods based on a 'voting strategy'. The voting strategy identifies the projection(s) that would introduce artifacts to a voxel and rejects the projection(s) when reconstructing the voxel. Four approaches to the voting strategy were compared, including projection segmentation, maximum contribution deduction, one-step classification, and iterative classification. The projection segmentation method, based on segmentation of high-attenuation features from the projections, effectively reduces artifacts caused by metal and large calcifications that can be reliably detected and segmented from projections. The other three methods are based on the observation that contributions from artifact-inducing projections have higher value than those from normal projections. These methods attempt to identify the projection(s) that would cause artifacts by comparing contributions from different projections. Among the three methods, the iterative classification method provides the best artifact reduction; however, it can generate many false positive classifications that degrade the image quality. The maximum contribution deduction method and one-step classification method both reduce artifacts well from small calcifications, although the performance of artifact reduction is slightly better with the one-step classification. The combination of one-step classification and projection segmentation removes artifacts from both large and small calcifications.

  10. Tomosynthesis-detected Architectural Distortion: Management Algorithm with Radiologic-Pathologic Correlation.

    PubMed

    Durand, Melissa A; Wang, Steven; Hooley, Regina J; Raghu, Madhavi; Philpotts, Liane E

    2016-01-01

    As use of digital breast tomosynthesis becomes increasingly widespread, new management challenges are inevitable because tomosynthesis may reveal suspicious lesions not visible at conventional two-dimensional (2D) full-field digital mammography. Architectural distortion is a mammographic finding associated with a high positive predictive value for malignancy. It is detected more frequently at tomosynthesis than at 2D digital mammography and may even be occult at conventional 2D imaging. Few studies have focused on tomosynthesis-detected architectural distortions to date, and optimal management of these distortions has yet to be well defined. Since implementing tomosynthesis at our institution in 2011, we have learned some practical ways to assess architectural distortion. Because distortions may be subtle, tomosynthesis localization tools plus improved visualization of adjacent landmarks are crucial elements in guiding mammographic identification of elusive distortions. These same tools can guide more focused ultrasonography (US) of the breast, which facilitates detection and permits US-guided tissue sampling. Some distortions may be sonographically occult, in which case magnetic resonance imaging may be a reasonable option, both to increase diagnostic confidence and to provide a means for image-guided biopsy. As an alternative, tomosynthesis-guided biopsy, conventional stereotactic biopsy (when possible), or tomosynthesis-guided needle localization may be used to achieve tissue diagnosis. Practical uses for tomosynthesis in evaluation of architectural distortion are highlighted, potential complications are identified, and a working algorithm for management of tomosynthesis-detected architectural distortion is proposed. (©)RSNA, 2016. PMID:26963448

  11. Adapted fan-beam volume reconstruction for stationary digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Wu, Gongting; Inscoe, Christine; Calliste, Jabari; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

    2015-03-01

    Digital breast tomosynthesis (DBT) provides 3D images which remove tissue overlapping and enables better cancer detection. Stationary DBT (s-DBT) uses a fixed X-ray source array to eliminate image blur associated with the x-ray tube motion and provides better image quality as well as faster scanning speed. For limited angle tomography, it is known that iterative reconstructions generally produces better images with fewer artifacts. However classical iterative tomosynthesis reconstruction methods are considerably slower than the filtered back-projection (FBP) reconstruction. The linear x-ray source array used in s-DBT enables a computationally more efficient volume reconstruction using adapted fan beam slice sampling, which transforms the 3-D cone beam reconstruction to a series of 2-D fan beam slice reconstructions. In this paper, we report the first results of the adapted fan-beam volume reconstruction (AFVR) for the s-DBT system currently undergoing clinical trial at UNC, using a simultaneous algebraic reconstruction technique (SART). An analytic breast phantom is used to quantitatively analyze the performance of the AFVR. Image quality of a CIRS biopsy phantom reconstructed using the AFVR method are compared to that using FBP algorithm with a commercial package. Our results show a significant reduction in memory usage and an order of magnitude speed increase in reconstructing speed using AFVR compared to that of classical 3-D cone beam reconstruction. We also observed that images reconstructed by AFVR with SART had a better sharpness and contrast compared to that using FBP. Preliminary results on patient images demonstrates the improved detectability of the s-DBT system over the mammography. By utilizing parallel computing with graphics processing unit (GPU), it is expected that the AFVR method will enable iterative reconstruction technique to be practical for clinical applications.

  12. A task-based comparison of two reconstruction algorithms for digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Mahadevan, Ravi; Ikejimba, Lynda C.; Lin, Yuan; Samei, Ehsan; Lo, Joseph Y.

    2014-03-01

    Digital breast tomosynthesis (DBT) generates 3-D reconstructions of the breast by taking X-Ray projections at various angles around the breast. DBT improves cancer detection as it minimizes tissue overlap that is present in traditional 2-D mammography. In this work, two methods of reconstruction, filtered backprojection (FBP) and the Newton-Raphson iterative reconstruction were used to create 3-D reconstructions from phantom images acquired on a breast tomosynthesis system. The task based image analysis method was used to compare the performance of each reconstruction technique. The task simulated a 10mm lesion within the breast containing iodine concentrations between 0.0mg/ml and 8.6mg/ml. The TTF was calculated using the reconstruction of an edge phantom, and the NPS was measured with a structured breast phantom (CIRS 020) over different exposure levels. The detectability index d' was calculated to assess image quality of the reconstructed phantom images. Image quality was assessed for both conventional, single energy and dual energy subtracted reconstructions. Dose allocation between the high and low energy scans was also examined. Over the full range of dose allocations, the iterative reconstruction yielded a higher detectability index than the FBP for single energy reconstructions. For dual energy subtraction, detectability index was maximized when most of the dose was allocated to the high energy image. With that dose allocation, the performance trend for reconstruction algorithms reversed; FBP performed better than the corresponding iterative reconstruction. However, FBP performance varied very erratically with changing dose allocation. Therefore, iterative reconstruction is preferred for both imaging modalities despite underperforming dual energy FBP, as it provides stable results.

  13. Fusion of digital breast tomosynthesis images via wavelet synthesis for improved lesion conspicuity

    NASA Astrophysics Data System (ADS)

    Hariharan, Harishwaran; Pomponiu, Victor; Zheng, Bin; Whiting, Bruce; Gur, David

    2014-03-01

    Full-field digital mammography (FFDM) is the most common screening procedure for detecting early breast cancer. However, due to complications such as overlapping breast tissue in projection images, the efficacy of FFDM reading is reduced. Recent studies have shown that digital breast tomosynthesis (DBT), in combination with FFDM, increases detection sensitivity considerably while decreasing false-positive, recall rates. There is a huge interest in creating diagnostically accurate 2-D interpretations from the DBT slices. Most of the 2-D syntheses rely on visualizing the maximum intensities (brightness) from each slice through different methods. We propose a wavelet based fusion method, where we focus on preserving holistic information from larger structures such as masses while adding high frequency information that is relevant and helpful for diagnosis. This method enables the spatial generation of a 2D image from a series of DBT images, each of which contains both smooth and coarse structures distributed in the wavelet domain. We believe that the wavelet-synthesized images, generated from their DBT image datasets, provide radiologists with improved lesion and micro-calcification conspicuity as compared with FFDM images. The potential impact of this fusion method is (1) Conception of a device-independent, data-driven modality that increases the conspicuity of lesions, thereby facilitating early detection and potentially reducing recall rates; (2) Reduction of the accompanying radiation dose to the patient.

  14. Dual-energy contrast enhanced digital breast tomosynthesis: concept, method, and evaluation on phantoms

    NASA Astrophysics Data System (ADS)

    Puong, Sylvie; Patoureaux, Fanny; Iordache, Razvan; Bouchevreau, Xavier; Muller, Serge

    2007-03-01

    In this paper, we present the development of dual-energy Contrast-Enhanced Digital Breast Tomosynthesis (CEDBT). A method to produce background clutter-free slices from a set of low and high-energy projections is introduced, along with a scheme for the determination of the optimal low and high-energy techniques. Our approach consists of a dual-energy recombination of the projections, with an algorithm that has proven its performance in Contrast-Enhanced Digital Mammography1 (CEDM), followed by an iterative volume reconstruction. The aim is to eliminate the anatomical background clutter and to reconstruct slices where the gray level is proportional to the local iodine volumetric concentration. Optimization of the low and high-energy techniques is performed by minimizing the total glandular dose to reach a target iodine Signal Difference to Noise Ratio (SDNR) in the slices. In this study, we proved that this optimization could be done on the projections, by consideration of the SDNR in the projections instead of the SDNR in the slices, and verified this with phantom measurements. We also discuss some limitations of dual-energy CEDBT, due to the restricted angular range for the projection views, and to the presence of scattered radiation. Experiments on textured phantoms with iodine inserts were conducted to assess the performance of dual-energy CEDBT. Texture contrast was nearly completely removed and the iodine signal was enhanced in the slices.

  15. Automated detection of microcalcification clusters for digital breast tomosynthesis using projection data only: A preliminary study

    SciTech Connect

    Reiser, I.; Nishikawa, R. M.; Edwards, A. V.; Kopans, D. B.; Schmidt, R. A.; Papaioannou, J.; Moore, R. H.

    2008-04-15

    Digital breast tomosynthesis (DBT) is a promising modality for breast imaging in which an anisotropic volume image of the breast is obtained. We present an algorithm for computerized detection of microcalcification clusters (MCCs) for DBT. This algorithm operates on the projection views only. Therefore it does not depend on reconstruction, and is computationally efficient. The algorithm was developed using a database of 30 image sets with microcalcifications, and a control group of 30 image sets without visible findings. The patient data were acquired on the first DBT prototype at Massachusetts General Hospital. Algorithm sensitivity was estimated to be 0.86 at 1.3 false positive clusters, which is below that of current MCC detection algorithms for full-field digital mammography. Because of the small number of patient cases, algorithm parameters were not optimized and one linear classifier was used. An actual limitation of our approach may be that the signal-to-noise ratio in the projection images is too low for microcalcification detection. Furthermore, the database consisted of predominantly small MCC. This may be related to the image quality obtained with this first prototype.

  16. Cancer risk estimation in Digital Breast Tomosynthesis using GEANT4 Monte Carlo simulations and voxel phantoms.

    PubMed

    Ferreira, P; Baptista, M; Di Maria, S; Vaz, P

    2016-05-01

    The aim of this work was to estimate the risk of radiation induced cancer following the Portuguese breast screening recommendations for Digital Mammography (DM) when applied to Digital Breast Tomosynthesis (DBT) and to evaluate how the risk to induce cancer could influence the energy used in breast diagnostic exams. The organ doses were calculated by Monte Carlo simulations using a female voxel phantom and considering the acquisition of 25 projection images. Single organ cancer incidence risks were calculated in order to assess the total effective radiation induced cancer risk. The screening strategy techniques considered were: DBT in Cranio-Caudal (CC) view and two-view DM (CC and Mediolateral Oblique (MLO)). The risk of cancer incidence following the Portuguese screening guidelines (screening every two years in the age range of 50-80years) was calculated by assuming a single CC DBT acquisition view as standalone screening strategy and compared with two-view DM. The difference in the total effective risk between DBT and DM is quite low. Nevertheless in DBT an increase of risk for the lung is observed with respect to DM. The lung is also the organ that is mainly affected when non-optimal beam energy (in terms of image quality and absorbed dose) is used instead of an optimal one. The use of non-optimal energies could increase the risk of lung cancer incidence by a factor of about 2. PMID:27133140

  17. An experimental study of practical computerized scatter correction methods for prototype digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kim, H.; Park, H.; Choi, J.; Choi, Y.

    2014-03-01

    Digital breast tomosynthesis (DBT) is a technique developed to overcome the limitations of conventional digital mammography by reconstructing slices through the breast from projections acquired at different angles. In developing and optimizing DBT, the x-ray scatter reduction technique remains a significant challenge due to projection geometry and radiation dose limitations. The most common approach for scatter reduction technique is a beam-stop-array (BSA) algorithm while this method has a concern of additional exposure to acquire the scatter distribution. The compressed breast is roughly symmetry and the scatter profiles from projection acquired at axially opposite angle are similar to mirror image from each other. The purpose of this study was to apply the BSA algorithm acquiring only two scans with a beam stop array, which estimates scatter distribution with minimum additional exposure. The results of scatter correction with angular interpolation were comparable to those of scatter correction with all scatter distributions at each angle and exposure increase was less than 13%. This study demonstrated the influence of scatter correction by BSA algorithm with minimum exposure which indicates the practical application in clinical situations.

  18. Scatter characterization using a beam-stop-array algorithm for digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Digital breast tomosynthesis (DBT) is a technique developed to overcome the limitations of conventional digital mammography by reconstructing slices through the breast from projections acquired at different angles from the X-ray source. In the development and the optimization of DBT, the X-ray scatter reduction technique remains a significant challenge due to projectiongeometry and radiation-dose concerns. The purpose of this study was to apply the scatter correction method, which estimates scatter patterns with a beam-stop-array (BSA) by spatial interpolation and obtains primary projections by subtracting the scatter patterns from raw detected projections. The DBT prototype is based on the CsI phosphor/Complementary metal-oxide-semiconductor flat panel detector, which was optimized for low exposures with rapid readout. A simplified beam-stop-array algorithm was used to estimate the scatter pattern for each projection and to obtain only primary projections. We evaluated the distribution of the scatter intensity by using a BSA algorithm and reconstructed breast images based on projections with and without a scatter correction. Comparing corrected and uncorrected slices, we measured the linear attenuation coefficient (LAC) over a breast phantom. These quantitative comparisons indicated improved image quality in terms of contrast, background noise and contrast-to-noise ratio.

  19. Parenchymal Texture Analysis in Digital Breast Tomosynthesis for Breast Cancer Risk Estimation: A Preliminary Study

    PubMed Central

    Kontos, Despina; Bakic, Predrag R.; Carton, Ann-Katherine; Troxel, Andrea B.; Conant, Emily F.; Maidment, Andrew D.A.

    2009-01-01

    Rationale and Objectives Studies have demonstrated a relationship between mammographic parenchymal texture and breast cancer risk. Although promising, texture analysis in mammograms is limited by tissue superimposition. Digital breast tomosynthesis (DBT) is a novel tomographic x-ray breast imaging modality that alleviates the effect of tissue superimposition, offering superior parenchymal texture visualization compared to mammography. Our study investigates the potential advantages of DBT parenchymal texture analysis for breast cancer risk estimation. Materials and Methods DBT and digital mammography (DM) images of 39 women were analyzed. Texture features, shown in studies with mammograms to correlate with cancer risk, were computed from the retroareolar breast region. We compared the relative performance of DBT and DM texture features in correlating with two measures of breast cancer risk: (i) the Gail and Claus risk estimates, and (ii) mammographic breast density. Linear regression was performed to model the association between texture features and increasing levels of risk. Results No significant correlation was detected between parenchymal texture and the Gail and Claus risk estimates. Significant correlations were observed between texture features and breast density. Overall, the DBT texture features demonstrated stronger correlations with breast percent density (PD) than DM (p ≤0.05). When dividing our study population in groups of increasing breast PD, the DBT texture features appeared to be more discriminative, having regression lines with overall lower p-values, steeper slopes, and higher R2 estimates. Conclusion Although preliminary, our results suggest that DBT parenchymal texture analysis could provide more accurate characterization of breast density patterns, which could ultimately improve breast cancer risk estimation. PMID:19201357

  20. Digital breast tomosynthesis (DBT): a review of the evidence for use as a screening tool.

    PubMed

    Gilbert, Fiona J; Tucker, Lorraine; Young, Ken C

    2016-02-01

    Breast screening with full-field digital mammography (FFDM) fails to detect 15-30% of cancers. This figure is higher for women with dense breasts. A new tomographic technique in mammography has been developed--digital breast tomosynthesis (DBT)--which allows images to be viewed in sections through the breast and has the potential to improve cancer detection rates. Results from retrospective reading studies comparing DBT with FFDM have been largely favourable with improvement in sensitivity and specificity. Increases in diagnostic accuracy have been reported as being independent of breast density; however there are mixed reports regarding the detection of microcalcification. Prospective screening studies using DBT with FFDM have demonstrated increased rates in cancer detection compared with FFDM alone. A reduction in false-positive recall rates has also been shown. Screening with the addition of DBT would approximately double radiation dose; however a simulated FFDM image can be generated from a DBT scan. The combination of simulated FFDM images and DBT is being evaluated within several studies and some positive results have been published. Interval cancer rates for the UK National Health Service Breast Screening Programme (NHSBSP) demonstrate the limited sensitivity of FFDM in cancer detection. DBT has the potential to increase sensitivity and decrease false-positive recall rates. It has approval for screening and diagnostics in several countries; however, there are issues with DBT as a screening tool including additional reading time, IT storage and connectivity, over-diagnosis, and cost effectiveness. Feasibility and cost-effectiveness trials are needed before the implementation of DBT in NHSBSP can be considered. PMID:26707815

  1. Fast microcalcification detection on digital breast tomosynthesis datasets

    NASA Astrophysics Data System (ADS)

    Bernard, S.; Muller, S.; Peters, G.; Iordache, R.

    2007-03-01

    In this paper, we present a fast method for microcalcification detection in Digital Breast Tomosynthesis. Instead of applying the straight-forward reconstruction/filtering/thresholding approach, the filtering is performed on projections before simple back-projection reconstruction. This leads to a reduced computation time since the number of projections is generally much smaller than the number of slices. For an average breast thickness and a typical number of projections, the number of operations is reduced by a factor in the range of 2 to 4. At the same time, the approach yields a negligible decrease of the contrast to noise ratio in the reconstructed slices. Image segmentation results are presented and compared to the previous method as visual performance assessment.

  2. Generalized filtered back-projection for digital breast tomosynthesis reconstruction

    NASA Astrophysics Data System (ADS)

    Erhard, Klaus; Grass, Michael; Hitziger, Sebastian; Iske, Armin; Nielsen, Tim

    2012-03-01

    Filtered backprojection (FBP) has been commonly used as an efficient and robust reconstruction technique in tomographic X-ray imaging during the last decades. For standard geometries like circle or helix it is known how to efficiently filter the data. However, for geometries with only few projection views or with a limited angular range, the application of FBP algorithms generally provides poor results. In digital breast tomosynthesis (DBT) these limitations give rise to image artifacts due to the limited angular range and the coarse angular sampling. In this work, a generalized FBP algorithm is presented, which uses the filtered projection data of all acquired views for backprojection along one direction. The proposed method yields a computationally efficient generalized FBP algorithm for DBT, which provides similar image quality as iterative reconstruction techniques while preserving the ability for region of interest reconstructions. To demonstrate the excellent performance of this method, examples are given with a simulated breast phantom and the hardware BR3D phantom.

  3. Estimates of Average Glandular Dose with Auto-modes of X-ray Exposures in Digital Breast Tomosynthesis

    PubMed Central

    Kamal, Izdihar; Chelliah, Kanaga K.; Mustafa, Nawal

    2015-01-01

    Objectives: The aim of this research was to examine the average glandular dose (AGD) of radiation among different breast compositions of glandular and adipose tissue with auto-modes of exposure factor selection in digital breast tomosynthesis. Methods: This experimental study was carried out in the National Cancer Society, Kuala Lumpur, Malaysia, between February 2012 and February 2013 using a tomosynthesis digital mammography X-ray machine. The entrance surface air kerma and the half-value layer were determined using a 100H thermoluminescent dosimeter on 50% glandular and 50% adipose tissue (50/50) and 20% glandular and 80% adipose tissue (20/80) commercially available breast phantoms (Computerized Imaging Reference Systems, Inc., Norfolk, Virginia, USA) with auto-time, auto-filter and auto-kilovolt modes. Results: The lowest AGD for the 20/80 phantom with auto-time was 2.28 milliGray (mGy) for two dimension (2D) and 2.48 mGy for three dimensional (3D) images. The lowest AGD for the 50/50 phantom with auto-time was 0.97 mGy for 2D and 1.0 mGy for 3D. Conclusion: The AGD values for both phantoms were lower against a high kilovolt peak and the use of auto-filter mode was more practical for quick acquisition while limiting the probability of operator error. PMID:26052465

  4. Lung cancer detection with digital chest tomosynthesis: first round results from the SOS observational study

    PubMed Central

    Viti, Andrea; Tavella, Chiara; Priotto, Roberto; Ghirardo, Donatella; Grosso, Maurizio; Terzi, Alberto

    2015-01-01

    Objective Baseline results of the Studio OSservazionale (SOS), observational study, a single-arm observational study of digital chest tomosynthesis for lung cancer detection in an at-risk population demonstrated a detection rate of lung cancer comparable to that of studies that used low dose CT scan (LDCT). We present the results of the first round. Methods Totally 1,703 out of 1,843 (92%) subjects who had a baseline digital chest tomosynthesis underwent a first round reevaluation after 1 year. Results At first round chest digital tomosynthesis, 13 (0.7%) subjects had an indeterminate nodule larger than 5 mm and underwent low-dose CT scan for nodule confirmation. PET/CT study was obtained in 10 (0.5%) subjects and 2 subjects had a low-dose CT follow up. Surgery, either video-assisted thoracoscopic or open surgery for indeterminate pulmonary nodules was performed in 10 (0.2%) subjects. A lung cancer was diagnosed and resected in five patients. The lung cancer detection rate at first round was 0.3% (5/1,703). Conclusions The detection rate of lung cancer at first round for tomosynthesis is comparable to rates reported for CT. In addition, results of first round digital chest tomosynthesis confirm chest tomosynthesis as a possible first-line lung cancer-screening tool. PMID:25992366

  5. 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.

  6. Anatomical decomposition in dual energy chest digital tomosynthesis

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Lung cancer is the leading cause of cancer death worldwide and the early diagnosis of lung cancer has recently become more important. For early screening lung cancer, computed tomography (CT) has been used as a gold standard for early diagnosis of lung cancer [1]. The major advantage of CT is that it is not susceptible to the problem of misdiagnosis caused by anatomical overlapping while CT has extremely high radiation dose and cost compared to chest radiography. Chest digital tomosynthesis (CDT) is a recently introduced new modality for lung cancer screening with relatively low radiation dose compared to CT [2] and also showing high sensitivity and specificity to prevent anatomical overlapping occurred in chest radiography. Dual energy material decomposition method has been proposed for better detection of pulmonary nodules as means of reducing the anatomical noise [3]. In this study, possibility of material decomposition in CDT was tested by simulation study and actual experiment using prototype CDT. Furthermore organ absorbed dose and effective dose were compared with single energy CDT. The Gate v6 (Geant4 application for tomographic emission), and TASMIP (Tungsten anode spectral model using the interpolating polynomial) code were used for simulation study and simulated cylinder shape phantom consisted of 4 inner beads which were filled with spine, rib, muscle and lung equivalent materials. The patient dose was estimated by PCXMC 1.5 Monte Carlo simulation tool [4]. The tomosynthesis scan was performed with a linear movement and 21 projection images were obtained over 30 degree of angular range with 1.5° degree of angular interval. The proto type CDT system has same geometry with simulation study and composed of E7869X (Toshiba, Japan) x-ray tube and FDX3543RPW (Toshiba, Japan) detector. The result images showed that reconstructed with dual energy clearly visualize lung filed by removing unnecessary bony structure. Furthermore, dual energy CDT could enhance

  7. Evaluation of time-efficient reconstruction methods in digital breast tomosynthesis.

    PubMed

    Svahn, T M; Houssami, N

    2015-07-01

    Three reconstruction algorithms for digital breast tomosynthesis were compared in this article: filtered back-projection (FBP), iterative adapted FBP and maximum likelihood-convex iterative algorithms. Quality metrics such as signal-difference-to-noise ratio, normalised line-profiles and artefact-spread function were used for evaluation of reconstructed tomosynthesis images. The iterative-based methods offered increased image quality in terms of higher detectability and reduced artefacts, which will be further examined in clinical images. PMID:25855075

  8. Breast tissue classification in digital tomosynthesis images based on global gradient minimization and texture features

    NASA Astrophysics Data System (ADS)

    Qin, Xulei; Lu, Guolan; Sechopoulos, Ioannis; Fei, Baowei

    2014-03-01

    Digital breast tomosynthesis (DBT) is a pseudo-three-dimensional x-ray imaging modality proposed to decrease the effect of tissue superposition present in mammography, potentially resulting in an increase in clinical performance for the detection and diagnosis of breast cancer. Tissue classification in DBT images can be useful in risk assessment, computer-aided detection and radiation dosimetry, among other aspects. However, classifying breast tissue in DBT is a challenging problem because DBT images include complicated structures, image noise, and out-of-plane artifacts due to limited angular tomographic sampling. In this project, we propose an automatic method to classify fatty and glandular tissue in DBT images. First, the DBT images are pre-processed to enhance the tissue structures and to decrease image noise and artifacts. Second, a global smooth filter based on L0 gradient minimization is applied to eliminate detailed structures and enhance large-scale ones. Third, the similar structure regions are extracted and labeled by fuzzy C-means (FCM) classification. At the same time, the texture features are also calculated. Finally, each region is classified into different tissue types based on both intensity and texture features. The proposed method is validated using five patient DBT images using manual segmentation as the gold standard. The Dice scores and the confusion matrix are utilized to evaluate the classified results. The evaluation results demonstrated the feasibility of the proposed method for classifying breast glandular and fat tissue on DBT images.

  9. Effect of the glandular composition on digital breast tomosynthesis image quality and dose optimisation.

    PubMed

    Marques, T; Ribeiro, A; Di Maria, S; Belchior, A; Cardoso, J; Matela, N; Oliveira, N; Janeiro, L; Almeida, P; Vaz, P

    2015-07-01

    In the image quality assessment for digital breast tomosynthesis (DBT), a breast phantom with an average percentage of 50 % glandular tissue is seldom used, which may not be representative of the breast tissue composition of the women undergoing such examination. This work aims at studying the effect of the glandular composition of the breast on the image quality taking into consideration different sizes of lesions. Monte Carlo simulations were performed using the state-of-the-art computer program PENELOPE to validate the image acquisition system of the DBT equipment as well as to calculate the mean glandular dose for each projection image and for different breast compositions. The integrated PENELOPE imaging tool (PenEasy) was used to calculate, in mammography, for each clinical detection task the X-ray energy that maximises the figure of merit. All the 2D cranial-caudal projections for DBT were simulated and then underwent the reconstruction process applying the Simultaneous Algebraic Reconstruction Technique. Finally, through signal-to-noise ratio analysis, the image quality in DBT was assessed. PMID:25836692

  10. Feasibility of Amorphous Selenium Based Photon Counting Detectors for Digital Breast Tomosynthesis

    SciTech Connect

    Chen, J.; O'Connor, P.; Lehnert, J., De Geronimo, G., Dolazza, E., Tousignant, O., Laperriere, L., Greenspan, J., Zhao, W.

    2009-02-27

    Amorphous selenium (a-Se) has been incorporated successfully in direct conversion flat panel x-ray detectors, and has demonstrated superior image quality in screening mammography and digital breast tomosynthesis (DBT) under energy integration mode. The present work explores the potential of a-Se for photon counting detectors in DBT. We investigated major factors contributing to the variation in the charge collected by a pixel upon absorption of each x-ray photon. These factors included x-ray photon interaction, detector geometry, charge transport, and the pulse shaping and noise properties of the photon counting readout circuit. Experimental measurements were performed on a linear array test structure constructed by evaporating an a-Se layer onto an array of 100 {mu}m pitch strip electrodes, which are connected to a 32 channel low noise photon counting integrated circuit. The measured pulse height spectrum (PHS) under polychromatic xray exposure was interpreted quantitatively using the factors identified. Based on the understanding of a-Se photon counting performance, design parameters were proposed for a 2D detector with high quantum efficiency and count rate that could meet the requirements of photon counting detector for DBT.

  11. Investigation of Megavoltage Digital Tomosynthesis using a Cobalt-60 Source

    NASA Astrophysics Data System (ADS)

    MacDonald, Amy

    The ability for megavoltage computed tomography patient setup verification using a cobalt-60 (Co-60) gamma ray source has been established in the context of cobalt tomotherapy. However, it would be beneficial to establish improved cobalt imaging that could be used on more conventional units. In terms of safety and efficiency, this imaging technique would provide the patient with less exposure to radiation. Digital tomosynthesis (DT) is an imaging modality that may provide improved depth localization and in-plane visibility compared to conventional portal imaging in modern Co-60 radiation therapy. DT is a practical and efficient method of achieving depth localization from a limited gantry rotation and a limited number of projections. In DT, each plane of the imaging volume can be brought into focus by relatively displacing the composite images and superimposing the shifted dataset according to the acquisition geometry. Digital flat-panel technology has replaced the need for multiple film exposures and therefore the speed of imaging and capabilities for image processing has put DT in the forefront of both clinical and industrial imaging applications. The objective of this work is to develop and evaluate the performance of an experimental system for megavoltage digital tomosynthesis ( MVDT) imaging using a Co-60 gamma ray source. Linear and isocentric acquisition geometries are implemented using tomographic angles of 20--60° and 10--60 projections. Reconstruction algorithms are designed for both acquisition geometries. Using the backprojection approach, the data are shifted and added to reconstruct focal planes of interest. Depth localization and its dependence on tomographic angle and projection density are visualized with an anthropomorphic head phantom. High contrast resolution at localized depths is quantified using the modulation transfer function approach. Results show that focal-plane visibility is improved for larger tomographic angles and that focal

  12. 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.

  13. Accelerating reconstruction of reference digital tomosynthesis using graphics hardware

    SciTech Connect

    Yan Hui; Ren Lei; Godfrey, Devon J.; Yin Fangfang

    2007-10-15

    The successful implementation of digital tomosynthesis (DTS) for on-board image guided radiation therapy (IGRT) requires fast DTS image reconstruction. Both target and reference DTS image sets are required to support an image registration application for IGRT. Target images are usually DTS image sets reconstructed from on-board projections, which can be accomplished quickly using the conventional filtered backprojection algorithm. Reference images are DTS image sets reconstructed from digitally reconstructed radiographs (DRRs) previously generated from conventional planning CT data. Generating a set of DRRs from planning CT is relatively slow using the conventional ray-casting algorithm. In order to facilitate DTS reconstruction within a clinically acceptable period of time, we implemented a high performance DRR reconstruction algorithm on a graphics processing unit of commercial PC graphics hardware. The performance of this new algorithm was evaluated and compared with that which is achieved using the conventional software-based ray-casting algorithm. DTS images were reconstructed from DRRs previously generated by both hardware and software algorithms. On average, the DRR reconstruction efficiency using the hardware method is improved by a factor of 67 over the software method. The image quality of the DRRs was comparable to those generated using the software-based ray-casting algorithm. Accelerated DRR reconstruction significantly reduces the overall time required to produce a set of reference DTS images from planning CT and makes this technique clinically practical for target localization for radiation therapy.

  14. DART, a platform for the creation and registration of cone beam digital tomosynthesis datasets.

    PubMed

    Sarkar, Vikren; Shi, Chengyu; Papanikolaou, Niko

    2011-04-01

    Digital tomosynthesis is an imaging modality that allows for tomographic reconstructions using only a fraction of the images needed for CT reconstruction. Since it offers the advantages of tomographic images with a smaller imaging dose delivered to the patient, the technique offers much promise for use in patient positioning prior to radiation delivery. This paper describes a software environment developed to help in the creation of digital tomosynthesis image sets from digital portal images using three different reconstruction algorithms. The software then allows for use of the tomograms for patient positioning or for dose recalculation if shifts are not applied, possibly as part of an adaptive radiotherapy regimen. PMID:21161469

  15. Contrast-Enhanced Digital Mammography and Angiogenesis

    SciTech Connect

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

    2007-11-26

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

  16. Characterizing X-ray detectors for prototype digital breast tomosynthesis systems

    NASA Astrophysics Data System (ADS)

    Kim, Y.-s.; Park, H.-s.; Park, S.-J.; Choi, S.; Lee, H.; Lee, D.; Choi, Y.-W.; Kim, H.-J.

    2016-03-01

    The digital breast tomosynthesis (DBT) system is a newly developed 3-D imaging technique that overcomes the tissue superposition problems of conventional mammography. Therefore, it produces fewer false positives. In DBT system, several parameters are involved in image acquisition, including geometric components. A series of projections should be acquired at low exposure. This makes the system strongly dependent on the detector's characteristic performance. This study compares two types of x-ray detectors developed by the Korea Electrotechnology Research Institute (KERI). The first prototype DBT system has a CsI (Tl) scintillator/CMOS based flat panel digital detector (2923 MAM, Dexela Ltd.), with a pixel size of 0.0748 mm. The second uses a-Se based direct conversion full field detector (AXS 2430, analogic) with a pixel size of 0.085 mm. The geometry of both systems is same, with a focal spot 665.8 mm from the detector, and a center of rotation 33 mm above the detector surface. The systems were compared with regard to modulation transfer function (MTF), normalized noise power spectrum (NNPS), detective quantum efficiency (DQE) and a new metric, the relative object detectability (ROD). The ROD quantifies the relative performance of each detector at detecting specified objects. The system response function demonstrated excellent linearity (R2>0.99). The CMOS-based detector had a high sensitivity, while the Anrad detector had a large dynamic range. The higher MTF and noise power spectrum (NPS) values were measured using an Anrad detector. The maximum DQE value of the Dexela detector was higher than that of the Anrad detector with a low exposure level, considering one projection exposure for tomosynthesis. Overall, the Dexela detector performed better than did the Anrad detector with regard to the simulated Al wires, spheres, test objects of ROD with low exposure level. In this study, we compared the newly developed prototype DBT system with two different types of x

  17. Comparison study of reconstruction algorithms for prototype digital breast tomosynthesis using various breast phantoms.

    PubMed

    Kim, Ye-seul; Park, Hye-suk; Lee, Haeng-Hwa; Choi, Young-Wook; Choi, Jae-Gu; Kim, Hak Hee; Kim, Hee-Joung

    2016-02-01

    Digital breast tomosynthesis (DBT) is a recently developed system for three-dimensional imaging that offers the potential to reduce the false positives of mammography by preventing tissue overlap. Many qualitative evaluations of digital breast tomosynthesis were previously performed by using a phantom with an unrealistic model and with heterogeneous background and noise, which is not representative of real breasts. The purpose of the present work was to compare reconstruction algorithms for DBT by using various breast phantoms; validation was also performed by using patient images. DBT was performed by using a prototype unit that was optimized for very low exposures and rapid readout. Three algorithms were compared: a back-projection (BP) algorithm, a filtered BP (FBP) algorithm, and an iterative expectation maximization (EM) algorithm. To compare the algorithms, three types of breast phantoms (homogeneous background phantom, heterogeneous background phantom, and anthropomorphic breast phantom) were evaluated, and clinical images were also reconstructed by using the different reconstruction algorithms. The in-plane image quality was evaluated based on the line profile and the contrast-to-noise ratio (CNR), and out-of-plane artifacts were evaluated by means of the artifact spread function (ASF). Parenchymal texture features of contrast and homogeneity were computed based on reconstructed images of an anthropomorphic breast phantom. The clinical images were studied to validate the effect of reconstruction algorithms. The results showed that the CNRs of masses reconstructed by using the EM algorithm were slightly higher than those obtained by using the BP algorithm, whereas the FBP algorithm yielded much lower CNR due to its high fluctuations of background noise. The FBP algorithm provides the best conspicuity for larger calcifications by enhancing their contrast and sharpness more than the other algorithms; however, in the case of small-size and low

  18. Optimizing configuration parameters of a stationary digital breast tomosynthesis system based on carbon nanotube x-ray sources

    NASA Astrophysics Data System (ADS)

    Tucker, Andrew; Qian, Xin; Gidcumb, Emily; Spronk, Derrek; Sprenger, Frank; Kuo, Johnny; Ng, Susan; Lu, Jianping; Zhou, Otto

    2012-03-01

    The stationary Digital Breast Tomosynthesis System (s-DBT) has the advantage over the conventional DBT systems as there is no motion blurring in the projection images associated with the x-ray source motion. We have developed a prototype s-DBT system by retrofitting a Hologic Selenia Dimensions rotating gantry tomosynthesis system with a distributed carbon nanotube (CNT) x-ray source array. The linear array consists of 31 x-ray generating focal spots distributed over a 30 degree angle. Each x-ray beam can be electronically activated allowing the flexibility and easy implementation of novel tomosynthesis scanning with different scanning parameters and configurations. Here we report the initial results of investigation on the imaging quality of the s-DBT system and its dependence on the acquisition parameters including the number of projections views, the total angular span of the projection views, the dose distribution between different projections, and the total dose. A mammography phantom is used to visually assess image quality. The modulation transfer function (MTF) of a line wire phantom is used to evaluate the system spatial resolution. For s-DBT the in-plan system resolution, as measured by the MTF, does not change for different configurations. This is in contrast to rotating gantry DBT systems, where the MTF degrades for increased angular span due to increased focal spot blurring associated with the x-ray source motion. The overall image quality factor, a composite measure of the signal difference to noise ratio (SdNR) for mass detection and the z-axis artifact spread function for microcalcification detection, is best for the configuration with a large angular span, an intermediate number of projection views, and an even dose distribution. These results suggest possible directions for further improvement of s-DBT systems for high quality breast cancer imaging.

  19. Radiologists' interpretive efficiency and variability in true- and false-positive detection when screen-reading with tomosynthesis (3D-mammography) relative to standard mammography in population screening.

    PubMed

    Svahn, Tony M; Macaskill, Petra; Houssami, Nehmat

    2015-12-01

    We examined interpretive efficiency and variability in true- and false-positive detection (TP, FP) for radiologists screen-reading with digital breast tomosynthesis as adjunct to full-field digital mammography (2D/3D) relative to 2D alone in population-based screening studies. A systematic literature search was performed to identify screening studies that provided radiologist-specific data for TP and FP detection. Radiologist interpretive efficiency (trade-off between TPs and FPs) was calculated using the FP:TP ratio which expresses the number of FP recalls for each screen-detected breast cancer. We modeled a pooled FP:TP ratio to assess variability in radiologists' interpretive efficiency at study-level using random effects logistic regression. FP:TP ratio improved (ratio decreased) for 2D/3D screen-reading (relative to 2D) for a majority of radiologists (18 of 22) across all studies. Variability in radiologists' FP:TP ratio was consistently lower in all studies for 2D/3D screen-reading, as suggested by lower variance in ratios. Study-level pooled FP:TP ratio for 2D- and 2D/3D-mammography respectively, were 5.96 (95%CI: 4.08 to 8.72) and 3.17 (95%CI: 2.25 to 4.47) for the STORM trial; 10.25 (95%CI: 6.42 to 16.35) and 7.07 (95%CI: 4.99 to 10.02) for the Oslo trial; and 20.84 (95%CI: 13.95 to 31.12) and 8.37 (95%CI: 5.87 to 11.93) for the Houston study. This transfers into study-level improved interpretative efficiencies of 48%, 30% and 55%, respectively, for 2D/3D screen-reading (relative to 2D). In summary, study-level FP:TP trade-off improved using 2D/3D-mammography for all studies, which was also seen for most individual radiologists. There was variability in the FP:TP trade-off between readers and studies for 2D-as well as for 2D/3D-interpretations but variability in radiologists' interpretive efficiency was relatively lower using 2D/3D-mammography. PMID:26433751

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  1. Geometric estimation method for x-ray digital intraoral tomosynthesis

    NASA Astrophysics Data System (ADS)

    Li, Liang; Yang, Yao; Chen, Zhiqiang

    2016-06-01

    It is essential for accurate image reconstruction to obtain a set of parameters that describes the x-ray scanning geometry. A geometric estimation method is presented for x-ray digital intraoral tomosynthesis (DIT) in which the detector remains stationary while the x-ray source rotates. The main idea is to estimate the three-dimensional (3-D) coordinates of each shot position using at least two small opaque balls adhering to the detector surface as the positioning markers. From the radiographs containing these balls, the position of each x-ray focal spot can be calculated independently relative to the detector center no matter what kind of scanning trajectory is used. A 3-D phantom which roughly simulates DIT was designed to evaluate the performance of this method both quantitatively and qualitatively in the sense of mean square error and structural similarity. Results are also presented for real data acquired with a DIT experimental system. These results prove the validity of this geometric estimation method.

  2. Digital breast tomosynthesis reconstruction with an adaptive voxel grid

    NASA Astrophysics Data System (ADS)

    Claus, Bernhard; Chan, Heang-Ping

    2014-03-01

    In digital breast tomosynthesis (DBT) volume datasets are typically reconstructed with an anisotropic voxel size, where the in-plane voxel size usually reflects the detector pixel size (e.g., 0.1 mm), and the slice separation is generally between 0.5-1.0 mm. Increasing the tomographic angle is expected to give better 3D image quality; however, the slice spacing in the reconstruction should be reduced, otherwise one may risk losing fine-scale image detail (e.g., small microcalcifications). An alternative strategy consists of reconstructing on an adaptive voxel grid, where the voxel height at each location is adapted based on the backprojected data at this location, with the goal to improve image quality for microcalcifications. In this paper we present an approach for generating such an adaptive voxel grid. This approach is based on an initial reconstruction step that is performed at a finer slice-spacing combined with a selection of an "optimal" height for each voxel. This initial step is followed by a (potentially iterative) reconstruction acting now on the adaptive grid only.

  3. Digital tomosynthesis in lung cancer: state of the art

    PubMed Central

    Viti, Andrea; Terzi, Alberto

    2015-01-01

    Chest digital tomosynthesis (CDT) is a limited angle image tomography, which improves the visibility of anatomy compared with radiographic imaging. Due to the limited acquisition angle of CDT, it has the potential to significantly increase the temporal resolution of patient surveillance at the cost of reduced resolution in one direction. CDT is 3 times more effective in identifying pulmonary nodules compared to conventional radiography and at lower doses and cost compared with routine chest computed tomography (CT) examinations. There is only one report in which CDT was used in a single-arm observational study for lung cancer detection in at-risk population while a few studies suggested that CDT sensitivity is superior to radiography but inferior to CT in detecting lung nodules, other studies on the accuracy of CDT suggest that the specificity is much closer to CT than radiography. Therefore, large-scale randomized controlled trial would be needed to confirm benefits of CDT and identify where it is best used in the clinical setting. CDT seems to be a cost-effectiveness first-line lung cancer screening tool to detect potential lung cancer nodule. PMID:26207232

  4. Fast reconstruction of digital tomosynthesis using on-board images

    SciTech Connect

    Yan Hui; Godfrey, Devon J.; Yin Fangfang

    2008-05-15

    Digital tomosynthesis (DTS) is a method to reconstruct pseudo three-dimensional (3D) volume images from two-dimensional x-ray projections acquired over limited scan angles. Compared with cone-beam computed tomography, which is frequently used for 3D image guided radiation therapy, DTS requires less imaging time and dose. Successful implementation of DTS for fast target localization requires the reconstruction process to be accomplished within tight clinical time constraints (usually within 2 min). To achieve this goal, substantial improvement of reconstruction efficiency is necessary. In this study, a reconstruction process based upon the algorithm proposed by Feldkamp, Davis, and Kress was implemented on graphics hardware for the purpose of acceleration. The performance of the novel reconstruction implementation was tested for phantom and real patient cases. The efficiency of DTS reconstruction was improved by a factor of 13 on average, without compromising image quality. With acceleration of the reconstruction algorithm, the whole DTS generation process including data preprocessing, reconstruction, and DICOM conversion is accomplished within 1.5 min, which ultimately meets clinical requirement for on-line target localization.

  5. Intravenous pyelogram artefacts unique to digital tomosynthesis reconstruction.

    PubMed

    Rowberry, B K; Galea, A

    2011-11-01

    Recent advances in technology have led to the realisation of digital tomosynthesis (DT) imaging in routine investigations such as intravenous pyelogram (IVP). The major advantage this technology has over other technologies is its ability to perform a retrospective reconstruction of an arbitrary number of coronal image planes from a single data set consisting of a series of low dose discrete projections acquired over a limited angular range using a stationary detector. It is well documented that because DT relies on an angular limited acquisition, the data set is incomplete. This, in combination with the image reconstruction algorithm, results in reconstructed images containing non-focused information from outside the immediate focal plane. This article describes and suggests the cause of two artefacts unique to DT that cannot be explained by blurring alone. We believe the two artefacts are caused by breathing during data acquisition together with a combination of other factors, including the anatomy of the renal system, the method of data acquisition and the reconstructive algorithm used. This could lead to the unaware reporting radiologist falsely diagnosing a duplex collecting system. To avoid these artefacts, we recommend DT IVP should only be used in patients who can adequately perform a breath-hold for the duration of the data acquisition. In addition, we suggest that the study should be performed with breath-held following expiration. PMID:22011833

  6. Focal spot calibration in a digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Choi, Jaegu; Hwang, Sun-Jo; Choi, Young-Wook

    2012-05-01

    Digital breast tomosynthesis (DBT) technology is a promising modality for the early detection of breast cancer and could provide clear diagnostic images in which the effect of tissue overlap is alleviated. Accurate calibration of the system geometry is essential for successful image reconstruction in DBT systems. The geometrical calibration of the focal spot in the X-ray tube at the detector plane is one of the most critical parameters of a DBT system. In this paper, a new method using a multi-hole collimator and an iterative calibration algorithm is reported in order to estimate the position of the focal spot at the detector plane. The iterative algorithm is based on the area-distance relationship in the collimator image. The linearity of this relationship has been verified both empirically and theoretically. A focal spot estimate has been achieved regardless of the location of the focal spot in the image. A total of 15 projection images acquired with the DBT system have been successfully reconstructed with geometric information about the focal spot position provided by our new method, and the focal spot estimate method proposed in this paper could be a useful solution for locating optical sources that cannot be viewed or accessed.

  7. Satellite teleradiology test bed for digital mammography

    NASA Astrophysics Data System (ADS)

    Barnett, Bruce G.; Dudding, Kathryn E.; Abdel-Malek, Aiman A.; Mitchell, Robert J.

    1996-05-01

    Teleradiology offers significant improvement in efficiency and patient compliance over current practices in traditional film/screen-based diagnosis. The increasing number of women who need to be screened for breast cancer, including those in remote rural regions, make the advantages of teleradiology especially attractive for digital mammography. At the same time, the size and resolution of digital mammograms are among the most challenging to support in a cost effective teleradiology system. This paper will describe a teleradiology architecture developed for use with digital mammography by GE Corporate Research and Development in collaboration with Massachusetts General Hospital under National Cancer Institute (NCI/NIH) grant number R01 CA60246-01. The testbed architecture is based on the Digital Imaging and Communications in Medicine (DICOM) standard, created by the American College of Radiology and National Electrical Manufacturers Association. The testbed uses several Sun workstations running SunOS, which emulate a rural examination facility connected to a central diagnostic facility, and uses a TCP-based DICOM application to transfer images over a satellite link. Network performance depends on the product of the bandwidth times the round- trip time. A satellite link has a round trip of 513 milliseconds, making the bandwidth-delay a significant problem. This type of high bandwidth, high delay network is called a Long Fat Network, or LFN. The goal of this project was to quantify the performance of the satellite link, and evaluate the effectiveness of TCP over an LFN. Four workstations have Sun's HSI/S (High Speed Interface) option. Two are connected by a cable, and two are connected through a satellite link. Both interfaces have the same T1 bandwidth (1.544 Megabits per second). The only difference was the round trip time. Even with large window buffers, the time to transfer a file over the satellite link was significantly longer, due to the bandwidth-delay. To

  8. The role of digital tomosynthesis in reducing the number of equivocal breast reportings

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Purpose To compare radiologists' confidence in assessing breast cancer using combined digital mammography (DM) and digital breast tomosynthesis (DBT) compared with DM alone as a function of previous experience with DBT. Materials and Methods Institutional ethics approval was obtained. Twenty-three experienced breast radiologists reviewed 50 cases in two modes, DM alone and DM+DBT. Twenty-seven cases presented with breast cancer. Each radiologist was asked to detect breast lesions and give a confidence score of 1-5 (1- Normal, 2- Benign, 3- Equivocal, 4- Suspicious, 5- Malignant). Radiologists were divided into three sub-groups according to their prior experience with DBT (none, workshop experience, and clinical experience). Confidence scores using DM+DBT were compared with DM alone for all readers combined and for each DBT experience subgroup. Statistical analyses, using GraphPad Prism 5, were carried out using the Wilcoxon signed-rank test with statistical significance set at p< 0.05. Results Confidence scores were higher for true positive cancer cases using DM+DBT compared with DM alone for all readers (p < 0.0001). Confidence scores for normal cases were lower (indicating greater confidence in the non-cancer diagnosis) with DM+DBT compared with DM alone for all readers (p= 0.018) and readers with no prior DBT experience (p= 0.035). Conclusion Addition of DBT to DM increases the confidence level of radiologists in scoring cancer and normal/benign cases. This finding appears to apply across radiologists with varying levels of DBT experience, however further work involving greater numbers of radiologists is required.

  9. Combination of conspicuity improved synthetic mammograms and digital breast tomosynthesis: a promising approach for mass detection

    NASA Astrophysics Data System (ADS)

    Kim, Seong Tae; Kim, Dae Hoe; Ro, Yong Man

    2015-03-01

    In this study, a novel mass detection framework that utilizes the information from synthetic mammograms has been developed for detecting masses in digital breast tomosynthesis (DBT). In clinical study, it is demonstrated that the combination of DBT and full field digital mammography (FFDM) increases the reader performance. To reduce the radiation dose in this approach, synthetic mammogram has been developed in previous researches and it is demonstrated that synthetic mammogram can alternate the FFDM when it is used with DBT. In this study, we investigate the feasibility of the combined approach of DBT and synthetic mammogram in point of computer-aided detection (CAD). As a synthetic mammogram, two-dimensional image was generated by adopting conspicuous voxels of three-dimensional DBT volume in our study. The mass likelihood scores estimated for each mass candidates in synthetic mammogram and DBT are merged to differentiate masses and false positives (FPs) in combined approach. We compared the performance of detecting masses in the proposed combined approach and DBT alone. A clinical data set of 196 DBT volumes was used to evaluate the different detection schemes. The combined approach achieved sensitivity of 80% and 89% with 1.16 and 2.37 FPs per DBT volume. The DBT alone approach achieved same sensitivities with 1.61 and 3.46 FPs per DBT volume. Experimental results show that statistically significant improvement (p = 0.002) is achieved in combined approach compared to DBT alone. These results imply that the information fusion of synthetic mammogram and DBT is a promising approach to detect masses in DBT.

  10. A comparative analysis of 2D and 3D CAD for calcifications in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Acciavatti, Raymond J.; Ray, Shonket; Keller, Brad M.; Maidment, Andrew D. A.; Conant, Emily F.

    2015-03-01

    Many medical centers offer digital breast tomosynthesis (DBT) and 2D digital mammography acquired under the same compression (i.e., "Combo" examination) for screening. This paper compares a conventional 2D CAD algorithm (Hologic® ImageChecker® CAD v9.4) for calcification detection against a prototype 3D algorithm (Hologic® ImageChecker® 3D Calc CAD v1.0). Due to the newness of DBT, the development of this 3D CAD algorithm is ongoing, and it is currently not FDA-approved in the United States. For this study, DBT screening cases with suspicious calcifications were identified retrospectively at the University of Pennsylvania. An expert radiologist (E.F.C.) reviewed images with both 2D and DBT CAD marks, and compared the marks to biopsy results. Control cases with one-year negative follow-up were also studied; these cases either possess clearly benign calcifications or lacked calcifications. To allow the user to alter the sensitivity for cancer detection, an operating point is assigned to each CAD mark. As expected from conventional 2D CAD, increasing the operating point in 3D CAD increases sensitivity and reduces specificity. Additionally, we showed that some cancers are occult to 2D CAD at all operating points. By contrast, 3D CAD allows for detection of some cancers that are missed on 2D CAD. We also demonstrated that some non-cancerous CAD marks in 3D are not present at analogous locations in the 2D image. Hence, there are additional marks when using both 2D and 3D CAD in combination, leading to lower specificity than with conventional 2D CAD alone.

  11. Screening Outcomes Following Implementation of Digital Breast Tomosynthesis in a General-Population Screening Program

    PubMed Central

    McCarthy, Anne Marie; Kontos, Despina; Synnestvedt, Marie; Tan, Kay See; Heitjan, Daniel F.; Schnall, Mitchell

    2014-01-01

    Background Early data on breast cancer screening utilizing digital breast tomosynthesis (DBT) combined with digital mammography (DM) have shown improvements in false-positive and false-negative screening rates compared with DM alone. However, these trials were performed at sites where conventional mammographic screening was concurrently performed, possibly leading to selection biases or with complex, multireader algorithms not reflecting general clinical practice. Our study reports the impact on screening outcomes for DBT screening implemented in an entire clinic population. Methods Recall rates, cancer detection, and positive predictive values of screening were compared for 15571 women screened with DBT and 10728 screened with DM alone prior to DBT implementation at a single breast imaging center. Generalized linear mixed-effects models were used to estimate the odds ratio (OR) for recall rate adjusted for age, race, presence of prior mammograms, breast density and reader. All statistical tests were two-sided. Results DBT screening showed a statistically significant reduction in recalls compared to DM alone. For the entire population, there were 16 fewer recalls (8.8% vs 10.4%, P <.001, adjusted OR = 0.80, 95% confidence interval [CI] = 0.74 to 0.88, P < .001) and 0.9 additional cancers detected per 1000 screened with DBT compared to DM alone. There was a statistically significant increase in PPV1 (6.2% vs 4.4%, P = .047). In women younger than age 50 years screened with DBT, there were 17 fewer recalls (12.3% vs 14.0%, P = .02) and 3.6 additional cancer detected per 1000 screened (5.7 vs 2.2 per 1000, P = .02). Conclusions Our data support the clinical implementation of DBT in breast cancer screening; however, larger prospective trials are needed to validate our findings in specific patient subgroups. PMID:25313245

  12. Feasibility study of dose reduction in digital breast tomosynthesis using non-local denoising algorithms

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    The main purpose of this work is to study the ability of denoising algorithms to reduce the radiation dose in Digital Breast Tomosynthesis (DBT) examinations. Clinical use of DBT is normally performed in "combo-mode", in which, in addition to DBT projections, a 2D mammogram is taken with the standard radiation dose. As a result, patients have been exposed to radiation doses higher than used in digital mammography. Thus, efforts to reduce the radiation dose in DBT examinations are of great interest. However, a decrease in dose leads to an increased quantum noise level, and related decrease in image quality. This work is aimed at addressing this problem by the use of denoising techniques, which could allow for dose reduction while keeping the image quality acceptable. We have studied two "state of the art" denoising techniques for filtering the quantum noise due to the reduced dose in DBT projections: Non-local Means (NLM) and Block-matching 3D (BM3D). We acquired DBT projections at different dose levels of an anthropomorphic physical breast phantom with inserted simulated microcalcifications. Then, we found the optimal filtering parameters where the denoising algorithms are capable of recovering the quality from the DBT images acquired with the standard radiation dose. Results using objective image quality assessment metrics showed that BM3D algorithm achieved better noise adjustment (mean difference in peak signal to noise ratio < 0.1dB) and less blurring (mean difference in image sharpness ~ 6%) than the NLM for the projections acquired with lower radiation doses.

  13. Digital Tomosynthesis System Geometry Analysis Using Convolution-Based Blur-and-Add (BAA) Model.

    PubMed

    Wu, Meng; Yoon, Sungwon; Solomon, Edward G; Star-Lack, Josh; Pelc, Norbert; Fahrig, Rebecca

    2016-01-01

    Digital tomosynthesis is a three-dimensional imaging technique with a lower radiation dose than computed tomography (CT). Due to the missing data in tomosynthesis systems, out-of-plane structures in the depth direction cannot be completely removed by the reconstruction algorithms. In this work, we analyzed the impulse responses of common tomosynthesis systems on a plane-to-plane basis and proposed a fast and accurate convolution-based blur-and-add (BAA) model to simulate the backprojected images. In addition, the analysis formalism describing the impulse response of out-of-plane structures can be generalized to both rotating and parallel gantries. We implemented a ray tracing forward projection and backprojection (ray-based model) algorithm and the convolution-based BAA model to simulate the shift-and-add (backproject) tomosynthesis reconstructions. The convolution-based BAA model with proper geometry distortion correction provides reasonably accurate estimates of the tomosynthesis reconstruction. A numerical comparison indicates that the simulated images using the two models differ by less than 6% in terms of the root-mean-squared error. This convolution-based BAA model can be used in efficient system geometry analysis, reconstruction algorithm design, out-of-plane artifacts suppression, and CT-tomosynthesis registration. PMID:26208308

  14. An object-oriented simulator for 3D digital breast tomosynthesis imaging system.

    PubMed

    Seyyedi, Saeed; Cengiz, Kubra; Kamasak, Mustafa; Yildirim, Isa

    2013-01-01

    Digital breast tomosynthesis (DBT) is an innovative imaging modality that provides 3D reconstructed images of breast to detect the breast cancer. Projections obtained with an X-ray source moving in a limited angle interval are used to reconstruct 3D image of breast. Several reconstruction algorithms are available for DBT imaging. Filtered back projection algorithm has traditionally been used to reconstruct images from projections. Iterative reconstruction algorithms such as algebraic reconstruction technique (ART) were later developed. Recently, compressed sensing based methods have been proposed in tomosynthesis imaging problem. We have developed an object-oriented simulator for 3D digital breast tomosynthesis (DBT) imaging system using C++ programming language. The simulator is capable of implementing different iterative and compressed sensing based reconstruction methods on 3D digital tomosynthesis data sets and phantom models. A user friendly graphical user interface (GUI) helps users to select and run the desired methods on the designed phantom models or real data sets. The simulator has been tested on a phantom study that simulates breast tomosynthesis imaging problem. Results obtained with various methods including algebraic reconstruction technique (ART) and total variation regularized reconstruction techniques (ART+TV) are presented. Reconstruction results of the methods are compared both visually and quantitatively by evaluating performances of the methods using mean structural similarity (MSSIM) values. PMID:24371468

  15. Scattering estimation from digital breast tomosynthesis guiding near infrared spectral tomographic reconstruction

    NASA Astrophysics Data System (ADS)

    Michaelsen, Kelly E.; Krishnaswamy, Venkataramanan; Pogue, Brian W.; Poplack, Steven P.; Paulsen, Keith D.

    2013-03-01

    X-ray image pixel intensity and optical scattering are compared for 11 normal subjects to assess the feasibility of using X-ray imaging as a surrogate for optical scattering in NIR spectral tomography. Digital breast tomosynthesis exams, as well as twenty single point reflectance measurements of optical breast scattering are compared for a wide variety of breast sizes and densities to determine if scattering can be accurately predicted based on x-ray attenuation. If implemented, x-ray based scattering estimation will decrease exam time and cost as well as simplify the design of a newly developed integrated near infrared spectral tomography and digital breast tomosynthesis imaging system.

  16. Triple-energy contrast enhanced digital mammography

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  17. Mammography

    MedlinePlus

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

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

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

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

  19. High resolution stationary digital breast tomosynthesis using distributed carbon nanotube x-ray source array

    SciTech Connect

    Qian Xin; Tucker, Andrew; Gidcumb, Emily; Shan Jing; Yang Guang; Calderon-Colon, Xiomara; Sultana, Shabana; Lu Jianping; Zhou, Otto; Spronk, Derrek; Sprenger, Frank; Zhang Yiheng; Kennedy, Don; Farbizio, Tom; Jing Zhenxue

    2012-04-15

    Purpose: The purpose of this study is to investigate the feasibility of increasing the system spatial resolution and scanning speed of Hologic Selenia Dimensions digital breast tomosynthesis (DBT) scanner by replacing the rotating mammography x-ray tube with a specially designed carbon nanotube (CNT) x-ray source array, which generates all the projection images needed for tomosynthesis reconstruction by electronically activating individual x-ray sources without any mechanical motion. The stationary digital breast tomosynthesis (s-DBT) design aims to (i) increase the system spatial resolution by eliminating image blurring due to x-ray tube motion and (ii) reduce the scanning time. Low spatial resolution and long scanning time are the two main technical limitations of current DBT technology. Methods: A CNT x-ray source array was designed and evaluated against a set of targeted system performance parameters. Simulations were performed to determine the maximum anode heat load at the desired focal spot size and to design the electron focusing optics. Field emission current from CNT cathode was measured for an extended period of time to determine the stable life time of CNT cathode for an expected clinical operation scenario. The source array was manufactured, tested, and integrated with a Selenia scanner. An electronic control unit was developed to interface the source array with the detection system and to scan and regulate x-ray beams. The performance of the s-DBT system was evaluated using physical phantoms. Results: The spatially distributed CNT x-ray source array comprised 31 individually addressable x-ray sources covering a 30 angular span with 1 pitch and an isotropic focal spot size of 0.6 mm at full width at half-maximum. Stable operation at 28 kV(peak) anode voltage and 38 mA tube current was demonstrated with extended lifetime and good source-to-source consistency. For the standard imaging protocol of 15 views over 14, 100 mAs dose, and 2 x 2 detector binning

  20. High resolution stationary digital breast tomosynthesis using distributed carbon nanotube x-ray source array

    PubMed Central

    Qian, Xin; Tucker, Andrew; Gidcumb, Emily; Shan, Jing; Yang, Guang; Calderon-Colon, Xiomara; Sultana, Shabana; Lu, Jianping; Zhou, Otto; Spronk, Derrek; Sprenger, Frank; Zhang, Yiheng; Kennedy, Don; Farbizio, Tom; Jing, Zhenxue

    2012-01-01

    Purpose: The purpose of this study is to investigate the feasibility of increasing the system spatial resolution and scanning speed of Hologic Selenia Dimensions digital breast tomosynthesis (DBT) scanner by replacing the rotating mammography x-ray tube with a specially designed carbon nanotube (CNT) x-ray source array, which generates all the projection images needed for tomosynthesis reconstruction by electronically activating individual x-ray sources without any mechanical motion. The stationary digital breast tomosynthesis (s-DBT) design aims to (i) increase the system spatial resolution by eliminating image blurring due to x-ray tube motion and (ii) reduce the scanning time. Low spatial resolution and long scanning time are the two main technical limitations of current DBT technology. Methods: A CNT x-ray source array was designed and evaluated against a set of targeted system performance parameters. Simulations were performed to determine the maximum anode heat load at the desired focal spot size and to design the electron focusing optics. Field emission current from CNT cathode was measured for an extended period of time to determine the stable life time of CNT cathode for an expected clinical operation scenario. The source array was manufactured, tested, and integrated with a Selenia scanner. An electronic control unit was developed to interface the source array with the detection system and to scan and regulate x-ray beams. The performance of the s-DBT system was evaluated using physical phantoms. Results: The spatially distributed CNT x-ray source array comprised 31 individually addressable x-ray sources covering a 30 angular span with 1 pitch and an isotropic focal spot size of 0.6 mm at full width at half-maximum. Stable operation at 28 kV(peak) anode voltage and 38 mA tube current was demonstrated with extended lifetime and good source-to-source consistency. For the standard imaging protocol of 15 views over 14, 100 mAs dose, and 2 × 2 detector

  1. Automatic correspondence detection in mammogram and breast tomosynthesis images

    NASA Astrophysics Data System (ADS)

    Ehrhardt, Jan; Krüger, Julia; Bischof, Arpad; Barkhausen, Jörg; Handels, Heinz

    2012-02-01

    Two-dimensional mammography is the major imaging modality in breast cancer detection. A disadvantage of mammography is the projective nature of this imaging technique. Tomosynthesis is an attractive modality with the potential to combine the high contrast and high resolution of digital mammography with the advantages of 3D imaging. In order to facilitate diagnostics and treatment in the current clinical work-flow, correspondences between tomosynthesis images and previous mammographic exams of the same women have to be determined. In this paper, we propose a method to detect correspondences in 2D mammograms and 3D tomosynthesis images automatically. In general, this 2D/3D correspondence problem is ill-posed, because a point in the 2D mammogram corresponds to a line in the 3D tomosynthesis image. The goal of our method is to detect the "most probable" 3D position in the tomosynthesis images corresponding to a selected point in the 2D mammogram. We present two alternative approaches to solve this 2D/3D correspondence problem: a 2D/3D registration method and a 2D/2D mapping between mammogram and tomosynthesis projection images with a following back projection. The advantages and limitations of both approaches are discussed and the performance of the methods is evaluated qualitatively and quantitatively using a software phantom and clinical breast image data. Although the proposed 2D/3D registration method can compensate for moderate breast deformations caused by different breast compressions, this approach is not suitable for clinical tomosynthesis data due to the limited resolution and blurring effects perpendicular to the direction of projection. The quantitative results show that the proposed 2D/2D mapping method is capable of detecting corresponding positions in mammograms and tomosynthesis images automatically for 61 out of 65 landmarks. The proposed method can facilitate diagnosis, visual inspection and comparison of 2D mammograms and 3D tomosynthesis images for

  2. Assessing and improving cobalt-60 digital tomosynthesis image quality

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  3. Visibility of single spiculations in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Timberg, Pontus; Dustler, Magnus; Förnvik, Daniel; Zackrisson, Sophia

    2013-03-01

    Purpose: To investigate the visibility of single spiculations in digital breast tomosynthesis (DBT). Method: Simulated spheres (6 mm diameter) with single spiculations were added to projection images acquired on a DBT system (MAMMOMAT Inspiration, Siemens). The spiculations had a cylindrical shape and were randomly, diagonally aligned (at four different positions: +/- π/4 or +/- 3π/4) at a plane parallel to the detector. They were assumed to consist of a fibroglandular tissue composition. The length of the spiculations was 5 mm while the diameter varied (0.12 - 0.28 mm). Reconstructed central slices of the lesion, separated by insertion in fatty or dense breasts (100 images in each), were used in 4-alternative forced choice (4AFC) human observer experiments. Three different reconstructions were used: filtered back projection (FBP) with 1 mm thick slices and a statistical artifact reduction reconstruction (SAR) method generating 1 and 2 mm thick slices. Five readers participated and their task was to locate the spiculation in randomly presented images from the whole image set (4 diameters × 100 images). The percent correct (PC) decision was determined in both fat and dense tissue for all spiculation diameters and reconstructions. Results: At a PC level of 95% the required diameter was about 0.17 - 0.22 mm in dense tissue, and 0.18 - 0.26 mm in fatty tissue (depending upon reconstruction). Conclusions: SAR was found to be a promising alternative to FBP. The visibility of single spiculations was determined. The required diameter depends on both tissue composition and reconstruction.

  4. Computerized mass detection for digital breast tomosynthesis directly from the projection images

    SciTech Connect

    Reiser, I.; Nishikawa, R.M.; Giger, M.L.; Wu, T.; Rafferty, E.A.; Moore, R.; Kopans, D.B.

    2006-02-15

    Digital breast tomosynthesis (DBT) has recently emerged as a new and promising three-dimensional modality in breast imaging. In DBT, the breast volume is reconstructed from 11 projection images, taken at source angles equally spaced over an arc of 50 degrees. Reconstruction algorithms for this modality are not fully optimized yet. Because computerized lesion detection in the reconstructed breast volume will be affected by the reconstruction technique, we are developing a novel mass detection algorithm that operates instead on the set of raw projection images. Mass detection is done in three stages. First, lesion candidates are obtained for each projection image separately, using a mass detection algorithm that was initially developed for screen-film mammography. Second, the locations of a lesion candidate are backprojected into the breast volume. In this feature volume, voxel intensities are a combined measure of detection frequency (e.g., the number of projections in which a given lesion candidate was detected), and a measure of the angular range over which a given lesion was detected. Third, features are extracted after reprojecting the three-dimensional (3-D) locations of lesion candidates into projection images. Features are combined using linear discriminant analysis. The database used to test the algorithm consisted of 21 mass cases (13 malignant, 8 benign) and 15 cases without mass lesions. Based on this database, the algorithm yielded a sensitivity of 90% at 1.5 false positives per breast volume. Algorithm performance is positively biased because this dataset was used for development, training, and testing, and because the number of algorithm parameters was approximately the same as the number of patient cases. Our results indicate that computerized mass detection in the sequence of projection images for DBT may be effective despite the higher noise level in those images.

  5. Wavelet processing techniques for digital mammography

    NASA Astrophysics Data System (ADS)

    Laine, Andrew F.; Song, Shuwu

    1992-09-01

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

  6. Toward quantification of breast tomosynthesis imaging

    NASA Astrophysics Data System (ADS)

    Shafer, Christina M.; Samei, Ehsan; Saunders, Robert S.; Zerhouni, Moustafa; Lo, Joseph Y.

    2008-03-01

    Due to the high prevalence of breast cancer among women, much is being done to detect breast cancer earlier and more accurately. In current clinical practice, the most widely-used mode of breast imaging is mammography. Its main advantages are high sensitivity and low patient dose, although it is still merely a two-dimensional projection of a three-dimensional object. In digital breast tomosynthesis, a three-dimensional image of the breast can be reconstructed, but x-ray projection images of the breast are taken over a limited angular span. However, the breast tomosynthesis device itself is more similar to a digital mammography system and thus is a feasible replacement for mammography. Because of the angular undersampling in breast tomosynthesis, the reconstructed images are not considered quantitative, so a worthwhile question to answer would be whether the voxel values (VVs) in breast tomosynthesis images can be made to indicate tissue type as Hounsfield units do in CT. through some image processing scheme. To investigate this, simple phantoms were imaged consisting of layers of uniform, tissue-equivalent plastic for the background sandwiching a layer of interest containing multiple, small cuboids of tissue-equivalent plastic. After analyzing the reconstructed tomosynthesis images, it was found that the VV in each lesion increases linearly with tissue glandularity. However, for the two different x-ray tube energies and for the two different beam exposure levels tested, the trend-lines all have different slopes and y-intercepts. Thus, breast tomosynthesis has a definite potential to be quantitative, and it would be worthwhile to study other possible dependent parameters (phantom thickness, overall density, etc.) as well as alternative reconstruction algorithms.

  7. Usefulness of Digital Tomosynthesis for the Detection of Airway Obstruction: A Case Report of Bronchial Carcinosarcoma

    PubMed Central

    Park, Sung-Joon; Choo, Ji Yung; Lee, Ki Yeol; Kim, Je-Hyeong; Choi, Jung-Woo; Yeom, Suk Keu; Kim, Baek Hyun

    2015-01-01

    Bronchial carcinosarcoma is a very rare malignant tumor that is composed of carcinomatous and sarcomatous elements. We describe the first case in which digital tomosynthesis was useful for the evaluation of airway obstruction by bronchial carcinosarcoma that was overlooked on initial chest radiography. PMID:25381829

  8. Comparison of Sonography versus Digital Breast Tomosynthesis to Locate Intramammary Marker Clips

    PubMed Central

    Schulz-Wendtland, R.; Dankerl, P.; Dilbat, G.; Bani, M.; Fasching, P. A.; Heusinger, K.; Lux, M. P.; Loehberg, C. R.; Jud, S. M.; Rauh, C.; Bayer, C. M.; Beckmann, M. W.; Wachter, D. L.; Uder, M.; Meier-Meitinger, M.; Brehm, B.

    2015-01-01

    Introduction: This study aimed to compare the accuracy of sonography versus digital breast tomosynthesis to locate intramammary marker clips placed under ultrasound guidance. Patients and Methods: Fifty patients with suspicion of breast cancer (lesion diameter less than 2 cm [cT1]) had ultrasound-guided core needle biopsy with placement of a marker clip in the center of the tumor. Intramammary marker clips were subsequently located with both sonography and digital breast tomosynthesis. Results: Sonography detected no dislocation of intrammammary marker clips in 42 of 50 patients (84 %); dislocation was reported in 8 patients (16 %) with a maximum dislocation of 7 mm along the x-, y- or z-axis. Digital breast tomosynthesis showed accurate placement without dislocation of the intramammary marker clip in 48 patients (96 %); 2 patients (4 %) had a maximum clip dislocation of 3 mm along the x-, y- or z-axis (p < 0.05). Conclusion: The use of digital breast tomosynthesis could improve the accuracy when locating intramammary marker clips compared to sonography and could, in future, be used to complement or even completely replace sonography. PMID:25684789

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

    PubMed

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

    2013-01-01

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

  10. Introductory pictorial atlas of 3D tomosynthesis.

    PubMed

    Cohen, Stuart L; Margolies, Laurie R; Szabo, Janet R; Patel, Neesha S; Hermann, George

    2014-01-01

    Mammography is an essential tool for early detection of breast cancer. Breast imaging based on three-dimensional digital breast tomosynthesis (DBT) is a new method for breast cancer screening and diagnosis that uses three-dimensional digital images to allow separation of overlapping breast structures, which may allow for improved visualization of potentially significant findings. This article will highlight the utility of DBT as a tool for the detection of breast pathology; it will demonstrate normal findings as well as breast pathology on DBT and two-dimensional conventional mammography. DBT is a very promising modality, which may decrease the false-positive rate of mammography and find additional abnormalities not seen on two-dimensional mammography. PMID:24113063

  11. Observation of super-resolution in digital breast tomosynthesis

    SciTech Connect

    Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2012-12-15

    Purpose: Digital breast tomosynthesis (DBT) is a 3D x-ray imaging modality in which tomographic sections of the breast are generated from a limited range of tube angles. Because oblique x-ray incidence shifts the image of an object in subpixel detector element increments with each increasing projection angle, it is demonstrated that DBT is capable of super-resolution (i.e., subpixel resolution). Methods: By convention, DBT reconstructions are performed on planes parallel to the breast support at various depths of the breast volume. In order for resolution in each reconstructed slice to be comparable to the detector, the pixel size should match that of the detector elements; hence, the highest frequency that can be resolved in the plane of reconstruction is the alias frequency of the detector. This study considers reconstruction grids with much smaller pixelation to visualize higher frequencies. For analytical proof of super-resolution, a theoretical framework is developed in which the reconstruction of a high frequency sinusoidal input is calculated using both simple backprojection (SBP) and filtered backprojection. To study the frequency spectrum of the reconstruction, its Fourier transform is also determined. The experimental feasibility of super-resolution was investigated by acquiring images of a bar pattern phantom with frequencies higher than the detector alias frequency. Results: Using analytical modeling, it is shown that the central projection cannot resolve frequencies exceeding the detector alias frequency. The Fourier transform of the central projection is maximized at a lower frequency than the input as evidence of aliasing. By contrast, SBP reconstruction can resolve the input, and its Fourier transform is correctly maximized at the input frequency. Incorporating filters into the reconstruction smoothens pixelation artifacts in the spatial domain and reduces spectral leakage in the Fourier domain. It is also demonstrated that the existence of super

  12. Improved digital breast tomosynthesis images using automated ultrasound

    PubMed Central

    Zhang, Xing; Yuan, Jie; Du, Sidan; Kripfgans, Oliver D.; Wang, Xueding; Carson, Paul L.; Liu, Xiaojun

    2014-01-01

    Purpose: Digital breast tomosynthesis (DBT) offers poor image quality along the depth direction. This paper presents a new method that improves the image quality of DBT considerably through the a priori information from automated ultrasound (AUS) images. Methods: DBT and AUS images of a complex breast-mimicking phantom are acquired by a DBT/AUS dual-modality system. The AUS images are taken in the same geometry as the DBT images and the gradient information of the in-slice AUS images is adopted into the new loss functional during the DBT reconstruction process. The additional data allow for new iterative equations through solving the optimization problem utilizing the gradient descent method. Both visual comparison and quantitative analysis are employed to evaluate the improvement on DBT images. Normalized line profiles of lesions are obtained to compare the edges of the DBT and AUS-corrected DBT images. Additionally, image quality metrics such as signal difference to noise ratio (SDNR) and artifact spread function (ASF) are calculated to quantify the effectiveness of the proposed method. Results: In traditional DBT image reconstructions, serious artifacts can be found along the depth direction (Z direction), resulting in the blurring of lesion edges in the off-focus planes parallel to the detector. However, by applying the proposed method, the quality of the reconstructed DBT images is greatly improved. Visually, the AUS-corrected DBT images have much clearer borders in both in-focus and off-focus planes, fewer Z direction artifacts and reduced overlapping effect compared to the conventional DBT images. Quantitatively, the corrected DBT images have better ASF, indicating a great reduction in Z direction artifacts as well as better Z resolution. The sharper line profiles along the Y direction show enhancement on the edges. Besides, noise is also reduced, evidenced by the obviously improved SDNR values. Conclusions: The proposed method provides great improvement on

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

    PubMed

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

    2016-09-01

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

  14. An experimental study of the scatter correction by using a beam-stop-array algorithm with digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Digital breast tomosynthesis (DBT) is a technique that was developed to overcome the limitations of conventional digital mammography by reconstructing slices through the breast from projections acquired at different angles. In developing and optimizing DBT, The x-ray scatter reduction technique remains a significant challenge due to projection geometry and radiation dose limitations. The most common approach to scatter reduction is a beam-stop-array (BSA) algorithm; however, this method raises concerns regarding the additional exposure involved in acquiring the scatter distribution. The compressed breast is roughly symmetric, and the scatter profiles from projections acquired at axially opposite angles are similar to mirror images. The purpose of this study was to apply the BSA algorithm with only two scans with a beam stop array, which estimates the scatter distribution with minimum additional exposure. The results of the scatter correction with angular interpolation were comparable to those of the scatter correction with all scatter distributions at each angle. The exposure increase was less than 13%. This study demonstrated the influence of the scatter correction obtained by using the BSA algorithm with minimum exposure, which indicates its potential for practical applications.

  15. Characterization of lesions in dense breasts: Does tomosynthesis help?

    PubMed Central

    Rangarajan, Krithika; Hari, Smriti; Thulkar, Sanjay; Sharma, Sanjay; Srivastava, Anurag; Parshad, Rajinder

    2016-01-01

    Context: Mammography in dense breasts is challenging due to lesion obscuration by tissue overlap. Does tomosynthesis offers a solution? Aims: To study the impact of digital breast tomosynthesis (DBT) in characterizing lesions in breasts of different mammographic densities. Settings and Design: Prospective blinded study comparing mammography in two views with Mammography + Tomosynthesis. Methods and Material: Tomosynthesis was performed in 199 patients who were assigned Breast imaging reporting and data system (BIRADS) categories 0, 3, 4, or 5 on two-dimensional (2D) mammogram. Mammograms were first categorized into one of 4 mammographic breast densities in accordance with the American College of Radiology (ACR). Three radiologists independently analyzed these images and assigned a BIRADS category first based on 2D mammogram alone, and then assigned a fresh BIRADS category after taking mammography and tomosynthesis into consideration. A composite gold-standard was used in the study (histopathology, ultrasound, follow-up mammogram, magnetic resonance imaging). Each lesion was categorized into 3 groups—superior categorization with DBT, no change in BIRADS, or inferior BIRADS category based on comparison with the gold-standard. The percentage of lesions in each group was calculated for different breast densities. Results: There were 260 lesions (ages 28–85). Overall, superior categorization was seen in 21.2% of our readings on addition of DBT to mammography. DBT was most useful in ACR Densities 3 and 4 breasts where it led to more appropriate categorization in 27 and 42% of lesions, respectively. DBT also increased diagnostic confidence in 54.5 and 63.6% of lesions in ACR Densities 3 and 4, respectively. Conclusions: In a diagnostic setting, the utility of tomosynthesis increases with increasing breast density. This helps in identifying the sub category of patients where DBT can actually change management.

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

    PubMed Central

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

    2012-01-01

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

  17. Breast Cancer Risk Estimation Using Parenchymal Texture Analysis in Digital Breast Tomosynthesis

    SciTech Connect

    Ikejimba, Lynda C.; Kontos, Despina; Maidment, Andrew D. A.

    2010-10-11

    Mammographic parenchymal texture has been shown to correlate with genetic markers of developing breast cancer. Digital breast tomosynthesis (DBT) is a novel x-ray imaging technique in which tomographic images of the breast are reconstructed from multiple source projections acquired at different angles of the x-ray tube. Compared to digital mammography (DM), DBT eliminates breast tissue overlap, offering superior parenchymal tissue visualization. We hypothesize that texture analysis in DBT could potentially provide a better assessment of parenchymal texture and ultimately result in more accurate assessment of breast cancer risk. As a first step towards validating this hypothesis, we investigated the association between DBT parenchymal texture and breast percent density (PD), a known breast cancer risk factor, and compared it to DM. Bilateral DBT and DM images from 71 women participating in a breast cancer screening trial were analyzed. Filtered-backprojection was used to reconstruct DBT tomographic planes in 1 mm increments with 0.22 mm in-plane resolution. Corresponding DM images were acquired at 0.1 mm pixel resolution. Retroareolar regions of interest (ROIs) equivalent to 2.5 cm{sup 3} were segmented from the DBT images and corresponding 2.5 cm{sup 2} ROIs were segmented from the DM images. Breast PD was mammographically estimated using the Cumulus scale. Overall, DBT texture features demonstrated a stronger correlation than DM to PD. The Pearson correlation coefficients for DBT were r = 0.40 (p<0.001) for contrast and r = -0.52 (p<0.001) for homogeneity; the corresponding DM correlations were r = 0.26 (p = 0.002) and r = -0.33 (p<0.001). Multiple linear regression of the texture features versus breast PD also demonstrated significantly stronger associations in DBT (R{sup 2} = 0.39) compared to DM (R{sup 2} = 0.33). We attribute these observations to the superior parenchymal tissue visualization in DBT. Our study is the first to perform DBT texture analysis in a

  18. Automatic segmentation of mammogram and tomosynthesis images

    NASA Astrophysics Data System (ADS)

    Sargent, Dusty; Park, Sun Young

    2016-03-01

    Breast cancer is a one of the most common forms of cancer in terms of new cases and deaths both in the United States and worldwide. However, the survival rate with breast cancer is high if it is detected and treated before it spreads to other parts of the body. The most common screening methods for breast cancer are mammography and digital tomosynthesis, which involve acquiring X-ray images of the breasts that are interpreted by radiologists. The work described in this paper is aimed at optimizing the presentation of mammography and tomosynthesis images to the radiologist, thereby improving the early detection rate of breast cancer and the resulting patient outcomes. Breast cancer tissue has greater density than normal breast tissue, and appears as dense white image regions that are asymmetrical between the breasts. These irregularities are easily seen if the breast images are aligned and viewed side-by-side. However, since the breasts are imaged separately during mammography, the images may be poorly centered and aligned relative to each other, and may not properly focus on the tissue area. Similarly, although a full three dimensional reconstruction can be created from digital tomosynthesis images, the same centering and alignment issues can occur for digital tomosynthesis. Thus, a preprocessing algorithm that aligns the breasts for easy side-by-side comparison has the potential to greatly increase the speed and accuracy of mammogram reading. Likewise, the same preprocessing can improve the results of automatic tissue classification algorithms for mammography. In this paper, we present an automated segmentation algorithm for mammogram and tomosynthesis images that aims to improve the speed and accuracy of breast cancer screening by mitigating the above mentioned problems. Our algorithm uses information in the DICOM header to facilitate preprocessing, and incorporates anatomical region segmentation and contour analysis, along with a hidden Markov model (HMM) for

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

    SciTech Connect

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

    2008-04-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

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

  1. Measurements of system sharpness for two digital breast tomosynthesis systems.

    PubMed

    Marshall, N W; Bosmans, H

    2012-11-21

    The aim of this work was to propose system sharpness parameters for digital breast tomosynthesis (DBT) systems that include the influence of focus size and focus motion for use in quality assurance protocols. X-ray focus size was measured using a multiple pinhole test object, while detector presampling modulation transfer function (MTF) was measured from projection images of a 10 cm × 10 cm, 1 mm thick steel edge, for the Siemens Inspiration and Hologic Selenia Dimensions DBT systems. The height of the edge above the table was then varied from 1 to 78 mm. The MTF expected from theory for the projection images was calculated from the measured detector MTF, focus size MTF and focus motion MTF and was compared against measured curves. Two methods were used to measure the in-plane MTF in the DBT volume: a tungsten wire of diameter 25 µm and an Al edge 0.2 mm thick, both imaged with a 15 mm thick poly(methyl methacrylate) (PMMA) plate. The in-depth point spread function (PSF) was measured using an angled tungsten wire. The full 3D MTF was estimated with a 0.5 mm diameter aluminium bead held in a 45 mm thick PMMA phantom, with the bead 15 and 65 mm above the table. Inspiration DBT projection images are saved at native detector resolution (85 µm), while the Dimensions re-bins projections to 140 µm pixels (2 × 2 binning); both systems used 2 × 2 binning of projection data before reconstruction. The 50% point for the MTF (MTF(0.50)) measured in the DBT projection images for the tube-travel direction fell as a function of height above the table from 3.60 to 0.90 mm(-1) for the Inspiration system and from 2.50 to 1.20 mm(-1) for the Dimensions unit. The maximum deviation of measured MTF(0.50) from the calculated value was 13%. MTF(0.50) measured in-plane (tube-travel direction) fell as a function of height above the table from 1.66 to 0.97 mm(-1) for the Inspiration system and from 2.21 to 1.31 mm(-1) for the Dimensions system. The full-width half-maximum for the in

  2. Measurements of system sharpness for two digital breast tomosynthesis systems

    NASA Astrophysics Data System (ADS)

    Marshall, N. W.; Bosmans, H.

    2012-11-01

    The aim of this work was to propose system sharpness parameters for digital breast tomosynthesis (DBT) systems that include the influence of focus size and focus motion for use in quality assurance protocols. X-ray focus size was measured using a multiple pinhole test object, while detector presampling modulation transfer function (MTF) was measured from projection images of a 10 cm × 10 cm, 1 mm thick steel edge, for the Siemens Inspiration and Hologic Selenia Dimensions DBT systems. The height of the edge above the table was then varied from 1 to 78 mm. The MTF expected from theory for the projection images was calculated from the measured detector MTF, focus size MTF and focus motion MTF and was compared against measured curves. Two methods were used to measure the in-plane MTF in the DBT volume: a tungsten wire of diameter 25 µm and an Al edge 0.2 mm thick, both imaged with a 15 mm thick poly(methyl methacrylate) (PMMA) plate. The in-depth point spread function (PSF) was measured using an angled tungsten wire. The full 3D MTF was estimated with a 0.5 mm diameter aluminium bead held in a 45 mm thick PMMA phantom, with the bead 15 and 65 mm above the table. Inspiration DBT projection images are saved at native detector resolution (85 µm), while the Dimensions re-bins projections to 140 µm pixels (2 × 2 binning); both systems used 2 × 2 binning of projection data before reconstruction. The 50% point for the MTF (MTF0.50) measured in the DBT projection images for the tube-travel direction fell as a function of height above the table from 3.60 to 0.90 mm-1 for the Inspiration system and from 2.50 to 1.20 mm-1 for the Dimensions unit. The maximum deviation of measured MTF0.50 from the calculated value was 13%. MTF0.50 measured in-plane (tube-travel direction) fell as a function of height above the table from 1.66 to 0.97 mm-1 for the Inspiration system and from 2.21 to 1.31 mm-1 for the Dimensions system. The full-width half-maximum for the in-depth PSF was 3

  3. Numerical solution of a nonlinear least squares problem in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Landi, G.; Loli Piccolomini, E.; Nagy, J. G.

    2015-11-01

    In digital tomosynthesis imaging, multiple projections of an object are obtained along a small range of different incident angles in order to reconstruct a pseudo-3D representation (i.e., a set of 2D slices) of the object. In this paper we describe some mathematical models for polyenergetic digital breast tomosynthesis image reconstruction that explicitly takes into account various materials composing the object and the polyenergetic nature of the x-ray beam. A polyenergetic model helps to reduce beam hardening artifacts, but the disadvantage is that it requires solving a large-scale nonlinear ill-posed inverse problem. We formulate the image reconstruction process (i.e., the method to solve the ill-posed inverse problem) in a nonlinear least squares framework, and use a Levenberg-Marquardt scheme to solve it. Some implementation details are discussed, and numerical experiments are provided to illustrate the performance of the methods.

  4. Mean glandular dose estimation using MCNPX for a digital breast tomosynthesis system with tungsten/aluminum and tungsten/aluminum+silver x-ray anode-filter combinations

    SciTech Connect

    Ma, Andy K. W.; Darambara, Dimitra G.; Stewart, Alexander; Gunn, Spencer; Bullard, Edward

    2008-12-15

    Breast cancer screening with x-ray mammography, using one or two projection images of the breast, is an indispensible tool in the early detection of breast cancer in women. Digital breast tomosynthesis (DBT) is a 3D imaging technique that promises higher sensitivity and specificity in breast cancer screening at a similar radiation dose to conventional two-view screening mammography. In DBT a 3D volume is reconstructed with anisotropic voxels from a limited number of x-ray projection images acquired over a limited angle. Although the benefit of early cancer detection through screening mammography outweighs the potential risks associated with radiation, the radiation dosage to women in terms of mean glandular dose (MGD) is carefully monitored. This work studies the MGD arising from a prototype DBT system under various parameters. Two anode/filter combinations (W/Al and W/Al+Ag) were investigated; the tube potential ranges from 20 to 50 kVp; and the breast size varied between 4 and 10 cm chest wall-to-nipple distance and between 3 and 7 cm compressed breast thickness. The dosimetric effect of breast positioning with respect to the imaging detector was also reviewed. It was found that the position of the breast can affect the MGD by as much as 5% to 13% depending on the breast size.

  5. Issues to consider before implementing digital breast tomosynthesis into a breast imaging practice.

    PubMed

    Hardesty, Lara A

    2015-03-01

    OBJECTIVE. The purpose of this article is to discuss issues surrounding the implementation of digital breast tomosynthesis (DBT) into a clinical breast imaging practice and assist radiologists, technologists, and administrators who are considering the addition of this new technology to their practices. CONCLUSION. When appropriate attention is given to image acquisition, interpretation, storage, technologist and radiologist training, patient selection, billing, radiation dose, and marketing, implementation of DBT into a breast imaging practice can be successful. PMID:25714303

  6. Identification of error making patterns in lesion detection on digital breast tomosynthesis using computer-extracted image features

    NASA Astrophysics Data System (ADS)

    Wang, Mengyu; Zhang, Jing; Grimm, Lars J.; Ghate, Sujata V.; Walsh, Ruth; Johnson, Karen S.; Lo, Joseph Y.; Mazurowski, Maciej A.

    2016-03-01

    Digital breast tomosynthesis (DBT) can improve lesion visibility by eliminating the issue of overlapping breast tissue present in mammography. However, this new modality likely requires new approaches to training. The issue of training in DBT is not well explored. We propose a computer-aided educational approach for DBT training. Our hypothesis is that the trainees' educational outcomes will improve if they are presented with cases individually selected to address their weaknesses. In this study, we focus on the question of how to select such cases. Specifically, we propose an algorithm that based on previously acquired reading data predicts which lesions will be missed by the trainee for future cases (i.e., we focus on false negative error). A logistic regression classifier was used to predict the likelihood of trainee error and computer-extracted features were used as the predictors. Reader data from 3 expert breast imagers was used to establish the ground truth and reader data from 5 radiology trainees was used to evaluate the algorithm performance with repeated holdout cross validation. Receiver operating characteristic (ROC) analysis was applied to measure the performance of the proposed individual trainee models. The preliminary experimental results for 5 trainees showed the individual trainee models were able to distinguish the lesions that would be detected from those that would be missed with the average area under the ROC curve of 0.639 (95% CI, 0.580-0.698). The proposed algorithm can be used to identify difficult cases for individual trainees.

  7. Experimental investigation for determination of optimal X-ray beam tube voltages in a newly developed digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Park, Hye-Suk; Kim, Ye-Seul; Choi, Young-Wook; Choi, JaeGu; Rhee, Yong-Chun; Kim, Hee-Joung

    2014-11-01

    Our purpose was to investigate optimal tube voltages (kVp) for a newly developed digital breast tomosynthesis (DBT) process and to determine tube current-exposure time products (mA s) for the average glandular dose (AGD), which is similar to that of the two views in conventional mammography (CM). In addition, the optimal acquisition parameters for this system were compared with those of CM. The analysis was based on the contrast-to-noise ratio (CNR) from the simulated micro-calcifications on homogeneous phantoms, and the figure of merit (FOM) was retrieved from the CNR and AGD at X-ray tube voltages ranging from 24 to 40 kVp at intervals of 2 kV. The optimal kVp increased more than 2 kV with increasing glandularity for thicker (≥50 mm) breast phantoms. The optimal kVp for DBT was found to be 4-7 kV higher than that calculated for CM with breast phantoms thicker than 50 mm. This is likely due to the greater effect of noise and dose reduction by kVp increment when using the lower dose per projection in DBT. It is important to determine optimum acquisition conditions for a maximally effective DBT system. The results of our study provide useful information to further improve DBT for high quality imaging.

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

    NASA Astrophysics Data System (ADS)

    Kato, Yuri; Fujita, Naotoshi; Kodera, Yoshie

    2009-02-01

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

  9. A dual-axis tilt acquisition geometry for digital musculoskeletal tomosynthesis.

    PubMed

    Levakhina, Yulia M; Duschka, Robert L; Vogt, Florian M; Barkhausen, Joerg; Buzug, Thorsten M

    2013-07-21

    Digital tomosynthesis (DT) is a limited angle tomographic x-ray technique. It is an attractive low-dose alternative to computed tomography (CT) in many imaging applications. However, the DT dataset is incomplete, which leads to out-of-focus artifacts and limited axial resolution. In this paper, a novel dual-axis tilt acquisition geometry is proposed and evaluated. This geometry solves some issues in tomosynthesis with the traditional scanning geometry by scanning the object with a set of perpendicular arcs. In this geometry the acquisition in the additional perpendicular direction is done using a tiltable object supporting platform. The proposed geometry allows for capturing more singularities of the Radon transform, filling the Fourier space with more data and better approximating the Tuy-Smith conditions. In order to evaluate the proposed system, several studies have been carried out. To validate the simulation setup the performance of the traditional scanning geometry has been simulated and compared to known results from the literature. It has also been shown that the possible improvement of the image quality in the traditional geometry is limited. These limitations can be partially overcome by using the proposed dual-axis tilt geometry. The novel geometry is superior and with the same number of projections better reconstructed images can be obtained. All studies have been made using a software tomosynthesis simulator. A micro-CT reconstruction of a bone has been used as a software phantom. Simultaneous algebraic reconstruction has been used to reconstruct simulated projections. As a conclusion, acquiring data outside the standard arc allows for improving performance of musculoskeletal tomosynthesis. With the proposed dual-axis acquisition geometry a performance gain is achieved without an increase in dose and major modifications to the instrumentation of existing tomosynthesis devices. PMID:23787371

  10. A dual-axis tilt acquisition geometry for digital musculoskeletal tomosynthesis

    NASA Astrophysics Data System (ADS)

    Levakhina, Yulia M.; Duschka, Robert L.; Vogt, Florian M.; Barkhausen, Joerg; Buzug, Thorsten M.

    2013-07-01

    Digital tomosynthesis (DT) is a limited angle tomographic x-ray technique. It is an attractive low-dose alternative to computed tomography (CT) in many imaging applications. However, the DT dataset is incomplete, which leads to out-of-focus artifacts and limited axial resolution. In this paper, a novel dual-axis tilt acquisition geometry is proposed and evaluated. This geometry solves some issues in tomosynthesis with the traditional scanning geometry by scanning the object with a set of perpendicular arcs. In this geometry the acquisition in the additional perpendicular direction is done using a tiltable object supporting platform. The proposed geometry allows for capturing more singularities of the Radon transform, filling the Fourier space with more data and better approximating the Tuy-Smith conditions. In order to evaluate the proposed system, several studies have been carried out. To validate the simulation setup the performance of the traditional scanning geometry has been simulated and compared to known results from the literature. It has also been shown that the possible improvement of the image quality in the traditional geometry is limited. These limitations can be partially overcome by using the proposed dual-axis tilt geometry. The novel geometry is superior and with the same number of projections better reconstructed images can be obtained. All studies have been made using a software tomosynthesis simulator. A micro-CT reconstruction of a bone has been used as a software phantom. Simultaneous algebraic reconstruction has been used to reconstruct simulated projections. As a conclusion, acquiring data outside the standard arc allows for improving performance of musculoskeletal tomosynthesis. With the proposed dual-axis acquisition geometry a performance gain is achieved without an increase in dose and major modifications to the instrumentation of existing tomosynthesis devices.

  11. kV x-ray dual digital tomosynthesis for image guided lung SBRT

    NASA Astrophysics Data System (ADS)

    Partain, Larry; Boyd, Douglas; Kim, Namho; Hernandez, Andrew; Daly, Megan; Boone, John

    2016-03-01

    Two simulated sets of digital tomosynthesis images of the lungs, each acquired at a 90 degree angle from the other, with 19 projection images used for each set and SART iterative reconstructed, gives dual tomosynthesis slice image quality approaching that of spiral CT, and with a data acquisition time that is 3% of that of cone beam CT. This fast kV acquisition, should allow near real time tracking of lung tumors in patients receiving SBRT, based on a novel TumoTrakTM multi-source X-ray tube design. Until this TumoTrakTM prototype is completed over the next year, its projected performance was simulated from the DRR images created from a spiral CT data set from a lung cancer patient. The resulting dual digital tomosynthesis reconstructed images of the lung tumor were exceptional and approached that of the gold standard Feldkamp CT reconstruction of breath hold, diagnostic, spiral, multirow, CT data. The relative dose at 46 mAs was less than 10% of what it would have been if the digital tomosynthesis had been done at the 472 mAs of the CT data set. This is for a 0.77 fps imaging rate sufficient to resolve respiratory motion in many free breathing patients during SBRT. Such image guidance could decrease the magnitudes of targeting error margins by as much as 20 mm or more in the craniocaudal direction for lower lobe lesions while markedly reducing dose to normal lung, heart and other critical structures. These initial results suggest a wide range of topics for future work.

  12. Experience with a proposed teleradiology system for digital mammography

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

    Teleradiology offers significant improvement in efficiency and effectiveness over current practices in traditional film/screen-based diagnosis. In the context of digital mammography, the increasing number of women who need to be screened for breast cancer, including those in remote rural regions, make the advantages of teleradiology especially attractive for digital mammography. At the same time, the size and resolution of digital mammograms are among the most challenging to support in a cost effective teleradiology system. This paper describes a teleradiology architecture developed for use with digital mammography by GE Corporate Research and Development in collaboration with Massachusetts General Hospital under National Cancer Institute (NCI/NIH) grant number R01 CA60246-01. Experience with a testbed prototype is described. The telemammography architecture is intended to consist of a main mammography diagnostic site serving several remote screening sites. As patient exams become available, they are forwarded by an image server to the diagnostic site over a WAN communications link. A radiologist at the diagnostic site views a patient exam as it arrives, interprets it, and then relays a report back to the technician at the remote site. A secondary future scenario consists of mobile units which forward images to a remote site, which then forwards them to the main diagnostic site. The testbed architecture is based on the Digital Imaging and Communications in Medicine (DICOM) standard, created by the American College of Radiology (ACR) and National Electrical Manufacturers Association (NEMA). A specification of vendor-independent data formats and data transfer services for digital medical images, DICOM specifies a protocol suite starting at the application layer downward, including the TCP/IP layers. The current DICOM definition does not provide an information element that is specifically tailored to mammography, so we have used the DICOM secondary capture data format

  13. Monte Carlo simulation of x-ray scatter based on patient model from digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Liu, Bob; Wu, Tao; Moore, Richard H.; Kopans, Daniel B.

    2006-03-01

    We are developing a breast specific scatter correction method for digital beast tomosynthesis (DBT). The 3D breast volume was initially reconstructed from 15 projection images acquired from a GE prototype tomosynthesis system without correction of scatter. The voxel values were mapped to the tissue compositions using various segmentation schemes. This voxelized digital breast model was entered into a Monte Carlo package simulating the prototype tomosynthesis system. One billion photons were generated from the x-ray source for each projection in the simulation and images of scattered photons were obtained. A primary only projection image was then produced by subtracting the scatter image from the corresponding original projection image which contains contributions from the both primary photons and scatter photons. The scatter free projection images were then used to reconstruct the 3D breast using the same algorithm. Compared with the uncorrected 3D image, the x-ray attenuation coefficients represented by the scatter-corrected 3D image are closer to those derived from the measurement data.

  14. Digital Breast Tomosynthesis Findings after Surgical Lipomodeling in a Breast Cancer Survivor

    PubMed Central

    Daye, Dania; Conant, Emily

    2014-01-01

    Autologous fat grafting or lipomodeling is a newly-adopted technique that is gaining increasing popularity in the treatment of contour deformities following breast conservation therapy. Here, we describe the case of a 47-year-old woman with a prior history of breast cancer treated with a lumpectomy and radiation therapy. She underwent lipomodeling not only of her treated breast but also of the contralateral breast. She presented for her annual mammogram which was performed with digital breast tomosynthesis. On imaging, a space-occupying lesion of mixed density was seen, expanding the lumpectomy site. There was also subtle distortion in the contralateral, non-treated breast. This case aims to highlight the mammographic and tomosynthesis findings seen following lipomodeling that may present diagnostic challenges in this patient population. PMID:25426245

  15. A clinical image preference study comparing digital tomosynthesis with digital radiography for pediatric spinal imaging

    NASA Astrophysics Data System (ADS)

    King, Jenna M.; Elbakri, Idris A.; Reed, Martin; Wrogemann, Jens

    2011-03-01

    The purpose of this study was to evaluate the diagnostic quality of digital tomosynthesis (DT) images for pediatric imaging of the spine. We performed a phantom image rating study to assess the visibility of anatomical spinal structures in DT images relative to digital radiography (DR) and computed tomography (CT). We collected DT and DR images of the cervical, thoracic and lumbar spine using anthropomorphic phantoms. Four pediatric radiologists and two residents rated the visibility of structures on the DT image sets compared to DR using a four point scale (0 = not visible; 1 = visible; 2 = superior to DR; 3 = excellent, CT unnecessary). In general, the structures in the spine received ratings between 1 and 3 (cervical), or 2 and 3 (thoracic, lumbar), with a few mixed scores for structures that are usually difficult to see on diagnostic images, such as vertebrae near the cervical-thoracic joint and the apophyseal joints of the lumbar spine. The DT image sets allow most critical structures to be visualized as well or better than DR. When DR imaging is inconclusive, DT is a valuable tool to consider before sending a pediatric patient for a higher-dose CT exam.

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

    PubMed Central

    2016-01-01

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

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

    PubMed

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    SciTech Connect

    Lai, C.-J.; Shaw, Chris C.; Geiser, William; Chen, Lingyun; Arribas, Elsa; Stephens, Tanya; Davis, Paul L.; Ayyar, Geetha P.; Dogan, Basak E.; Nguyen, Victoria A.; Whitman, Gary J.; Yang, Wei T.

    2008-06-15

    The purpose of this study was to evaluate and compare microcalcification detectability of two commercial full-field digital mammography (DM) systems. The first unit was a flat panel based DM system (FFDM) which employed an anti-scatter grid method to reject scatter, and the second unit was a charge-coupled device-based DM system (SSDM) which used scanning slot imaging geometry to reduce scatter radiation. Both systems have comparable scatter-to-primary ratios. In this study, 125-160 and 200-250 {mu}m calcium carbonate grains were used to simulate microcalcifications and imaged by both DM systems. The calcium carbonate grains were overlapped with a 5-cm-thick 50% adipose/50% glandular simulated breast tissue slab and an anthropomorphic breast phantom (RMI 165, Gammex) for imaging at two different mean glandular dose levels: 0.87 and 1.74 mGy. A reading study was conducted with seven board certified mammographers with images displayed on review workstations. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (A{sub z}) was used to quantify and compare the performances of these two systems. The results showed that with the simulated breast tissue slab (uniform background), the SSDM system resulted in higher A{sub z}'s than the FFDM system at both MGD levels with the difference statistically significant at 0.87 mGy only. With the anthropomorphic breast phantom (tissue structure background), the SSDM system performed better than the FFDM system at 0.87 mGy but worse at 1.74 mGy. However, the differences were not found to be statistically significant.

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

    PubMed Central

    Lai, Chao-Jen; Shaw, Chris C.; Geiser, William; Chen, Lingyun; Arribas, Elsa; Stephens, Tanya; Davis, Paul L.; Ayyar, Geetha P.; Dogan, Basak E.; Nguyen, Victoria A.; Whitman, Gary J.; Yang, Wei T.

    2008-01-01

    The purpose of this study was to evaluate and compare microcalcification detectability of two commercial full-field digital mammography (DM) systems. The first unit was a flat panel based DM system (FFDM) which employed an anti-scatter grid method to reject scatter, and the second unit was a charge-coupled device-based DM system (SSDM) which used scanning slot imaging geometry to reduce scatter radiation. Both systems have comparable scatter-to-primary ratios. In this study, 125–160 and 200–250 μm calcium carbonate grains were used to simulate microcalcifications and imaged by both DM systems. The calcium carbonate grains were overlapped with a 5-cm-thick 50% adipose∕50% glandular simulated breast tissue slab and an anthropomorphic breast phantom (RMI 165, Gammex) for imaging at two different mean glandular dose levels: 0.87 and 1.74 mGy. A reading study was conducted with seven board certified mammographers with images displayed on review workstations. A five-point confidence level rating was used to score each detection task. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (Az) was used to quantify and compare the performances of these two systems. The results showed that with the simulated breast tissue slab (uniform background), the SSDM system resulted in higher Az’s than the FFDM system at both MGD levels with the difference statistically significant at 0.87 mGy only. With the anthropomorphic breast phantom (tissue structure background), the SSDM system performed better than the FFDM system at 0.87 mGy but worse at 1.74 mGy. However, the differences were not found to be statistically significant. PMID:18649467

  1. Digital tomosynthesis-experiences with a new imaging device for the dental field.

    PubMed

    Ziegler, Christoph M; Franetzki, Manfred; Denig, Tina; Mühling, Joachim; Hassfeld, Stefan

    2003-03-01

    Based on the principles of classic film tomography, a new digital X-ray device for dental sites was developed and clinically evaluated. The tomosynthesis process produces several slices from a finite number of radiographs taken from different projection angles, obtaining a three-dimensional image of the jaws and teeth. During evaluation of an industrial prototype, a total of 52 tomosynthesis data sets were made covering different anatomic areas. Of those, 32 sets were assessed by ten radiologically experienced dentists. Anatomic regions not shown on conventional intraoral dental films were displayed due to the extraoral sensor. Diagnostic images of high value were mainly achieved within the scope of lateral views and transverse views in the frontal region. Even small structures such as the periodontal ligament could be shown in several planes, resulting in superposition-free representation. The elimination of metal artefacts caused by dental restorations was facilitated. However, improvements can be made in definition and resolution. Views in the sagittal plane and incomplete blurring of the contralateral jaw are difficulties that remain. The tomosynthesis process combined with a planned 3D representation is likely to be well suited for dental radiology. The use of such a device could be much less expensive than computed tomography (CT). Furthermore, it offers higher spatial resolution, exposes patients to less radiation, and could be easily used in daily practice, even chairside. PMID:12673437

  2. Design and evaluation of a grid reciprocation scheme for use in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Patel, Tushita; Sporkin, Helen; Peppard, Heather; Williams, Mark B.

    2016-03-01

    This work describes a methodology for efficient removal of scatter radiation during digital breast tomosynthesis (DBT). The goal of this approach is to enable grid image obscuration without a large increase in radiation dose by minimizing misalignment of the grid focal point (GFP) and x-ray focal spot (XFS) during grid reciprocation. Hardware for the motion scheme was built and tested on the dual modality breast tomosynthesis (DMT) scanner, which combines DBT and molecular breast tomosynthesis (MBT) on a single gantry. The DMT scanner uses fully isocentric rotation of tube and x-ray detector for maintaining a fixed tube-detector alignment during DBT imaging. A cellular focused copper prototype grid with 80 cm focal length, 3.85 mm height, 0.1 mm thick lamellae, and 1.1 mm hole pitch was tested. Primary transmission of the grid at 28 kV tube voltage was on average 74% with the grid stationary and aligned for maximum transmission. It fell to 72% during grid reciprocation by the proposed method. Residual grid line artifacts (GLAs) in projection views and reconstructed DBT images are characterized and methods for reducing the visibility of GLAs in the reconstructed volume through projection image flat-field correction and spatial frequency-based filtering of the DBT slices are described and evaluated. The software correction methods reduce the visibility of these artifacts in the reconstructed volume, making them imperceptible both in the reconstructed DBT images and their Fourier transforms.

  3. 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.

  4. Optimization of exposure parameters in digital tomosynthesis considering effective dose and image quality

    NASA Astrophysics Data System (ADS)

    Choi, Seungyeon; Choi, Sunghoon; Kim, Ye-seul; Lee, Haenghwa; Lee, Donghoon; Jeon, Pil-Hyun; Jang, Dong-Hyuk; Kim, Hee-Joung

    2016-03-01

    Digital tomosynthesis system (DTS), which scans an object in a limited angle, has been considered as an innovative imaging modality which can present lower patient dose than computed tomography and solve the problem of poor depth resolution in conventional digital radiography. Although it has many powerful advantages, only breast tomosynthesis system has been adopted in many hospitals. In order to reduce the patient dose while maintaining image quality, the acquisition conditions need to be studied. In this study, we analyzed effective dose and image qualities of chest phantom using commercialized universal chest digital tomosynthesis (CDT) R/F system to study the optimized exposure parameters. We set 10 different acquisition conditions including the default acquisition condition by user manual of Shimadzu (100 kVp with 0.5 mAs). The effective dose was calculated from PCXMC software version 1.5.1 by utilizing the total X-ray exposure measured by ion chamber. The image quality was evaluated by signal difference to noise ratio (SDNR) in the regions of interest (ROIs) pulmonary arteries at different axial in-plane. We analyzed a figure of merit (FOM) which considers both the effective dose and the SDNR in order to determine the optimal acquisition condition. The results indicated that the most suitable acquisition parameters among 10 conditions were condition 7 and 8 (120 kVp with 0.04 mAs and 0.1 mAs, respectively), which indicated lower effective dose while maintaining reasonable SDNRs and FOMs for three specified regions. Further studies are needed to be conducted for detailed outcomes in CDT acquisition conditions.

  5. Design and characterization of a spatially distributed multibeam field emission x-ray source for stationary digital breast tomosynthesis

    PubMed Central

    Qian, Xin; Rajaram, Ramya; Calderon-Colon, Xiomara; Yang, Guang; Phan, Tuyen; Lalush, David S.; Lu, Jianping; Zhou, Otto

    2009-01-01

    Digital breast tomosynthesis (DBT) is a limited angle computed tomography technique that can distinguish tumors from its overlying breast tissues and has potentials for detection of cancers at a smaller size and earlier stage. Current prototype DBT scanners are based on the regular full-field digital mammography systems and require partial isocentric motion of an x-ray tube over certain angular range to record the projection views. This prolongs the scanning time and, in turn, degrades the imaging quality due to motion blur. To mitigate the above limitations, the concept of a stationary DBT (s-DBT) scanner has been recently proposed based on the newly developed spatially distributed multibeam field emission x-ray (MBFEX) source technique using the carbon nanotube. The purpose of this article is to evaluate the performance of the 25-beam MBFEX source array that has been designed and fabricated for the s-DBT system. The s-DBT system records all the projection images by electronically activating the multiple x-ray beams from different viewing angles without any mechanical motion. The configuration of the MBFEX source is close to the published values from the Siemens Mammomat system. The key issues including the x-ray flux, focal spot size, spatial resolution, scanning time, beam-to-beam consistency, and reliability are evaluated using the standard procedures. In this article, the authors describe the design and performance of a distributed x-ray source array specifically designed for the s-DBT system. They evaluate the emission current, current variation, lifetime, and focal spot sizes of the source array. An emission current of up to 18 mA was obtained at 0.5×0.3 mm effective focal spot size. The experimentally measured focal spot sizes are comparable to that of a typical commercial mammography tube without motion blurring. Trade-off between the system spatial resolution, x-ray flux, and scanning time are also discussed. Projection images of a breast phantom were

  6. Design and characterization of a spatially distributed multibeam field emission x-ray source for stationary digital breast tomosynthesis

    SciTech Connect

    Qian Xin; Rajaram, Ramya; Calderon-Colon, Xiomara; Yang Guang; Phan, Tuyen; Lalush, David S.; Lu Jianping; Zhou, Otto

    2009-10-15

    Digital breast tomosynthesis (DBT) is a limited angle computed tomography technique that can distinguish tumors from its overlying breast tissues and has potentials for detection of cancers at a smaller size and earlier stage. Current prototype DBT scanners are based on the regular full-field digital mammography systems and require partial isocentric motion of an x-ray tube over certain angular range to record the projection views. This prolongs the scanning time and, in turn, degrades the imaging quality due to motion blur. To mitigate the above limitations, the concept of a stationary DBT (s-DBT) scanner has been recently proposed based on the newly developed spatially distributed multibeam field emission x-ray (MBFEX) source technique using the carbon nanotube. The purpose of this article is to evaluate the performance of the 25-beam MBFEX source array that has been designed and fabricated for the s-DBT system. The s-DBT system records all the projection images by electronically activating the multiple x-ray beams from different viewing angles without any mechanical motion. The configuration of the MBFEX source is close to the published values from the Siemens Mammomat system. The key issues including the x-ray flux, focal spot size, spatial resolution, scanning time, beam-to-beam consistency, and reliability are evaluated using the standard procedures. In this article, the authors describe the design and performance of a distributed x-ray source array specifically designed for the s-DBT system. They evaluate the emission current, current variation, lifetime, and focal spot sizes of the source array. An emission current of up to 18 mA was obtained at 0.5x0.3 mm effective focal spot size. The experimentally measured focal spot sizes are comparable to that of a typical commercial mammography tube without motion blurring. Trade-off between the system spatial resolution, x-ray flux, and scanning time are also discussed. Projection images of a breast phantom were

  7. A comparison of the performance of digital mammography systems

    SciTech Connect

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

    2007-03-15

    An objective analysis of image quality parameters was performed for six digital mammography systems. The presampled modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) for the systems were determined at different doses, for 28 kVp with a Mo/Mo or W/Al target/filter combination and 2 mm of additional aluminium filtration. The flat-panel units have higher MTF and DQE in the mid to high frequency range than standard CR systems. The highest DQE, over the whole dose range, is for the slit-scanning direct photon counting system. Dual-side read CR can overcome the inherent x-ray absorption and signal collection limitations of standard CR mammography, improving the low-frequency DQE by 40%, to the same level as full-field systems, but it does not improve the poor spatial resolution of phosphor.

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

    PubMed

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

    2007-03-01

    An objective analysis of image quality parameters was performed for six digital mammography systems. The presampled modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) for the systems were determined at different doses, for 28 kVp with a Mo/Mo or W/Al target/filter combination and 2 mm of additional aluminium filtration. The flat-panel units have higher MTF and DQE in the mid to high frequency range than standard CR systems. The highest DQE, over the whole dose range, is for the slit-scanning direct photon counting system. Dual-side read CR can overcome the inherent x-ray absorption and signal collection limitations of standard CR mammography, improving the low-frequency DQE by 40%, to the same level as full-field systems, but it does not improve the poor spatial resolution of phosphor. PMID:17441236

  9. Use of the Hotelling observer to optimize image reconstruction in digital breast tomosynthesis.

    PubMed

    Sánchez, Adrian A; Sidky, Emil Y; Pan, Xiaochuan

    2016-01-01

    We propose an implementation of the Hotelling observer that can be applied to the optimization of linear image reconstruction algorithms in digital breast tomosynthesis. The method is based on considering information within a specific region of interest, and it is applied to the optimization of algorithms for detectability of microcalcifications. Several linear algorithms are considered: simple back-projection, filtered back-projection, back-projection filtration, and [Formula: see text]-tomography. The optimized algorithms are then evaluated through the reconstruction of phantom data. The method appears robust across algorithms and parameters and leads to the generation of algorithm implementations which subjectively appear optimized for the task of interest. PMID:26702408

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

    NASA Astrophysics Data System (ADS)

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

    1992-06-01

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

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

    PubMed

    Chevalier del Rio, M

    2013-12-01

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

  12. A review of breast tomosynthesis. Part I. The image acquisition process

    PubMed Central

    Sechopoulos, Ioannis

    2013-01-01

    Mammography is a very well-established imaging modality for the early detection and diagnosis of breast cancer. However, since the introduction of digital imaging to the realm of radiology, more advanced, and especially tomographic imaging methods have been made possible. One of these methods, breast tomosynthesis, has finally been introduced to the clinic for routine everyday use, with potential to in the future replace mammography for screening for breast cancer. In this two part paper, the extensive research performed during the development of breast tomosynthesis is reviewed, with a focus on the research addressing the medical physics aspects of this imaging modality. This first paper will review the research performed on the issues relevant to the image acquisition process, including system design, optimization of geometry and technique, x-ray scatter, and radiation dose. The companion to this paper will review all other aspects of breast tomosynthesis imaging, including the reconstruction process. PMID:23298126

  13. A review of breast tomosynthesis. Part I. The image acquisition process

    SciTech Connect

    Sechopoulos, Ioannis

    2013-01-15

    Mammography is a very well-established imaging modality for the early detection and diagnosis of breast cancer. However, since the introduction of digital imaging to the realm of radiology, more advanced, and especially tomographic imaging methods have been made possible. One of these methods, breast tomosynthesis, has finally been introduced to the clinic for routine everyday use, with potential to in the future replace mammography for screening for breast cancer. In this two part paper, the extensive research performed during the development of breast tomosynthesis is reviewed, with a focus on the research addressing the medical physics aspects of this imaging modality. This first paper will review the research performed on the issues relevant to the image acquisition process, including system design, optimization of geometry and technique, x-ray scatter, and radiation dose. The companion to this paper will review all other aspects of breast tomosynthesis imaging, including the reconstruction process.

  14. A review of breast tomosynthesis. Part I. The image acquisition process.

    PubMed

    Sechopoulos, Ioannis

    2013-01-01

    Mammography is a very well-established imaging modality for the early detection and diagnosis of breast cancer. However, since the introduction of digital imaging to the realm of radiology, more advanced, and especially tomographic imaging methods have been made possible. One of these methods, breast tomosynthesis, has finally been introduced to the clinic for routine everyday use, with potential to in the future replace mammography for screening for breast cancer. In this two part paper, the extensive research performed during the development of breast tomosynthesis is reviewed, with a focus on the research addressing the medical physics aspects of this imaging modality. This first paper will review the research performed on the issues relevant to the image acquisition process, including system design, optimization of geometry and technique, x-ray scatter, and radiation dose. The companion to this paper will review all other aspects of breast tomosynthesis imaging, including the reconstruction process. PMID:23298126

  15. CCD mosaic technique for large-field digital mammography

    SciTech Connect

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

    1996-06-01

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

  16. Calibration of x-ray digital tomosynthesis system including the compensation for image distortion

    NASA Astrophysics Data System (ADS)

    Roh, Young Jun; Koh, Kuk Won; Cho, Hyungsuck; Kim, Jin-Young; Kim, Hyung C.; Byun, Jong-Eun

    1998-10-01

    X-ray laminography and DT (digital tomosynthesis) are promising technologies to form a cross-section image of 3D objects and can be a good solution for inspection interior defects of industrial products. It has been known that digital tomosynthesis method has several advantages over laminography method in that it can overcome the problems such as blurring effect or artifact. The DT system consists of a scanning x-ray tube, an image intensifier as an x-ray image detector, and a CCD camera. To acquire an x-ray image of an arbitrary plane of objects, a set of images (8 images or more) should be synthesized by averaging or minimally calculating point by point. The images, however are distorted according to the configurations of the image intensifier and the x-ray source position. To get a clear and accurate synthesized image, the corresponding points in the distorted images should be accurately determined, and therefore, precise calibration of the DT system is needed to map the corresponding points correctly. In this work, a series of calibration methods for the DT system are presented including the correction of the center offset between the x-ray and the image intensifer, the x-ray steering calibration, and the correction of the distortion of the image. The calibration models are implemented to the DT system and the experiment results are presented and discussed in detail.

  17. Evaluation of back projection methods for breast tomosynthesis image reconstruction.

    PubMed

    Zhou, Weihua; Lu, Jianping; Zhou, Otto; Chen, Ying

    2015-06-01

    Breast cancer is the most common cancer among women in the USA. Compared to mammography, digital breast tomosynthesis is a new imaging technique that may improve the diagnostic accuracy by removing the ambiguities of overlapped tissues and providing 3D information of the breast. Tomosynthesis reconstruction algorithms generate 3D reconstructed slices from a few limited angle projection images. Among different reconstruction algorithms, back projection (BP) is considered an important foundation of quite a few reconstruction techniques with deblurring algorithms such as filtered back projection. In this paper, two BP variants, including α-trimmed BP and principal component analysis-based BP, were proposed to improve the image quality against that of traditional BP. Computer simulations and phantom studies demonstrated that the α-trimmed BP may improve signal response performance and suppress noise in breast tomosynthesis image reconstruction. PMID:25384538

  18. Initial application of digital tomosynthesis with on-board imaging in radiation oncology

    NASA Astrophysics Data System (ADS)

    Baydush, Alan H.; Godfrey, Devon J.; Oldham, Mark; Dobbins, James T., III

    2005-04-01

    We present preliminary investigations that examine the feasibility of incorporating digital tomosynthesis into radiation oncology practice with the use of kilovoltage on-board imagers (OBI). Modern radiation oncology linear accelerators now include hardware options for the addition of OBI for on-line patient setup verification. These systems include an x-ray tube and detector mounted directly on the accelerator gantry that rotate with the same isocenter. Applications include cone beam computed tomography (CBCT), fluoroscopy, and radiographs to examine daily patient positioning to determine if the patient is in the same location as the treatment plan. While CBCT provides the greatest anatomical detail, this approach is limited by long acquisition and reconstruction times and higher patient dose. We propose to examine the use of tomosynthesis reconstructed volumetric data from limited angle projection images for short imaging time and reduced patient dose. Initial data uses 61 projection images acquired over an isocentric arc of twenty degrees with the detector approximately fifty-four centimeters from isocenter. A modified filtered back projection technique, which included a mathematical correction for isocentric motion, was used to reconstruct volume images. These images will be visually and mathematically compared to volumetric computed tomography images to determine efficacy of this system for daily patient positioning verification. Initial images using the tomosynthesis reconstruction technique show much promise and bode well for effective daily patient positioning verification with reduced patient dose and imaging time. Additionally, the fast image acquisition may allow for a single breath hold imaging sequence, which will have no breath motion.

  19. Mammography

    PubMed Central

    Samuels, Taube H.

    1992-01-01

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

  20. Parallel hardware architecture for CCD-mosaic digital mammography

    NASA Astrophysics Data System (ADS)

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

    1998-06-01

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

  1. Dosimetric characterization and organ dose assessment in digital breast tomosynthesis: Measurements and Monte Carlo simulations using voxel phantoms

    SciTech Connect

    Baptista, Mariana Di Maria, Salvatore; Barros, Sílvia; Vaz, Pedro; Figueira, Catarina; Sarmento, Marta; Orvalho, Lurdes

    2015-07-15

    Purpose: Due to its capability to more accurately detect deep lesions inside the breast by removing the effect of overlying anatomy, digital breast tomosynthesis (DBT) has the potential to replace the standard mammography technique in clinical screening exams. However, the European Guidelines for DBT dosimetry are still a work in progress and there are little data available on organ doses other than to the breast. It is, therefore, of great importance to assess the dosimetric performance of DBT with respect to the one obtained with standard digital mammography (DM) systems. The aim of this work is twofold: (i) to study the dosimetric properties of a combined DBT/DM system (MAMMOMAT Inspiration Siemens{sup ®}) for a tungsten/rhodium (W/Rh) anode/filter combination and (ii) to evaluate organs doses during a DBT examination. Methods: For the first task, measurements were performed in manual and automatic exposure control (AEC) modes, using two homogeneous breast phantoms: a PMMA slab phantom and a 4 cm thick breast-shaped rigid phantom, with 50% of glandular tissue in its composition. Monte Carlo (MC) simulations were performed using Monte Carlo N-Particle eXtended v.2.7.0. A MC model was implemented to mimic DM and DBT acquisitions for a wide range of x-ray spectra (24 –34 kV). This was used to calculate mean glandular dose (MGD) and to compute series of backscatter factors (BSFs) that could be inserted into the DBT dosimetric formalism proposed by Dance et al. Regarding the second aim of the study, the implemented MC model of the clinical equipment, together with a female voxel phantom (“Laura”), was used to calculate organ doses considering a typical DBT acquisition. Results were compared with a standard two-view mammography craniocaudal (CC) acquisition. Results: Considering the AEC mode, the acquisition of a single CC view results in a MGD ranging from 0.53 ± 0.07 mGy to 2.41 ± 0.31 mGy in DM mode and from 0.77 ± 0.11 mGy to 2.28 ± 0.32 mGy in DBT mode

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

    PubMed

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

    2008-02-01

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

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

    SciTech Connect

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

    2008-02-15

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

  4. SU-E-J-56: Static Gantry Digital Tomosynthesis From the Beam’s-Eye-View

    SciTech Connect

    Partain, L; Kwon, J; Boyd, D; Rottmann, J; Berbeco, R; Zentai, G

    2015-06-15

    Purpose We have designed a novel TumoTrak™ x-ray system that delivers 19 distinct kV views with the linac gantry stationary. It images MV treatment beam above and below the patient with a kV tomosysthesis slice image from the therapy beam’s-eye-view. Results will be high quality images without MLC shadowing for notable improvements relative to conventional fluoroscopic MV imaging and fluoroscopic kV imaging. Methods A complete design has a kV electron beam multisource X-ray tube that fits around the MV treatment beam path, with little interference with normal radiotherapy and unblocked by the multi-leaf-collimator. To simulate digital tomosynthesis, we used cone-beam CT projection data from a lung SBRT patient. These data were acquired at 125 kVp and 11 fps (0.4 mAs per projection). We chose 19 projections evenly spaced over 27° around one of the treatment angles (240°). Digital tomosynthesis reconstruction of a slice through the tumor was performed using iterative reconstruction. The visibility of the lesion was assessed for the reconstructed digital tomosynthesis (DTS), using fluoroscopy MV images acquired during radiation therapy, and a kV single projection image acquired at the same angle as the treatment field (240°). Results The fluoroscopic DTS images provide the best tumor contrast, surpassing the conventional radiographic and the in-treatment MV portal images. The electron beam multisource X-ray tube design has been completed and the tube is being fabricated. The estimated time to cycle through all 19 projections is 700 ms, enabling high frame-rate imaging. While the initial proposed use case is for image guided and gated treatment delivery, the enhanced imaging will also deliver superior radiographic images for patient setup. Conclusion The proposed device will deliver high quality planar images from the beam’s-eye-view without MLC obstruction. The prototype has been designed and is being assembled with first imaging scheduled for May 2015. L

  5. 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

  6. Computer-aided detection system for clustered microcalcifications in digital breast tomosynthesis using joint information from volumetric and planar projection images

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    We propose a novel approach for the detection of microcalcification clusters (MCs) using joint information from digital breast tomosynthesis (DBT) volume and planar projection (PPJ) image. A data set of 307 DBT views was collected with IRB approval using a prototype DBT system. The system acquires 21 projection views (PVs) from a wide tomographic angle of 60° (60°-21PV) at about twice the dose of a digital mammography (DM) system, which allows us the flexibility of simulating other DBT acquisition geometries using a subset of the PVs. In this study, we simulated a 30° DBT geometry using the central 11 PVs (30°-11PV). The narrower tomographic angle is closer to DBT geometries commercially available or under development and the dose is matched approximately to that of a DM. We developed a new joint-CAD system for detection of clustered microcalcifications. The DBT volume was reconstructed with a multiscale bilateral filtering regularized method and a PPJ image was generated from the reconstructed volume. Task-specific detection strategies were designed to combine information from the DBT volume and the PPJ image. The data set was divided into a training set (127 views with MCs) and an independent test set (104 views with MCs and 76 views without MCs). The joint-CAD system outperformed the individual CAD systems for DBT volume or PPJ image alone; the differences in the test performances were statistically significant (p  <  0.05) using JAFROC analysis.

  7. The Utility of Digital Linear Tomosynthesis Imaging of Total Hip Joint Arthroplasty with Suspicion of Loosening: A Prospective Study in 40 Patients

    PubMed Central

    Göthlin, Jan H.

    2013-01-01

    Aim. The clinical utility of digital linear tomosynthesis in musculoskeletal applications has been validated in only a few reports. Technical performance and utility in hip prosthesis imaging have been discussed in technical reports, but no clinical evaluation has been reported. The purpose of the current study was to assess the added clinical utility of digital linear tomosynthesis compared to radiography in loosening of total hip joint arthroplasty. Materials and Methods. In a prospective study, radiography and digital tomosynthesis were performed in 40 consecutive patients with total hip arthroplasty referred for suspect prosthesis loosening. Tomosynthesis images were compared to anterior-posterior (AP) and cross-table lateral radiographs regarding demarcation and extent of demineralization and osteolysis. Further noted were skeletal fractures, cement fractures, fragmentation, and artifacts interfering with the diagnosis. Results. Tomosynthesis was superior to radiography with sharper delineation of demineralization and osteolysis in the AP projection. A limitation was the inability to generate lateral tomosynthesis images, with inferior assessment of the area anterior and posterior to the acetabular cup compared to cross-table radiographs. Artifacts interfering with diagnosis were found in one hip. Conclusion. Tomosynthesis improved evaluation of total hip arthroplasty in the AP projection but was limited by the lack of lateral projections. PMID:24078921

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

    SciTech Connect

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

    2006-03-15

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

  9. OVERVIEW OF A DIGITAL TOMOSYNTHESIS DEVELOPMENT: NEW APPROACHES FOR LOW-DOSE CHEST IMAGING.

    PubMed

    Horváth, Ákos; Wolf, Péter; Nagy, János; Kelemen, Attila; Horváth, Gábor; Hadházi, Dániel; Horváth, Áron; Czétényi, Benjámin; Süttő, Zoltán; Szondy, Klára

    2016-06-01

    Lung cancer has the highest mortality rate among all cancer types, and it has especially high occurrence in Hungary. Low-dose computed tomography (LDCT) has been proved to be a beneficial screening method for lung cancer, decreasing the mortality rate by 20 %. Because of the intensifying fears from X-ray radiation, there is a need to develop other modalities that might work with less radiation and have similar sensitivity in lung nodule finding. Digital tomosynthesis (DTS) may be such a modality that can be a real alternative to LDCT. The goal of this article is to summarise the first results of a Hungarian project for developing a DTS system extended with a computer-aided detection system. It describes the main approaches applied and the main benefits of using DTS based on the first clinical examinations. PMID:26564865

  10. Calibration and optimization of 3D digital breast tomosynthesis guided near infrared spectral tomography

    PubMed Central

    Michaelsen, Kelly E.; Krishnaswamy, Venkataramanan; Shi, Linxi; Vedantham, Srinivasan; Poplack, Steven P.; Karellas, Andrew; Pogue, Brian W.; Paulsen, Keith D.

    2015-01-01

    Calibration of a three-dimensional multimodal digital breast tomosynthesis (DBT) x-ray and non-fiber based near infrared spectral tomography (NIRST) system is challenging but essential for clinical studies. Phantom imaging results yielded linear contrast recovery of total hemoglobin (HbT) concentration for cylindrical inclusions of 15 mm, 10 mm and 7 mm with a 3.5% decrease in the HbT estimate for each 1 cm increase in inclusion depth. A clinical exam of a patient’s breast containing both benign and malignant lesions was successfully imaged, with greater HbT was found in the malignancy relative to the benign abnormality and fibroglandular regions (11 μM vs. 9.5 μM). Tools developed improved imaging system characterization and optimization of signal quality, which will ultimately improve patient selection and subsequent clinical trial results. PMID:26713210

  11. Calibration and optimization of 3D digital breast tomosynthesis guided near infrared spectral tomography.

    PubMed

    Michaelsen, Kelly E; Krishnaswamy, Venkataramanan; Shi, Linxi; Vedantham, Srinivasan; Poplack, Steven P; Karellas, Andrew; Pogue, Brian W; Paulsen, Keith D

    2015-12-01

    Calibration of a three-dimensional multimodal digital breast tomosynthesis (DBT) x-ray and non-fiber based near infrared spectral tomography (NIRST) system is challenging but essential for clinical studies. Phantom imaging results yielded linear contrast recovery of total hemoglobin (HbT) concentration for cylindrical inclusions of 15 mm, 10 mm and 7 mm with a 3.5% decrease in the HbT estimate for each 1 cm increase in inclusion depth. A clinical exam of a patient's breast containing both benign and malignant lesions was successfully imaged, with greater HbT was found in the malignancy relative to the benign abnormality and fibroglandular regions (11 μM vs. 9.5 μM). Tools developed improved imaging system characterization and optimization of signal quality, which will ultimately improve patient selection and subsequent clinical trial results. PMID:26713210

  12. A second pass correction method for calcification artifacts in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Erhard, Klaus; Grass, Michael; Nielsen, Tim

    2011-03-01

    Digital breast tomosynthesis (DBT) allows a quasi-3D reconstruction of the breast with high in-plane and poor depth resolution by the principles of limited angle tomography. The limited angular range and the coarse angular sampling result in prominent streak artifacts arising from high-contrast structures such as calcifications. These artifacts do not only degrade the image quality but also hold the risk of overlaying suspicious tissue structure in neighbouring slices, which might therefore be overlooked. This work presents a second pass method for correcting these kinds of high-contrast streak artifacts. In a first pass reconstruction the candidate highcontrast calcifications are segmented and subtracted from the original projection data to generate a subsequent artifact-free second pass reconstruction. The method is demonstrated in a simulation study using software breast phantoms, which have been derived from segmented MRI data.

  13. IMAGE FUSION OF RECONSTRUCTED DIGITAL TOMOSYNTHESIS VOLUMES FROM A FRONTAL AND A LATERAL ACQUISITION.

    PubMed

    Arvidsson, Jonathan; Söderman, Christina; Allansdotter Johnsson, Åse; Bernhardt, Peter; Starck, Göran; Kahl, Fredrik; Båth, Magnus

    2016-06-01

    Digital tomosynthesis (DTS) has been used in chest imaging as a low radiation dose alternative to computed tomography (CT). Traditional DTS shows limitations in the spatial resolution in the out-of-plane dimension. As a first indication of whether a dual-plane dual-view (DPDV) DTS data acquisition can yield a fair resolution in all three spatial dimensions, a manual registration between a frontal and a lateral image volume was performed. An anthropomorphic chest phantom was scanned frontally and laterally using a linear DTS acquisition, at 120 kVp. The reconstructed image volumes were resampled and manually co-registered. Expert radiologist delineations of the mediastinal soft tissues enabled calculation of similarity metrics in regard to delineations in a reference CT volume. The fused volume produced the highest total overlap, implying that the fused volume was a more isotropic 3D representation of the examined object than the traditional chest DTS volumes. PMID:26683464

  14. Effects of angular range on image quality of chest digital tomosynthesis

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Chest digital tomosynthesis (CDT) is a new 3D imaging technique that can be expected to improve clinical diagnosis over conventional chest radiography. We investigated the effect of the angular range of data acquisition on the image quality using newly developed CDT system. The four different acquisition sets were studied using +/-15°, +/-20°, +/-30°, and +/-35° angular ranges with 21 projection views (PVs). The point spread function (PSF), modulation transfer function (MTF), artifact spread function (ASF), and normalized contrast-to-noise ratio (CNR) were used to evaluate the image quality. We found that increasing angular ranges improved vertical resolution. The results indicated that there was the opposite relationship of the CNR with angular range for the two tissue types. While CNR for heart tissue increased with increasing angular range, CNR for spine bone decreased. The results showed that the angular range is an important parameter for the CDT exam.

  15. Improving depth resolution in digital breast tomosynthesis by iterative image reconstruction

    NASA Astrophysics Data System (ADS)

    Roth, Erin G.; Kraemer, David N.; Sidky, Emil Y.; Reiser, Ingrid S.; Pan, Xiaochuan

    2015-03-01

    Digital breast tomosynthesis (DBT) is currently enjoying tremendous growth in its application to screening for breast cancer. This is because it addresses a major weakness of mammographic projection imaging; namely, a cancer can be hidden by overlapping fibroglandular tissue structures or the same normal structures can mimic a malignant mass. DBT addresses these issues by acquiring few projections over a limited angle scanning arc that provides some depth resolution. As DBT is a relatively new device, there is potential to improve its performance significantly with improved image reconstruction algorithms. Previously, we reported a variation of adaptive steepest descent - projection onto convex sets (ASD-POCS) for DBT, which employed a finite differencing filter to enhance edges for improving visibility of tissue structures and to allow for volume-of-interest reconstruction. In the present work we present a singular value decomposition (SVD) analysis to demonstrate the gain in depth resolution for DBT afforded by use of the finite differencing filter.

  16. Digital breast tomosynthesis reconstruction using spatially weighted non-convex regularization

    NASA Astrophysics Data System (ADS)

    Zheng, Jiabei; Fessler, Jeffrey A.; Chan, Heang-Ping

    2016-03-01

    Regularization is an effective strategy for reducing noise in tomographic reconstruction. This paper proposes a spatially weighted non-convex (SWNC) regularization method for digital breast tomosynthesis (DBT) image reconstruction. With a non-convex cost function, this method can suppress noise without blurring microcalcifications (MC) and spiculations of masses. To minimize the non-convex cost function, we apply a majorize-minimize separable quadratic surrogate algorithm (MM-SQS) that is further accelerated by ordered subsets (OS). We applied the new method to a heterogeneous breast phantom and to human subject DBT data, and observed improved image quality in both situations. A quantitative study also showed that the SWNC method can significantly enhance the contrast-to-noise ratio of MCs. By properly selecting its parameters, the SWNC regularizer can preserve the appearance of the mass margins and breast parenchyma.

  17. Comparison of algorithms for out-of-plane artifacts removal in digital tomosynthesis reconstructions.

    PubMed

    Bliznakova, K; Bliznakov, Z; Buliev, I

    2012-07-01

    Digital tomosynthesis is a method of limited angle reconstruction of tomographic images produced at variable heights, on the basis of a set of angular projections taken in an arc around human anatomy. Reconstructed tomograms from unprocessed original projection images, however, are invariably affected by tomographic noise such as blurred images of objects lying outside the plane of interest and superimposed on the focused image of the fulcrum plane. The present work investigates the performance of two approaches for generation of tomograms with a reduced noise: a generalised post-processing method, based on constructing a noise mask from all planes in the reconstructed volume, and its subsequent subtraction from the in-focus plane and a filtered Multiple Projection Algorithm. The comparison between the two algorithms shows that the first method provides reconstructions with very good quality in case of high contrast features, especially for those embedded into a heterogeneous background. PMID:22056810

  18. 3D digital breast tomosynthesis image reconstruction using anisotropic total variation minimization.

    PubMed

    Seyyedi, Saeed; Yildirim, Isa

    2014-01-01

    This paper presents a compressed sensing based reconstruction method for 3D digital breast tomosynthesis (DBT) imaging. Algebraic reconstruction technique (ART) has been in use in DBT imaging by minimizing the isotropic total variation (TV) of the reconstructed image. The resolution in DBT differs in sagittal and axial directions which should be encountered during the TV minimization. In this study we develop a 3D anisotropic TV (ATV) minimization by considering the different resolutions in different directions. A customized 3D Shepp-logan phantom was generated to mimic a real DBT image by considering the overlapping tissue and directional resolution issues. Results of the ART, ART+3D TV and ART+3D ATV are compared using structural similarity (SSIM) diagram. PMID:25571377

  19. 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

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

    SciTech Connect

    Isa, Norriza Mohd; Wan Hassan, Wan Muhamad Saridan

    2010-01-05

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

  1. Optimization of exposure parameters in full field digital mammography

    SciTech Connect

    Williams, Mark B.; Raghunathan, Priya; More, Mitali J.; Seibert, J. Anthony; Kwan, Alexander; Lo, Joseph Y.; Samei, Ehsan; Ranger, Nicole T.; Fajardo, Laurie L.; McGruder, Allen; McGruder, Sandra M.; Maidment, Andrew D. A.; Yaffe, Martin J.; Bloomquist, Aili; Mawdsley, Gordon E.

    2008-06-15

    Optimization of exposure parameters (target, filter, and kVp) in digital mammography necessitates maximization of the image signal-to-noise ratio (SNR), while simultaneously minimizing patient dose. The goal of this study is to compare, for each of the major commercially available full field digital mammography (FFDM) systems, the impact of the selection of technique factors on image SNR and radiation dose for a range of breast thickness and tissue types. This phantom study is an update of a previous investigation and includes measurements on recent versions of two of the FFDM systems discussed in that article, as well as on three FFDM systems not available at that time. The five commercial FFDM systems tested, the Senographe 2000D from GE Healthcare, the Mammomat Novation DR from Siemens, the Selenia from Hologic, the Fischer Senoscan, and Fuji's 5000MA used with a Lorad M-IV mammography unit, are located at five different university test sites. Performance was assessed using all available x-ray target and filter combinations and nine different phantom types (three compressed thicknesses and three tissue composition types). Each phantom type was also imaged using the automatic exposure control (AEC) of each system to identify the exposure parameters used under automated image acquisition. The figure of merit (FOM) used to compare technique factors is the ratio of the square of the image SNR to the mean glandular dose. The results show that, for a given target/filter combination, in general FOM is a slowly changing function of kVp, with stronger dependence on the choice of target/filter combination. In all cases the FOM was a decreasing function of kVp at the top of the available range of kVp settings, indicating that higher tube voltages would produce no further performance improvement. For a given phantom type, the exposure parameter set resulting in the highest FOM value was system specific, depending on both the set of available target/filter combinations, and

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

    PubMed Central

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

    2016-01-01

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

  3. Dose reduction in digital breast tomosynthesis using a penalized maximum likelihood reconstruction

    NASA Astrophysics Data System (ADS)

    Das, Mini; Gifford, Howard; O'Connor, Michael; Glick, Stephen J.

    2009-02-01

    Digital breast tomosynthesis (DBT) is a 3D imaging modality with limited angle projection data. The ability of tomosynthesis systems to accurately detect smaller microcalcifications is debatable. This is because of the higher noise in the projection data (lower average dose per projection), which is then propagated through the reconstructed image . Reconstruction methods that minimize the propagation of quantum noise have potential to improve microcalcification detectability using DBT. In this paper we show that penalized maximum likelihood (PML) reconstruction in DBT yields images with an improved resolution/noise tradeoff as compared to conventional filtered backprojection (FBP). Signal to noise ratio (SNR) using PML was observed to be higher than that obtained using the standard FBP algorithm. Our results indicate that for microcalcifications, using the PML algorithm, reconstructions obtained with a mean glandular dose (MGD) of 1.5 mGy yielded better SNR than that those obtained with FBP using a 4mGy total dose. Thus perhaps total dose could be reduced to one-third or lower with same microcalcification detectability, if PML reconstruction is used instead of FBP. Visibility of low contrast masses with various contrast levels were studied using a contrast-detail phantom in a breast shape structure with an average breast density. Images generated using various dose levels indicate that visibility of low contrast masses generated using PML reconstructions are significantly better than those generated using FBP. SNR measurements in the low-contrast study did not appear to correlate with the visual subjective analysis of the reconstruction indicating that SNR is not a good figure of merit to be used.

  4. A feasibility study for anatomical noise reduction in dual-energy chest digital tomosynthesis

    NASA Astrophysics Data System (ADS)

    Lee, D.; Kim, Y.-s.; Choi, S.; Lee, H.; Choi, S.; Kim, H.-J.

    2016-01-01

    Lung cancer is the leading cause of cancer death worldwide. Thus, early diagnosis is of considerable importance. For early screening of lung cancer, computed tomography (CT) has been used as the gold standard. Chest digital tomosynthesis (CDT) is a recently introduced modality for lung cancer screening with a relatively low radiation dose compared to CT. The dual energy material decomposition method has been proposed for better detection of pulmonary nodules by means of reducing anatomical noise. In this study, the possibility of material decomposition in CDT was tested by both a simulation study and an experimental study using a CDT prototype. The Geant4 application for tomographic emission (GATE) v6 and tungsten anode spectral model using interpolating polynomials (TASMIP) codes were used for the simulation study to create simulated phantom shapes consisting of five inner cylinders filled with different densities of bone and airequivalent materials. Furthermore, the CDT prototype system and human phantom chest were used for the experimental study. CDT scan in both the simulation and experimental studies was performed with linear movement and 21 projection images were obtained over a 30 degree angular range with a 1.5 degree angular interval. To obtain materialselective images, a projectionbased energy subtraction technique was applied to high and low energy images. The resultant simulation images showed that dual-energy reconstruction could achieve an approximately 32% higher contrast to noise ratio (CNR) in images and the difference in CNR value according to bone density was significant compared to single energy CDT. Additionally, image artifacts were effectively corrected in dual energy CDT simulation studies. Likewise the experimental study with dual energy produced clear images of lung fields and bone structure by removing unnecessary anatomical structures. Dual energy tomosynthesis is a new technique; therefore, there is little guidance regarding its

  5. Applying a 2D based CAD scheme for detecting micro-calcification clusters using digital breast tomosynthesis images: an assessment

    NASA Astrophysics Data System (ADS)

    Park, Sang Cheol; Zheng, Bin; Wang, Xiao-Hui; Gur, David

    2008-03-01

    Digital breast tomosynthesis (DBT) has emerged as a promising imaging modality for screening mammography. However, visually detecting micro-calcification clusters depicted on DBT images is a difficult task. Computer-aided detection (CAD) schemes for detecting micro-calcification clusters depicted on mammograms can achieve high performance and the use of CAD results can assist radiologists in detecting subtle micro-calcification clusters. In this study, we compared the performance of an available 2D based CAD scheme with one that includes a new grouping and scoring method when applied to both projection and reconstructed DBT images. We selected a dataset involving 96 DBT examinations acquired on 45 women. Each DBT image set included 11 low dose projection images and a varying number of reconstructed image slices ranging from 18 to 87. In this dataset 20 true-positive micro-calcification clusters were visually detected on the projection images and 40 were visually detected on the reconstructed images, respectively. We first applied the CAD scheme that was previously developed in our laboratory to the DBT dataset. We then tested a new grouping method that defines an independent cluster by grouping the same cluster detected on different projection or reconstructed images. We then compared four scoring methods to assess the CAD performance. The maximum sensitivity level observed for the different grouping and scoring methods were 70% and 88% for the projection and reconstructed images with a maximum false-positive rate of 4.0 and 15.9 per examination, respectively. This preliminary study demonstrates that (1) among the maximum, the minimum or the average CAD generated scores, using the maximum score of the grouped cluster regions achieved the highest performance level, (2) the histogram based scoring method is reasonably effective in reducing false-positive detections on the projection images but the overall CAD sensitivity is lower due to lower signal-to-noise ratio

  6. 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.

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

    PubMed

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  9. Physical characteristics of five clinical systems for digital mammography

    SciTech Connect

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

    2007-07-15

    The purpose of this study was to evaluate and compare the physical characteristics of five clinical systems for digital mammography (GE Senographe 2000D, Lorad Selenia M-IV, Fischer Senoscan, Agfa DM 1000, and IMS Giotto) currently in clinical use. The basic performances of the mammography systems tested were assessed on the basis of response curve, modulation transfer function (MTF), noise power spectrum, noise equivalent quanta (NEQ), and detective quantum efficiency (DQE) in an experimental setting closely resembling the clinical one. As expected, all the full field digital mammography systems show a linear response curve over a dynamic range from 3.5 to 500 {mu}Gy (0.998digital system, the presampling MTF was calculated within a range up to the Nyquist frequency (5 lp/mm for GE Senographe 2000D, 7.1 lp/mm for Lorad Selenia, 9.3 lp/mm for Fischer Senoscan, and 5.88 lp/mm for IMS Giotto detector). The NEQ becomes related to the exposure in a linear behavior starting from about 40.3 {mu}Gy for GE Senographe 2000D, 42.9 {mu}Gy for Lorad Selenia, 41.2 {mu}Gy for Agfa DM1000, <87.6 {mu}Gy for Fischer Senoscan, and 61.3 {mu}Gy for the IMS Giotto. Above those values, the systems can be considered ''quantum noise limited,'' that is the electronic noise is negligible if compared to the quantum noise. The DQE, for several emitted x-ray spectra for each system, i.e., 28 kV p Mo-Mo, Mo-Rh, Rh-Rh, W-Al anode-filter combination, hardened by 40 mm poly(methylmethacrylate) (PMMA) was evaluated. For the five different systems, the DQE at close to zero spatial frequency ranges between 0.25 and 0.63 at 131 {mu}Gy entrance surface air kerma to the detectors. The results of

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

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

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

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

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  13. 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,...

  14. 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,...

  15. Digital tomosynthesis for verifying spine position during radiotherapy: a phantom study

    NASA Astrophysics Data System (ADS)

    Gurney-Champion, Oliver J.; Dahele, Max; Mostafavi, Hassan; Slotman, Ben J.; Verbakel, Wilko F. A. R.

    2013-08-01

    Monitoring the stability of patient position is essential during high-precision radiotherapy such as spine stereotactic body radiotherapy (SBRT). We evaluated the combination of digital tomosynthesis (DTS) and triangulation for spine position detection, using non-clinical DTS software and an anthropomorphic pelvic phantom that includes a bone-like spine structure. Kilovoltage cone beam CT projection images over 2-16° gantry rotation were used to generate single slice DTS images. Each DTS slice was registered to a digitally reconstructed DTS derived from the planning CT scan to determine 2D shifts between actual phantom and treatment plan position. Two or more DTS registrations, central axes 4-22° apart, were triangulated to determine the 3D phantom position. Using sequentially generated DTS images, the phantom position can be updated every degree with a small latency of DTS and triangulation angle. The precision of position determination was investigated as function of DTS and triangulation angle. To mimic the scenario of spine SBRT, the effect on the standard deviation of megavoltage radiation delivery during kV image acquisition was tested. In addition, the ability of the system to detect different types of movement was investigated for a variety of small sudden and gradual movements during kV image acquisition.

  16. X-ray digital intra-oral tomosynthesis for quasi-three-dimensional imaging: system, reconstruction algorithm, and experiments

    NASA Astrophysics Data System (ADS)

    Li, Liang; Chen, Zhiqiang; Zhao, Ziran; Wu, Dufan

    2013-01-01

    At present, there are mainly three x-ray imaging modalities for dental clinical diagnosis: radiography, panorama and computed tomography (CT). We develop a new x-ray digital intra-oral tomosynthesis (IDT) system for quasi-three-dimensional dental imaging which can be seen as an intermediate modality between traditional radiography and CT. In addition to normal x-ray tube and digital sensor used in intra-oral radiography, IDT has a specially designed mechanical device to complete the tomosynthesis data acquisition. During the scanning, the measurement geometry is such that the sensor is stationary inside the patient's mouth and the x-ray tube moves along an arc trajectory with respect to the intra-oral sensor. Therefore, the projection geometry can be obtained without any other reference objects, which makes it be easily accepted in clinical applications. We also present a compressed sensing-based iterative reconstruction algorithm for this kind of intra-oral tomosynthesis. Finally, simulation and experiment were both carried out to evaluate this intra-oral imaging modality and algorithm. The results show that IDT has its potentiality to become a new tool for dental clinical diagnosis.

  17. Algorithmic scatter correction in dual-energy digital mammography

    SciTech Connect

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

    2013-11-15

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

  18. SU-E-P-31: Quantifying the Amount of Missing Tissue in a Digital Breast Tomosynthesis

    SciTech Connect

    Goodenough, D; Olafsdottir, H; Olafsson, I; Fredriksson, J; Kristinsson, S; Oskarsdottir, G; Kristbjornsson, A; Mallozzi, R; Healy, A; Levy, J

    2015-06-15

    Purpose: To automatically quantify the amount of missing tissue in a digital breast tomosynthesis system using four stair-stepped chest wall missing tissue gauges in the Tomophan™ from the Phantom Laboratory and image processing from Image Owl. Methods: The Tomophan™ phantom incorporates four stair-stepped missing tissue gauges by the chest wall, allowing measurement of missing chest wall in two different locations along the chest wall at two different heights. Each of the four gauges has 12 steps in 0.5 mm increments rising from the chest wall. An image processing algorithm was developed by Image Owl that first finds the two slices containing the steps then finds the signal through the highest step in all four gauges. Using the signal drop at the beginning of each gauge the distance to the end of the image gives the length of the missing tissue gauge in millimeters. Results: The Tomophan™ was imaged in digital breast tomosynthesis (DBT) systems from various vendors resulting in 46 cases used for testing. The results showed that on average 1.9 mm of 6 mm of the gauges are visible. A small focus group was asked to count the number of visible steps for each case which resulted in a good agreement between observer counts and computed data. Conclusion: First, the results indicate that the amount of missing chest wall can differ between vendors. Secondly it was shown that an automated method to estimate the amount of missing chest wall gauges agreed well with observer assessments. This finding indicates that consistency testing may be simplified using the Tomophan™ phantom and analysis by an automated image processing named Tomo QA. In general the reason for missing chest wall may be due to a function of the beam profile at the chest wall as DBT projects through the angular sampling. Research supported by Image Owl, Inc., The Phantom Laboratory, Inc. and Raforninn ehf; Mallozzi and Healy employed by The Phantom Laboratory, Inc.; Goodenough is a consultant to The

  19. Sensitivity of Thoracic Digital Tomosynthesis (DTS) for the Identification of Lung Nodules.

    PubMed

    Langer, Steve G; Graner, Brian D; Schueler, Beth A; Fetterly, Kenneth A; Kofler, James M; Mandrekar, Jayawant N; Bartholmai, Brian J

    2016-02-01

    Thoracic computed tomography (CT) is considered the gold standard for detection lung pathology, yet its efficacy as a screening tool in regards to cost and radiation dose continues to evolve. Chest radiography (CXR) remains a useful and ubiquitous tool for detection and characterization of pulmonary pathology, but reduced sensitivity and specificity compared to CT. This prospective, blinded study compares the sensitivity of digital tomosynthesis (DTS), to that of CT and CXR for the identification and characterization of lung nodules. Ninety-five outpatients received a posteroanterior (PA) and lateral CXR, DTS, and chest CT at one care episode. The CXR and DTS studies were independently interpreted by three thoracic radiologists. The CT studies were used as the gold standard and read by a fourth thoracic radiologist. Nodules were characterized by presence, location, size, and composition. The agreement between observers and the effective radiation dose for each modality was objectively calculated. One hundred forty-five nodules of greatest diameter larger than 4 mm and 215 nodules less than 4 mm were identified by CT. DTS identified significantly more >4 mm nodules than CXR (DTS 32 % vs. CXR 17 %). CXR and DTS showed no significant difference in the ability to identify the smaller nodules or central nodules within 3 cm of the hilum. DTS outperformed CXR in identifying pleural nodules and those nodules located greater than 3 cm from the hilum. Average radiation dose for CXR, DTS, and CT were 0.10, 0.21, and 6.8 mSv, respectively. Thoracic digital tomosynthesis requires significantly less radiation dose than CT and nearly doubles the sensitivity of that of CXR for the identification of lung nodules greater than 4 mm. However, sensitivity and specificity for detection and characterization of lung nodules remains substantially less than CT. The apparent benefits over CXR, low cost, rapid acquisition, and minimal radiation dose of thoracic DTS suggest that it may be a

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

    PubMed Central

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

    2012-01-01

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

  1. On imaging with or without grid in digital mammography

    NASA Astrophysics Data System (ADS)

    Chen, Han; Danielsson, Mats; Cederström, Björn

    2014-03-01

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

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

    SciTech Connect

    Delgado-Gonzalez, A.

    2008-08-11

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

  3. Statistical iterative reconstruction using fast optimization transfer algorithm with successively increasing factor in Digital Breast Tomosynthesis

    NASA Astrophysics Data System (ADS)

    Xu, Shiyu; Zhang, Zhenxi; Chen, Ying

    2014-03-01

    Statistical iterative reconstruction exhibits particularly promising since it provides the flexibility of accurate physical noise modeling and geometric system description in transmission tomography system. However, to solve the objective function is computationally intensive compared to analytical reconstruction methods due to multiple iterations needed for convergence and each iteration involving forward/back-projections by using a complex geometric system model. Optimization transfer (OT) is a general algorithm converting a high dimensional optimization to a parallel 1-D update. OT-based algorithm provides a monotonic convergence and a parallel computing framework but slower convergence rate especially around the global optimal. Based on an indirect estimation on the spectrum of the OT convergence rate matrix, we proposed a successively increasing factor- scaled optimization transfer (OT) algorithm to seek an optimal step size for a faster rate. Compared to a representative OT based method such as separable parabolic surrogate with pre-computed curvature (PC-SPS), our algorithm provides comparable image quality (IQ) with fewer iterations. Each iteration retains a similar computational cost to PC-SPS. The initial experiment with a simulated Digital Breast Tomosynthesis (DBT) system shows that a total 40% computing time is saved by the proposed algorithm. In general, the successively increasing factor-scaled OT exhibits a tremendous potential to be a iterative method with a parallel computation, a monotonic and global convergence with fast rate.

  4. Three-Dimensional Computer-Aided Detection of Microcalcification Clusters in Digital Breast Tomosynthesis

    PubMed Central

    Jeong, Ji-wook; Chae, Seung-Hoon; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook; Lee, Sooyeul

    2016-01-01

    We propose computer-aided detection (CADe) algorithm for microcalcification (MC) clusters in reconstructed digital breast tomosynthesis (DBT) images. The algorithm consists of prescreening, MC detection, clustering, and false-positive (FP) reduction steps. The DBT images containing the MC-like objects were enhanced by a multiscale Hessian-based three-dimensional (3D) objectness response function and a connected-component segmentation method was applied to extract the cluster seed objects as potential clustering centers of MCs. Secondly, a signal-to-noise ratio (SNR) enhanced image was also generated to detect the individual MC candidates and prescreen the MC-like objects. Each cluster seed candidate was prescreened by counting neighboring individual MC candidates nearby the cluster seed object according to several microcalcification clustering criteria. As a second step, we introduced bounding boxes for the accepted seed candidate, clustered all the overlapping cubes, and examined. After the FP reduction step, the average number of FPs per case was estimated to be 2.47 per DBT volume with a sensitivity of 83.3%. PMID:27274993

  5. Segmentation methods for breast vasculature in dual-energy contrast-enhanced digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Lau, Kristen C.; Lee, Hyo Min; Singh, Tanushriya; Maidment, Andrew D. A.

    2015-03-01

    Dual-energy contrast-enhanced digital breast tomosynthesis (DE CE-DBT) uses an iodinated contrast agent to image the three-dimensional breast vasculature. The University of Pennsylvania has an ongoing DE CE-DBT clinical study in patients with known breast cancers. The breast is compressed continuously and imaged at four time points (1 pre-contrast; 3 post-contrast). DE images are obtained by a weighted logarithmic subtraction of the high-energy (HE) and low-energy (LE) image pairs. Temporal subtraction of the post-contrast DE images from the pre-contrast DE image is performed to analyze iodine uptake. Our previous work investigated image registration methods to correct for patient motion, enhancing the evaluation of vascular kinetics. In this project we investigate a segmentation algorithm which identifies blood vessels in the breast from our temporal DE subtraction images. Anisotropic diffusion filtering, Gabor filtering, and morphological filtering are used for the enhancement of vessel features. Vessel labeling methods are then used to distinguish vessel and background features successfully. Statistical and clinical evaluations of segmentation accuracy in DE-CBT images are ongoing.

  6. Investigation on location-dependent detectability of a small mass for digital breast tomosynthesis evaluation

    NASA Astrophysics Data System (ADS)

    Lee, Changwoo; Baek, Jongduk; Park, Subok

    2016-03-01

    Digital breast tomosynthesis (DBT) is an emerging imaging modality for improved breast cancer detection and diagnosis [1-5]. Numerous efforts have been made to find quantitative metrics associated with mammographic image quality assessment, such as the exponent β of anatomical noise power spectrum, glandularity, contrast noise ratio, etc. [6-8]. In addition, with the use of Fourier-domain detectability for a task-based assessment of DBT, a stationarity assumption on reconstructed image statistics was often made [9-11], resulting in the use of multiple regions-of-interest (ROIs) from different locations in order to increase sample size. While all these metrics provide some information on mammographic image characteristics and signal detection, the relationship between these metrics and detectability in DBT evaluation has not been fully understood. In this work, we investigated spatial-domain detectability trends and levels as a function of the number of slices Ns at three different ROI locations on the same image slice, where background statistics differ in terms of the aforementioned metrics. Detectabilities for the three ROI locations were calculated using multi-slice channelized Hotelling observers with 2D/3D Laguerre-Gauss channels. Our simulation results show that detectability levels and trends as a function of Ns vary across these three ROI locations. They also show that the exponent β, mean glandularity, and mean attenuation coefficient vary across the three ROI locations but they do not necessarily predict the ranking of detectability levels and trends across these ROI locations.

  7. Three-Dimensional Computer-Aided Detection of Microcalcification Clusters in Digital Breast Tomosynthesis.

    PubMed

    Jeong, Ji-Wook; Chae, Seung-Hoon; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook; Lee, Sooyeul

    2016-01-01

    We propose computer-aided detection (CADe) algorithm for microcalcification (MC) clusters in reconstructed digital breast tomosynthesis (DBT) images. The algorithm consists of prescreening, MC detection, clustering, and false-positive (FP) reduction steps. The DBT images containing the MC-like objects were enhanced by a multiscale Hessian-based three-dimensional (3D) objectness response function and a connected-component segmentation method was applied to extract the cluster seed objects as potential clustering centers of MCs. Secondly, a signal-to-noise ratio (SNR) enhanced image was also generated to detect the individual MC candidates and prescreen the MC-like objects. Each cluster seed candidate was prescreened by counting neighboring individual MC candidates nearby the cluster seed object according to several microcalcification clustering criteria. As a second step, we introduced bounding boxes for the accepted seed candidate, clustered all the overlapping cubes, and examined. After the FP reduction step, the average number of FPs per case was estimated to be 2.47 per DBT volume with a sensitivity of 83.3%. PMID:27274993

  8. Evaluation of effective dose with chest digital tomosynthesis system using Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Kim, Dohyeon; Jo, Byungdu; Lee, Youngjin; Park, Su-Jin; Lee, Dong-Hoon; Kim, Hee-Joung

    2015-03-01

    Chest digital tomosynthesis (CDT) system has recently been introduced and studied. This system offers the potential to be a substantial improvement over conventional chest radiography for the lung nodule detection and reduces the radiation dose with limited angles. PC-based Monte Carlo program (PCXMC) simulation toolkit (STUK, Helsinki, Finland) is widely used to evaluate radiation dose in CDT system. However, this toolkit has two significant limits. Although PCXMC is not possible to describe a model for every individual patient and does not describe the accurate X-ray beam spectrum, Geant4 Application for Tomographic Emission (GATE) simulation describes the various size of phantom for individual patient and proper X-ray spectrum. However, few studies have been conducted to evaluate effective dose in CDT system with the Monte Carlo simulation toolkit using GATE. The purpose of this study was to evaluate effective dose in virtual infant chest phantom of posterior-anterior (PA) view in CDT system using GATE simulation. We obtained the effective dose at different tube angles by applying dose actor function in GATE simulation which was commonly used to obtain the medical radiation dosimetry. The results indicated that GATE simulation was useful to estimate distribution of absorbed dose. Consequently, we obtained the acceptable distribution of effective dose at each projection. These results indicated that GATE simulation can be alternative method of calculating effective dose in CDT applications.

  9. Application of digital tomosynthesis (DTS) of optimal deblurring filters for dental X-ray imaging

    NASA Astrophysics Data System (ADS)

    Oh, J. E.; Cho, H. S.; Kim, D. S.; Choi, S. I.; Je, U. K.

    2012-04-01

    Digital tomosynthesis (DTS) is a limited-angle tomographic technique that provides some of the tomographic benefits of computed tomography (CT) but at reduced dose and cost. Thus, the potential for application of DTS to dental X-ray imaging seems promising. As a continuation of our dental radiography R&D, we developed an effective DTS reconstruction algorithm and implemented it in conjunction with a commercial dental CT system for potential use in dental implant placement. The reconstruction algorithm employed a backprojection filtering (BPF) method based upon optimal deblurring filters to suppress effectively both the blur artifacts originating from the out-focus planes and the high-frequency noise. To verify the usefulness of the reconstruction algorithm, we performed systematic simulation works and evaluated the image characteristics. We also performed experimental works in which DTS images of enhanced anatomical resolution were successfully obtained by using the algorithm and were promising to our ongoing applications to dental X-ray imaging. In this paper, our approach to the development of the DTS reconstruction algorithm and the results are described in detail.

  10. Initial experience with computer aided detection for microcalcification in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Harkness, E. F.; Lim, Y. Y.; Wilson, M. W.; Haq, R.; Zhou, J.; Tate, C.; Maxwell, A. J.; Astley, S. M.; Gilbert, F. J.

    2015-03-01

    Digital breast tomosynthesis (DBT) addresses limitations of 2-D projection imaging for detection of masses. Microcalcification clusters may be more difficult to appreciate in DBT as individual calcifications within clusters may appear on different slices. This research aims to evaluate the performance of ImageChecker 3D Calc CAD v1.0. Women were recruited as part of the TOMMY trial. From the trial, 169 were included in this study. The DBT images were processed with the computer aided detection (CAD) algorithm. Three consultant radiologists reviewed the images and recorded whether CAD prompts were on or off target. 79/80 (98.8%) malignant cases had a prompt on the area of microcalcification. In these cases, there were 1-15 marks (median 5) with the majority of false prompts (n=326/431) due to benign (68%) and vascular (24%) calcifications. Of 89 normal/benign cases, there were 1-13 prompts (median 3), 27 (30%) had no prompts and the majority of false prompts (n=238) were benign (77%) calcifications. CAD is effective in prompting malignant microcalcification clusters and may overcome the difficulty of detecting clusters in slice images. Although there was a high rate of false prompts, further advances in the software may improve specificity.

  11. Evaluation and optimization of the maximum-likelihood approach for image reconstruction in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Jerebko, Anna K.; Mertelmeier, Thomas

    2010-04-01

    Digital Breast Tomosynthesis (DBT) suffers from incomplete data and poor quantum statistics limited by the total dose absorbed in the breast. Hence, statistical reconstruction assuming the photon statistics to follow a Poisson distribution may have some advantages. This study investigates state-of-art iterative maximum likelihood (ML) statistical reconstruction algorithms for DBT and compares the results with simple backprojection (BP), filtered backprojection (FBP), and iFBP (FBP with filter derived from iterative reconstruction). The gradient-ascent and convex optimization variants of the transmission ML algorithm are evaluated with phantom and clinical data. Convergence speed is very similar for both iterative statistical algorithms and after approximately 5 iterations all significant details are well displayed, although we notice increasing noise. We found empirically that a relaxation factor between 0.25 and 0.5 provides the optimal trade-off between noise and contrast. The ML-convex algorithm gives smoother results than the ML-gradient algorithm. The low-contrast CNR of the ML algorithms is between CNR for simple backprojection (highest) and FBP (lowest). Spatial resolution of iterative statistical and iFBP algorithms is similar to that of FBP but the quantitative density representation better resembles conventional mammograms. The iFBP algorithm provides the benefits of statistical iterative reconstruction techniques and requires much shorter computation time.

  12. Detection method of visible and invisible nipples on digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Chae, Seung-Hoon; Jeong, Ji-Wook; Lee, Sooyeul; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook

    2015-03-01

    Digital Breast Tomosynthesis(DBT) with 3D breast image can improve detection sensitivity of breast cancer more than 2D mammogram on dense breast. The nipple location information is needed to analyze DBT. The nipple location is invaluable information in registration and as a reference point for classifying mass or micro-calcification clusters. Since there are visible nipple and invisible nipple in 2D mammogram or DBT, the nipple detection of breast must be possible to detect visible and invisible nipple of breast. The detection method of visible nipple using shape information of nipple is simple and highly efficient. However, it is difficult to detect invisible nipple because it doesn't have prominent shape. Mammary glands in breast connect nipple, anatomically. The nipple location is detected through analyzing location of mammary glands in breast. In this paper, therefore, we propose a method to detect the nipple on a breast, which has a visible or invisible nipple using changes of breast area and mammary glands, respectively. The result shows that our proposed method has average error of 2.54+/-1.47mm.

  13. Image reconstruction for digital breast tomosynthesis (DBT) by using projection-angle-dependent filter functions

    NASA Astrophysics Data System (ADS)

    Park, Yeonok; Park, Chulkyu; Cho, Hyosung; Je, Uikyu; Hong, Daeki; Lee, Minsik; Cho, Heemoon; Choi, Sungil; Koo, Yangseo

    2014-09-01

    Digital breast tomosynthesis (DBT) is considered in clinics as a standard three-dimensional imaging modality, allowing the earlier detection of cancer. It typically acquires only 10-30 projections over a limited angle range of 15-60° with a stationary detector and typically uses a computationally-efficient filtered-backprojection (FBP) algorithm for image reconstruction. However, a common FBP algorithm yields poor image quality resulting from the loss of average image value and the presence of severe image artifacts due to the elimination of the dc component of the image by the ramp filter and to the incomplete data, respectively. As an alternative, iterative reconstruction methods are often used in DBT to overcome these difficulties, even though they are still computationally expensive. In this study, as a compromise, we considered a projection-angle-dependent filtering method in which one-dimensional geometry-adapted filter kernels are computed with the aid of a conjugate-gradient method and are incorporated into the standard FBP framework. We implemented the proposed algorithm and performed systematic simulation works to investigate the imaging characteristics. Our results indicate that the proposed method is superior to a conventional FBP method for DBT imaging and has a comparable computational cost, while preserving good image homogeneity and edge sharpening with no serious image artifacts.

  14. Enhanced imaging of microcalcifications in digital breast tomosynthesis through improved image-reconstruction algorithms

    SciTech Connect

    Sidky, Emil Y.; Pan Xiaochuan; Reiser, Ingrid S.; Nishikawa, Robert M.; Moore, Richard H.; Kopans, Daniel B.

    2009-11-15

    Purpose: The authors develop a practical, iterative algorithm for image-reconstruction in undersampled tomographic systems, such as digital breast tomosynthesis (DBT). Methods: The algorithm controls image regularity by minimizing the image total p variation (TpV), a function that reduces to the total variation when p=1.0 or the image roughness when p=2.0. Constraints on the image, such as image positivity and estimated projection-data tolerance, are enforced by projection onto convex sets. The fact that the tomographic system is undersampled translates to the mathematical property that many widely varied resultant volumes may correspond to a given data tolerance. Thus the application of image regularity serves two purposes: (1) Reduction in the number of resultant volumes out of those allowed by fixing the data tolerance, finding the minimum image TpV for fixed data tolerance, and (2) traditional regularization, sacrificing data fidelity for higher image regularity. The present algorithm allows for this dual role of image regularity in undersampled tomography. Results: The proposed image-reconstruction algorithm is applied to three clinical DBT data sets. The DBT cases include one with microcalcifications and two with masses. Conclusions: Results indicate that there may be a substantial advantage in using the present image-reconstruction algorithm for microcalcification imaging.

  15. Detection of lung nodules in chest digital tomosynthesis (CDT): effects of the different angular dose distribution

    NASA Astrophysics Data System (ADS)

    Jo, Byungdu; Lee, Youngjin; Kim, Dohyeon; Lee, Dong-Hoon; Jin, Seong-Soo; Mu, Shou-Chih; Kim, Hye-Mi; Kim, Hee-Joung

    2015-03-01

    Chest digital tomosynthesis (CDT) is a recently introduced new imaging modality for better detection of high- and smallcontrast lung nodules compared to conventional X-ray radiography. In CDT system, several projection views need to be acquired with limited angular range. The acquisition of insufficient number of projection data can degrade the reconstructed image quality. This image degradation easily affected by acquisition parameters such as angular dose distribution, number of projection views and reconstruction algorithm. To investigate the imaging characteristics, we evaluated the impact of the angular dose distribution on image quality by simulation studies with Geant4 Application for Tomographic Emission (GATE). We designed the different angular dose distribution conditions. The results showed that the contrast-to-noise ratio (CNR) improves when exposed the higher dose at central projection views than peripheral views. While it was found that increasing angular dose distribution at central views improved lung nodule detectability, although both peripheral regions slightly suffer from image noise due to low dose distribution. The improvements of CNR by using proposed image acquisition technique suggest possible directions for further improvement of CDT system for lung nodule detection with high quality imaging capabilities.

  16. Utilizing digital breast tomosynthesis projection views correlation for microcalcification enhancement for detection purposes

    NASA Astrophysics Data System (ADS)

    Baddar, Wissam J.; Kim, Eun Joon; Kim, Dae Hoe; Ro, Yong Man

    2015-03-01

    This paper presents a novel method for enhancing the contrast of microcalcifications in digital breast tomosynthesis projection views for detection purposes. The proposed method relies on the correlation between the projection views in order to reduce the effect of noise, due to the low-dose exposure, and increase the contrast of the microcalcification particles for microcalcification cluster detection purposes. The method performs a series of multi-shift operations to capture the microcalcification particle movement information and compensate it in order to enhance microcalcification particles contrast. Furthermore, the proposed approach utilizes the projection view correlation in order to reduce the falsely detected regions of interest, and improve the classification of the detected regions into false positives or actual microcalcification clusters. Comparative experiments have been performed to quantitatively measure the contrast enhancement of microcalcification particles and its effect on the MC cluster detection. To that end, the contrast to noise ratio have been calculated and compared with some with previous methods. Furthermore, the free response receiver operating characteristic (FROC) curve have been used to measure the effect of the proposed enhancement on the microcalcification cluster detectability.

  17. Optimizing the acquisition geometry for digital breast tomosynthesis using the Defrise phantom

    NASA Astrophysics Data System (ADS)

    Acciavatti, Raymond J.; Chang, Alice; Woodbridge, Laura; Maidment, Andrew D. A.

    2014-03-01

    In cone beam computed tomography (CT), it is common practice to use the Defrise phantom for image quality assessment. The phantom consists of a stack of plastic plates with low frequency spacing. Because the x-ray beam may traverse multiple plates, the spacing between plates can appear blurry in the reconstruction, and hence modulation provides a measure of image quality. This study considers the potential merit of using the Defrise phantom in digital breast tomosynthesis (DBT), a modality with a smaller projection range than CT. To this end, a Defrise phantom was constructed and subsequently imaged with a commercial DBT system. It was demonstrated that modulation is dependent on position and orientation in the reconstruction. Modulation is preserved over a broad range of positions along the chest wall if the input frequency is oriented in the tube travel direction. By contrast, modulation is degraded with increasing distance from the chest wall if the input frequency is oriented in the posteroanterior (PA) direction. A theoretical framework was then developed to model these results. Reconstructions were calculated in an acquisition geometry designed to improve modulation. Unlike current geometries in which the x-ray tube motion is restricted to the plane of the chest wall, we consider a geometry with an additional component of tube motion along the PA direction. In simulations, it is shown that the newly proposed geometry improves modulation at positions distal to the chest wall. In conclusion, this study demonstrates that the Defrise phantom is a tool for optimizing DBT systems.

  18. Sensitivity analysis of a geometric calibration method using projection matrices for digital tomosynthesis systems

    SciTech Connect

    Li Xinhua; Zhang Da; Liu, Bob

    2011-01-15

    Purpose: To study the sensitivity of a geometric calibration method using projection matrices for digital tomosynthesis systems. Methods: A generic geometric calibration method for tomographic imaging systems has been presented in our previous work. The method involves a scan of a calibration phantom with multiple markers. Their locations in projection images are detected and are associated with their 3D coordinates to compute 3x4 projection matrices, which can be used in subsequent image reconstruction. The accuracy of geometric calibration may be affected by errors in the input data of marker positions. The effects of errors may depend on the number of markers and the volume surrounded by them in 3D space. This work analyzed the sensitivity of the calibration method to the above factors. A 6 cm CIRS breast research phantom and a prototype breast tomosynthesis system were used for our tests. A high contrast ring and two small speck groups were reconstructed in various testing cases for comparison. To achieve quantitative assessment, a 15x15 point detection mask was adopted for detecting signals and for computing changes between testing cases and the regular geometric calibration. Results: When 3D coordinates and 2D projections of markers were accurate, all tested numbers of markers, 6-44, provided similar high quality reconstructions of the ring and the two speck groups. Errors in marker positions resulted in image degradations and signal changes, which increased with fewer markers and smaller volume surrounded by markers in the 3D object space. Signal changes of small specks were more significant than those of the ring. Errors in marker projections produced drastic image degradations. Coplanar marker placement caused a failure in projection matrix computation. Conclusions: For practical geometric calibration phantom design, ample markers are desired. They need to have a large volumetric coverage in the 3D space and be far from being coplanar. Precise

  19. Evaluation of a variable dose acquisition technique for microcalcification and mass detection in digital breast tomosynthesis

    SciTech Connect

    Das, Mini; Gifford, Howard C.; O'Connor, J. Michael; Glick, Stephen J.

    2009-06-15

    In this article the authors evaluate a recently proposed variable dose (VD)-digital breast tomosynthesis (DBT) acquisition technique in terms of the detection accuracy for breast masses and microcalcification (MC) clusters. With this technique, approximately half of the total dose is used for one center projection and the remaining dose is split among the other tomosynthesis projection views. This acquisition method would yield both a projection view and a reconstruction view. One of the aims of this study was to evaluate whether the center projection alone of the VD acquisition can provide equal or superior MC detection in comparison to the 3D images from uniform dose (UD)-DBT. Another aim was to compare the mass-detection capabilities of 3D reconstructions from VD-DBT and UD-DBT. In a localization receiver operating characteristic (LROC) observer study of MC detection, the authors compared the center projection of a VD acquisition scheme (at 2 mGy dose) with detector pixel size of 100 {mu}m with the UD-DBT reconstruction (at 4 mGy dose) obtained with a voxel size of 100 {mu}m. MCs with sizes of 150 and 180 {mu}m were used in the study, with each cluster consisting of seven MCs distributed randomly within a small volume. Reconstructed images in UD-DBT were obtained from a projection set that had a total of 4 mGy dose. The current study shows that for MC detection, using the center projection alone of VD acquisition scheme performs worse with area under the LROC curve (A{sub L}) of 0.76 than when using the 3D reconstructed image using the UD acquisition scheme (A{sub L}=0.84). A 2D ANOVA found a statistically significant difference (p=0.038) at a significance level of 0.05. In the current study, although a reconstructed image was also available using the VD acquisition scheme, it was not used to assist the MC detection task which was done using the center projection alone. In the case of evaluation of detection accuracy of masses, the reconstruction with VD-DBT (A

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

    SciTech Connect

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

    2006-03-15

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

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-05

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

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

    PubMed

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

    2009-03-01

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

  3. 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.

  4. Accurate joint space quantification in knee osteoarthritis: a digital x-ray tomosynthesis phantom study

    NASA Astrophysics Data System (ADS)

    Sewell, Tanzania S.; Piacsek, Kelly L.; Heckel, Beth A.; Sabol, John M.

    2011-03-01

    The current imaging standard for diagnosis and monitoring of knee osteoarthritis (OA) is projection radiography. However radiographs may be insensitive to markers of early disease such as osteophytes and joint space narrowing (JSN). Relative to standard radiography, digital X-ray tomosynthesis (DTS) may provide improved visualization of the markers of knee OA without the interference of superimposed anatomy. DTS utilizes a series of low-dose projection images over an arc of +/-20 degrees to reconstruct tomographic images parallel to the detector. We propose that DTS can increase accuracy and precision in JSN quantification. The geometric accuracy of DTS was characterized by quantifying joint space width (JSW) as a function of knee flexion and position using physical and anthropomorphic phantoms. Using a commercially available digital X-ray system, projection and DTS images were acquired for a Lucite rod phantom with known gaps at various source-object-distances, and angles of flexion. Gap width, representative of JSW, was measured using a validated algorithm. Over an object-to-detector-distance range of 5-21cm, a 3.0mm gap width was reproducibly measured in the DTS images, independent of magnification. A simulated 0.50mm (+/-0.13) JSN was quantified accurately (95% CI 0.44-0.56mm) in the DTS images. Angling the rods to represent knee flexion, the minimum gap could be precisely determined from the DTS images and was independent of flexion angle. JSN quantification using DTS was insensitive to distance from patient barrier and flexion angle. Potential exists for the optimization of DTS for accurate radiographic quantification of knee OA independent of patient positioning.

  5. Breast tomosynthesis imaging configuration analysis.

    PubMed

    Rayford, Cleveland E; Zhou, Weihua; Chen, Ying

    2013-01-01

    Traditional two-dimensional (2D) X-ray mammography is the most commonly used method for breast cancer diagnosis. Recently, a three-dimensional (3D) Digital Breast Tomosynthesis (DBT) system has been invented, which is likely to challenge the current mammography technology. The DBT system provides stunning 3D information, giving physicians increased detail of anatomical information, while reducing the chance of false negative screening. In this research, two reconstruction algorithms, Back Projection (BP) and Shift-And-Add (SAA), were used to investigate and compare View Angle (VA) and the number of projection images (N) with parallel imaging configurations. In addition, in order to better determine which method displayed better-quality imaging, Modulation Transfer Function (MTF) analyses were conducted with both algorithms, ultimately producing results which improve upon better breast cancer detection. Research studies find evidence that early detection of the disease is the best way to conquer breast cancer, and earlier detection results in the increase of life span for the affected person. PMID:23900440

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

    PubMed

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

    2016-04-01

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

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

    PubMed

    2000-01-01

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

  8. SU-D-BRF-04: Digital Tomosynthesis for Improved Daily Setup in Treatment of Liver Lesions

    SciTech Connect

    Armstrong, H; Jones, B; Miften, M

    2014-06-01

    Purpose: Daily localization of liver lesions with cone-beam CT (CBCT) is difficult due to poor image quality caused by scatter, respiratory motion, and the lack of radiographic contrast between the liver parenchyma and the lesion(s). Digital tomosynthesis (DTS) is investigated as a modality to improve liver visualization and lesion/parenchyma contrast for daily setup. Methods: An in-house tool was developed to generate DTS images using a point-by-point filtered back-projection method from on-board CBCT projection data. DTS image planes are generated in a user defined orientation to visualize the anatomy at various depths. Reference DTS images are obtained from forward projection of the planning CT dataset at each projection angle. The CBCT DTS image set can then be registered to the reference DTS image set as a means for localization. Contour data from the planning CT's associate RT Structure file and forward projected similarly to the planning CT data. DTS images are created for each contoured structure, which can then be overlaid onto the DTS images for organ volume visualization. Results: High resolution DTS images generated from CBCT projections show fine anatomical detail, including small blood vessels, within the patient. However, the reference DTS images generated from forward projection of the planning CT lacks this level of detail due to the low resolution of the CT voxels as compared to the pixel size in the projection images; typically 1mm-by-1mm-by-3mm (lat, vrt, lng) for the planning CT vs. 0.4mm-by-0.4mm for CBCT projections. Overlaying of the contours onto the DTS image allows for visualization of structures of interest. Conclusion: The ability to generate DTS images over a limited range of projection angles allows for reduction in the amount of respiratory motion within each acquisition. DTS may provide improved visualization of structures and lesions as compared to CBCT for highly mobile tumors.

  9. Digital breast tomosynthesis: computerized detection of microcalcifications in reconstructed breast volume using a 3D approach

    NASA Astrophysics Data System (ADS)

    Chan, Heang-Ping; Sahiner, Berkman; Wei, Jun; Hadjiiski, Lubomir M.; Zhou, Chuan; Helvie, Mark A.

    2010-03-01

    We are developing a computer-aided detection (CAD) system for clustered microcalcifications in digital breast tomosynthesis (DBT). In this preliminary study, we investigated the approach of detecting microcalcifications in the tomosynthesized volume. The DBT volume is first enhanced by 3D multi-scale filtering and analysis of the eigenvalues of Hessian matrices with a calcification response function and signal-to-noise ratio enhancement filtering. Potential signal sites are identified in the enhanced volume and local analysis is performed to further characterize each object. A 3D dynamic clustering procedure is designed to locate potential clusters using hierarchical criteria. We collected a pilot data set of two-view DBT mammograms of 39 breasts containing microcalcification clusters (17 malignant, 22 benign) with IRB approval. A total of 74 clusters were identified by an experienced radiologist in the 78 DBT views. Our prototype CAD system achieved view-based sensitivity of 90% and 80% at an average FP rate of 7.3 and 2.0 clusters per volume, respectively. At the same levels of case-based sensitivity, the FP rates were 3.6 and 1.3 clusters per volume, respectively. For the subset of malignant clusters, the view-based detection sensitivity was 94% and 82% at an average FP rate of 6.0 and 1.5 FP clusters per volume, respectively. At the same levels of case-based sensitivity, the FP rates were 1.2 and 0.9 clusters per volume, respectively. This study demonstrated that computerized microcalcification detection in 3D is a promising approach to the development of a CAD system for DBT. Study is underway to further improve the computer-vision methods and to optimize the processing parameters using a larger data set.

  10. 3D view weighted cone-beam backprojection reconstruction for digital tomosynthesis

    NASA Astrophysics Data System (ADS)

    Li, Baojun; Avinash, Gopal; Claus, Bernhard; Metz, Stephen

    2007-03-01

    Cone-beam filtered backprojection (CB-FBP) is one of the major reconstruction algorithms for digital tomosynthesis. In conventional FBP, the photon fluxes in projections are evenly distributed along the X-ray beam. Due to the limited view angles and finite detector dimensions, this uniform weighting causes non-uniformity in the recon images and leads to cone-beam artifact. In this paper, we propose a 3-D view weighting technique in combination with FBP to combat this artifact. An anthropomorphic chest phantom was placed at supine position to enable the imaging of chest PA view. During a linear sweep of X-ray source, 41 X-ray images at different projection angles were acquired with the following protocol: 120kVp, 160mA, and 0.64mAs/exposure. To create the worst scenario for testing, we chose 60 degrees as the sweep angle in this exam. The data set was reconstructed with conventional CB-FBP and proposed algorithm under the same parameters: FOV = 40x40 cm^2, and slice thickness = 4mm. 3 recon slices were randomly selected for review with slice height = 10.5/14.5/17.5cm. Results were assessed qualitatively by human observers and quantitatively through ROI measurement. In each slice, three pre-defined ROIs (50x50 pixels)--ROI A and B are in artifact more pronounced area, and ROI C is in relatively artifact-free area--are extracted and measured. The non-uniformity error was defined as the ratio of MEAN(AVG(C-A), AVG(C-B)) / AVG(C). The average non-uniformity error over the three test images was 0.428 for without view weighting and only 0.041 for with view weighting.

  11. Quantitative comparison of spatial resolution in step-and-shoot and continuous motion digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Ghani, Muhammad U.; Wu, Di; Wong, Molly D.; Ren, Liqiang; Zheng, Bin; Yang, Kai; Wu, Xizeng; Liu, Hong

    2016-03-01

    This study compares the spatial resolution in step-and-shoot and continuous motion acquisition modes of digital tomosynthesis using a bench-top prototype designed for breast phantoms imaging. The prototype employs a flat panel detector with a 50 μm pixel pitch, a micro focus x-ray tube and a motorized stage. A sharp metal edge with a thickness of 0.2 mm was used to measure the modulation transfer function (MTF). The edge was rotated from -7.5° to +7.5° with 1.5° increments to acquire 11 angular projections using 40 kVp, 500 μA with 5.55 s per projection. In continuous motion mode, the motorized stage moved the test object for the whole exposure time at a speed of 0.377 mm/s. The impact of acquisition speed in continuous DBT was also investigated, and a high speed of 0.753 mm/s was used. In step-and-shoot mode, the cutoff frequencies (10% MTF) in projection view (0°) and reconstructed DBT slices were 5.55 lp/mm and 4.95 lp/mm. Spatial resolution dropped in the continuous motion mode of the DBT due to the blur caused by the rotation of the stage and the cutoff frequencies reduced to 3.6 lp/mm and 3.18 lp/mm in the projection view (0º) and reconstructed DBT slices. At high rotational speed in continuous motion mode, the cutoff frequencies in the DBT slices dropped by 17 % to 2.65 lp/mm. Rotational speed of the rotation stage and spatial resolution are interconnected. Hence, reducing the motion blur in the continuous acquisition mode is important to maintain high spatial resolution for diagnostic purposes.

  12. A scatter correction method for contrast-enhanced dual-energy digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Lu, Yihuan; Peng, Boyu; Lau, Beverly A.; Hu, Yue-Houng; Scaduto, David A.; Zhao, Wei; Gindi, Gene

    2015-08-01

    Contrast-enhanced dual energy digital breast tomosynthesis (CE-DE-DBT) is designed to image iodinated masses while suppressing breast anatomical background. Scatter is a problem, especially for high energy acquisition, in that it causes severe cupping artifact and iodine quantitation errors. We propose a patient specific scatter correction (SC) algorithm for CE-DE-DBT. The empirical algorithm works by interpolating scatter data outside the breast shadow into an estimate within the breast shadow. The interpolated estimate is further improved by operations that use an easily obtainable (from phantoms) table of scatter-to-primary-ratios (SPR)—a single SPR value for each breast thickness and acquisition angle. We validated our SC algorithm for two breast emulating phantoms by comparing SPR from our SC algorithm to that measured using a beam-passing pinhole array plate. The error in our SC computed SPR, averaged over acquisition angle and image location, was about 5%, with slightly worse errors for thicker phantoms. The SC projection data, reconstructed using OS-SART, showed a large degree of decupping. We also observed that SC removed the dependence of iodine quantitation on phantom thickness. We applied the SC algorithm to a CE-DE-mammographic patient image with a biopsy confirmed tumor at the breast periphery. In the image without SC, the contrast enhanced tumor was masked by the cupping artifact. With our SC, the tumor was easily visible. An interpolation-based SC was proposed by (Siewerdsen et al 2006 Med. Phys. 33 187-97) for cone-beam CT (CBCT), but our algorithm and application differ in several respects. Other relevant SC techniques include Monte-Carlo and convolution-based methods for CBCT, storage of a precomputed library of scatter maps for DBT, and patient acquisition with a beam-passing pinhole array for breast CT. Our SC algorithm can be accomplished in clinically acceptable times, requires no additional imaging hardware or extra patient dose and is

  13. Directional MTF measurement using sphere phantoms for a digital breast tomosynthesis system

    NASA Astrophysics Data System (ADS)

    Lee, Changwoo; Baek, Jongduk

    2015-03-01

    The digital breast tomosynthesis (DBT) has been widely used as a diagnosis imaging modality of breast cancer because of potential for structure noise reduction, better detectability, and less breast compression. Since 3D modulation transfer function (MTF) is one of the quantitative metrics to assess the spatial resolution of medical imaging systems, it is very important to measure 3D MTF of the DBT system to evaluate the resolution performance. In order to do that, Samei et al. used sphere phantoms and applied Thornton's method to the DBT system. However, due to the limitation of Thornton's method, the low frequency drop, caused by the limited data acquisition angle and reconstruction filters, was not measured correctly. To overcome this limitation, we propose a Richardson-Lucy (RL) deconvolution based estimation method to measure the directional MTF. We reconstructed point and sphere objects using FDK algorithm within a 40⁰ data acquisition angle. The ideal 3D MTF is obtained by taking Fourier transform of the reconstructed point object, and three directions (i.e., fx-direction, fy-direction, and fxy-direction) of the ideal 3D MTF are used as a reference. To estimate the directional MTF, the plane integrals of the reconstructed and ideal sphere object were calculated and used to estimate the directional PSF using RL deconvolution technique. Finally, the directional MTF was calculated by taking Fourier transform of the estimated PSF. Compared to the previous method, the proposed method showed a good agreement with the ideal directional MTF, especially at low frequency regions.

  14. Digital Tomosynthesis for Respiratory Gated Liver Treatment: Clinical Feasibility for Daily Image Guidance

    SciTech Connect

    Wu, Q. Jackie; Meyer, Jeffrey; Fuller, Jessica; Godfrey, Devon; Wang Zhiheng; Zhang Junan; Yin Fangfang

    2011-01-01

    Purpose: Breath-hold (BH) treatment minimizes internal target volumes (ITV) when treating sites prone to motion. Digital tomosynthesis (DTS) imaging has advantages over cone-beam CT (CBCT) for BH imaging: BH-DTS scan can be completed during a single breath-hold, whereas BH-CBCT is usually acquired by parsing the gantry rotation into multiple BH segments. This study evaluates the localization accuracy of DTS for BH treatment of liver tumors. Methods: Both planning CT and on-board DTS/CBCT images were acquired under BH, using the planning CT BH window as reference. Onboard imaging data sets included two independent DTS orientations (coronal and sagittal), and CBCT images. Soft tissue target positioning was measured by each imaging modality and translated into couch shifts. Performance of the two DTS orientations was evaluated by comparing target positioning with the CBCT benchmark, determined by two observers. Results: Image data sets were collected from thirty-eight treatment fractions (14 patients). Mean differences between the two DTS methods and the CBCT method were <1 mm in all directions (except the lateral direction with sagittal-DTS: 1.2 mm); the standard deviation was in the range of 2.1-3.5 mm for all techniques. The Pearson correlation showed good interobserver agreement for the coronal-DTS (0.72-0.78). The interobserver agreement for the sagittal-DTS was good for the in-plane directions (0.70-0.82), but poor in the out-of-plane direction (lateral, 0.26). Conclusions: BH-DTS may be a simpler alternative to BH-CBCT for onboard soft tissue localization of the liver, although the precision of DTS localization appears to be somewhat lower because of the presence of subtle out-of-plane blur.

  15. Comparison of computerized mass detection in digital breast tomosynthesis (DBT) mammograms and conventional mammograms

    NASA Astrophysics Data System (ADS)

    Chan, Heang-Ping; Wei, Jun; Sahiner, Berkman; Hadjiiski, Lubomir; Helvie, Mark A.

    2009-02-01

    We are developing a CAD system for mass detection on digital breast tomosynthesis (DBT) mammograms. In this study, we compared the detection accuracy on DBT and conventional screen-film mammograms (SFMs). DBT mammograms were acquired with a GE prototype system at the University of Michigan. 47 cases containing the CC- and MLO-view DBT mammograms of the breast with a biopsy-proven mass and the corresponding two-view SFMs of the same breast were collected. Subjective judgment showed that the masses were much more conspicuous on DBT slices than on SFMs. The CAD system for DBT includes two parallel processes, one performs mass detection in the reconstructed DBT volume, and the other in the projection view (PV) images. The mass likelihood scores estimated for each mass candidate in the two processes are merged to differentiate masses and false positives (FPs). For detection on SFMs, we previously developed a dual system approach by fusing two single CAD systems optimized for detection of average and subtle masses, respectively. A trained neural network is used to merge the mass likelihood scores of the two single systems to reduce FPs. At the case-based sensitivities of 80% and 85%, mass detection in the DBT volume resulted in an average of 0.72 and 1.06 FPs/view, and detection in the SFMs yielded 0.94 and 1.67 FPs/view, respectively. The difference fell short of statistical significance (p=0.07) by JAFROC analysis. Study is underway to collect a larger data set and to further improve the DBT CAD system.

  16. Evaluation of digital breast tomosynthesis reconstruction algorithms using synchrotron radiation in standard geometry

    SciTech Connect

    Bliznakova, K.; Kolitsi, Z.; Speller, R. D.; Horrocks, J. A.; Tromba, G.; Pallikarakis, N.

    2010-04-15

    Purpose: In this article, the image quality of reconstructed volumes by four algorithms for digital tomosynthesis, applied in the case of breast, is investigated using synchrotron radiation. Methods: An angular data set of 21 images of a complex phantom with heterogeneous tissue-mimicking background was obtained using the SYRMEP beamline at ELETTRA Synchrotron Light Laboratory, Trieste, Italy. The irradiated part was reconstructed using the multiple projection algorithm (MPA) and the filtered backprojection with ramp followed by hamming windows (FBR-RH) and filtered backprojection with ramp (FBP-R). Additionally, an algorithm for reducing the noise in reconstructed planes based on noise mask subtraction from the planes of the originally reconstructed volume using MPA (MPA-NM) has been further developed. The reconstruction techniques were evaluated in terms of calculations and comparison of the contrast-to-noise ratio (CNR) and artifact spread function. Results: It was found that the MPA-NM resulted in higher CNR, comparable with the CNR of FBP-RH for high contrast details. Low contrast objects are well visualized and characterized by high CNR using the simple MPA and the MPA-NM. In addition, the image quality of the reconstructed features in terms of CNR and visual appearance as a function of the initial number of projection images and the reconstruction arc was carried out. Slices reconstructed with more input projection images result in less reconstruction artifacts and higher detail CNR, while those reconstructed from projection images acquired in reduced angular range causes pronounced streak artifacts. Conclusions: Of the reconstruction algorithms implemented, the MPA-NM and MPA are a good choice for detecting low contrast objects, while the FBP-RH, FBP-R, and MPA-NM provide high CNR and well outlined edges in case of microcalcifications.

  17. Digital breast tomosynthesis: computer-aided detection of clustered microcalcifications on planar projection images

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    This paper describes a new approach to detect microcalcification clusters (MCs) in digital breast tomosynthesis (DBT) via its planar projection (PPJ) image. With IRB approval, two-view (cranio-caudal and mediolateral oblique views) DBTs of human subject breasts were obtained with a GE GEN2 prototype DBT system that acquires 21 projection angles spanning 60° in 3° increments. A data set of 307 volumes (154 human subjects) was divided by case into independent training (127 with MCs) and test sets (104 with MCs and 76 free of MCs). A simultaneous algebraic reconstruction technique with multiscale bilateral filtering (MSBF) regularization was used to enhance microcalcifications and suppress noise. During the MSBF regularized reconstruction, the DBT volume was separated into high frequency (HF) and low frequency components representing microcalcifications and larger structures. At the final iteration, maximum intensity projection was applied to the regularized HF volume to generate a PPJ image that contained MCs with increased contrast-to-noise ratio (CNR) and reduced search space. High CNR objects in the PPJ image were extracted and labeled as microcalcification candidates. Convolution neural network trained to recognize the image pattern of microcalcifications was used to classify the candidates into true calcifications and tissue structures and artifacts. The remaining microcalcification candidates were grouped into MCs by dynamic conditional clustering based on adaptive CNR threshold and radial distance criteria. False positive (FP) clusters were further reduced using the number of candidates in a cluster, CNR and size of microcalcification candidates. At 85% sensitivity an FP rate of 0.71 and 0.54 was achieved for view- and case-based sensitivity, respectively, compared to 2.16 and 0.85 achieved in DBT. The improvement was significant (p-value = 0.003) by JAFROC analysis.

  18. False positive reduction of microcalcification cluster detection in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Xu, Ning; Yi, Sheng; Mendonca, Paulo; Tian, Tai-peng; Samala, Ravi; Chan, Heang-Ping

    2014-03-01

    Digital breast tomosynthesis (DBT) is a new modality that has strong potential in improving the sensitivity and specificity of breast mass detection. However, the detection of microcalcifications (MCs) in DBT is challenging because radiologists have to search for the often subtle signals in many slices. We are developing a computer-aided detection (CAD) system to assist radiologists in reading DBT. The system consists of four major steps, namely: image enhancement; pre-screening of MC candidates; false-positive (FP) reduction, and detection of MC cluster candidates of clinical interest. We propose an algorithm for reducing FPs by using 3D characteristics of MC clusters in DBT. The proposed method takes the MC candidates from the pre-screening step described in [14] as input, which are then iteratively clustered to provide training samples to a random-forest classifier and a rule-based classifier. The random forest classifier is used to learn a discriminative model of MC clusters using 3D texture features, whereas the rule-based classifier revisits the initial training samples and enhances them by combining median filtering and graph-cut-based segmentation followed by thresholding on the final number of MCs belonging to the candidate cluster. The outputs of these two classifiers are combined according to the prediction confidence of the random-forest classifier. We evaluate the proposed FP-reduction algorithm on a data set of two-view DBT from 40 breasts with biopsy-proven MC clusters. The experimental results demonstrate a significant reduction in FP detections, with a final sensitivity of 92.2% for an FP rate of 50%.

  19. Digital breast tomosynthesis: computer-aided detection of clustered microcalcifications on planar projection images.

    PubMed

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

    2014-12-01

    This paper describes a new approach to detect microcalcification clusters (MCs) in digital breast tomosynthesis (DBT) via its planar projection (PPJ) image. With IRB approval, two-view (cranio-caudal and mediolateral oblique views) DBTs of human subject breasts were obtained with a GE GEN2 prototype DBT system that acquires 21 projection angles spanning 60° in 3° increments. A data set of 307 volumes (154 human subjects) was divided by case into independent training (127 with MCs) and test sets (104 with MCs and 76 free of MCs). A simultaneous algebraic reconstruction technique with multiscale bilateral filtering (MSBF) regularization was used to enhance microcalcifications and suppress noise. During the MSBF regularized reconstruction, the DBT volume was separated into high frequency (HF) and low frequency components representing microcalcifications and larger structures. At the final iteration, maximum intensity projection was applied to the regularized HF volume to generate a PPJ image that contained MCs with increased contrast-to-noise ratio (CNR) and reduced search space. High CNR objects in the PPJ image were extracted and labeled as microcalcification candidates. Convolution neural network trained to recognize the image pattern of microcalcifications was used to classify the candidates into true calcifications and tissue structures and artifacts. The remaining microcalcification candidates were grouped into MCs by dynamic conditional clustering based on adaptive CNR threshold and radial distance criteria. False positive (FP) clusters were further reduced using the number of candidates in a cluster, CNR and size of microcalcification candidates. At 85% sensitivity an FP rate of 0.71 and 0.54 was achieved for view- and case-based sensitivity, respectively, compared to 2.16 and 0.85 achieved in DBT. The improvement was significant (p-value = 0.003) by JAFROC analysis. PMID:25393654

  20. Effect of acquisition parameters on digital breast tomosynthesis: Total angular range and number of projection views

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The purpose of this study was to investigate the effect of different acquisition parameters and to determine the optimal set of acquisition parameters of projection views (PVs) for the new developed digital breast tomosynthesis (DBT) system. The DBT imaging parameters were optimized using 32 different acquisition sets with six angular ranges (±5°, ±10°, ±13°, ±17°, ±21°, and ±25°) and eight projection views (5, 11, 15, 21, 25, 31, 41, and 51 prjections). In addition to the contrastto-noise ratio (CNR), the artifact spread function (ASF) was used to quantify the in-focus plane artifacts along the z-direction in order to explore the relationship between the acquisition parameters and the image quality. A commercially, available breast-mimicking phantom was imaged to qualitatively verify our results. Our results show that a wide angular range improved the reconstructed image quality in the z-direction. If a large number of projections are acquired, then the electronic noise may dominate the CNR due to reduce the radiation dose per projection. Although increasing angular range was found to improve the vertical resolution, due to greater effective breast thickness, the image quality of microcalcifications in the in-focus plane was also found not to be improved by increasing the noise. Therefore, potential trade-offs of these physical imaging properties must be considered to optimize the acquisition configuration of a DBT system. Our results suggest possible directions for further improvements in DBT systems for high quality imaging.

  1. A simple scatter correction method for dual energy contrast-enhanced digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Lu, Yihuan; Lau, Beverly; Hu, Yue-Houng; Zhao, Wei; Gindi, Gene

    2014-03-01

    Dual-Energy Contrast Enhanced Digital Breast Tomosynthesis (DE-CE-DBT) has the potential to deliver diagnostic information for vascularized breast pathology beyond that available from screening DBT. DE-CE-DBT involves a contrast (iodine) injection followed by a low energy (LE) and a high energy (HE) acquisitions. These undergo weighted subtraction then a reconstruction that ideally shows only the iodinated signal. Scatter in the projection data leads to "cupping" artifacts that can reduce the visibility and quantitative accuracy of the iodinated signal. The use of filtered backprojection (FBP) reconstruction ameliorates these types of artifacts, but the use of FBP precludes the advantages of iterative reconstructions. This motivates an effective and clinically practical scatter correction (SC) method for the projection data. We propose a simple SC method, applied at each acquisition angle. It uses scatter-only data at the edge of the image to interpolate a scatter estimate within the breast region. The interpolation has an approximately correct spatial profile but is quantitatively inaccurate. We further correct the interpolated scatter data with the aid of easily obtainable knowledge of SPR (scatter-to-primary ratio) at a single reference point. We validated the SC method using a CIRS breast phantom with iodine inserts. We evaluated its efficacy in terms of SDNR and iodine quantitative accuracy. We also applied our SC method to a patient DE-CE-DBT study and showed that the SC allowed detection of a previously confirmed tumor at the edge of the breast. The SC method is quick to use and may be useful in a clinical setting.

  2. Two complementary model observers to evaluate reconstructions of simulated micro-calcifications in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Michielsen, Koen; Zanca, Federica; Marshall, Nicholas; Bosmans, Hilde; Nuyts, Johan

    2013-03-01

    New imaging modalities need to be properly evaluated before being introduced in clinical practice. The gold standard is to perform clinical trials or dedicated clinical performance related observer experiments with experienced readers. Unfortunately this is not feasible during development or optimization of new reconstruction algorithms due to their many degrees of freedom. Our goal is to design a set of model observers to evaluate the performance of newly developed reconstruction methods on the assessment of micro-calcifications in digital breast tomosynthesis. In order to do so, the model observers need to evaluate both detection and classification of micro-calcifications. A channelized Hotelling observer was created for the detection task and a Hotelling observer working on an extracted feature vector was implemented for the classification task. These observers were evaluated on their ability to predict the results of human observers. Results from a previous observer study were used as reference to compare performance between human and model observers. This study evaluated detection of small micro-calcifications (100 { 200 _m) by a free search task in a power law filtered noise background and classification of two types of larger micro-calcifications (200 {600 _m) in the same background. Scores from the free search study were evaluated using the weighted JAFROC method and the classification scores were analyzed using the DBM MRMC method. The same analysis methods were applied to the model observer scores. Results of the detection model observer were related linearly with the human observer results with a correlation coefficient of 0.962. The correlation coefficient for the classification task was 0.959 with a power law non-linear regression.

  3. Digital breast tomosynthesis: Computer-aided detection of clustered microcalcifications on planar projection images

    PubMed Central

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

    2014-01-01

    This paper describes a new approach to detection of microcalcification clusters (MCs) in digital breast tomosynthesis (DBT) via its planar projection (PPJ) image. With IRB approval, two-view (cranio-caudal and mediolateral oblique views) DBTs of human subject breasts were obtained with a GE GEN2 prototype DBT system that acquires 21 projection angles spanning 600 in 30 increments. A data set of 307 volumes (154 human subjects) was divided by case into independent training (127 with MCs) and test sets (104 with MCs and 76 free of MCs). Simultaneous algebraic reconstruction technique with multiscale bilateral filtering (MSBF) regularization was used to enhance microcalcifications and suppress noise. During the MSBF regularized reconstruction, the DBT volume was separated into high frequency (HF) and low frequency components representing microcalcifications and larger structures. At the final iteration, maximum intensity projection was applied to the regularized HF volume to generate a PPJ image that contained MCs with increased contrast-to-noise ratio (CNR) and reduced search space. High CNR objects in the PPJ image were extracted and labeled as microcalcification candidates. Convolution neural network (CNN) trained to recognize the image pattern of microcalcifications was used to classify the candidates into true calcifications and tissue structures and artifacts. The remaining microcalcification candidates were grouped into MCs by dynamic conditional clustering based on adaptive CNR threshold and radial distance criteria. False positive (FP) clusters were further reduced using the number of candidates in a cluster, CNR and size of microcalcification candidates. At 85% sensitivity an FP rate of 0.71 and 0.54 was achieved for view- and case-based sensitivity, respectively, compared to 2.16 and 0.85 achieved in DBT. The improvement was significant (p-value = 0.003) by JAFROC analysis. PMID:25393654

  4. A diffusion-based truncated projection artifact reduction method for iterative digital breast tomosynthesis reconstruction

    NASA Astrophysics Data System (ADS)

    Lu, Yao; Chan, Heang-Ping; Wei, Jun; Hadjiiski, Lubomir M.

    2013-02-01

    Digital breast tomosynthesis (DBT) has strong promise to improve sensitivity for detecting breast cancer. DBT reconstruction estimates the breast tissue attenuation using projection views (PVs) acquired in a limited angular range. Because of the limited field of view (FOV) of the detector, the PVs may not completely cover the breast in the x-ray source motion direction at large projection angles. The voxels in the imaged volume cannot be updated when they are outside the FOV, thus causing a discontinuity in intensity across the FOV boundaries in the reconstructed slices, which we refer to as the truncated projection artifact (TPA). Most existing TPA reduction methods were developed for the filtered backprojection method in the context of computed tomography. In this study, we developed a new diffusion-based method to reduce TPAs during DBT reconstruction using the simultaneous algebraic reconstruction technique (SART). Our TPA reduction method compensates for the discontinuity in background intensity outside the FOV of the current PV after each PV updating in SART. The difference in voxel values across the FOV boundary is smoothly diffused to the region beyond the FOV of the current PV. Diffusion-based background intensity estimation is performed iteratively to avoid structured artifacts. The method is applicable to TPA in both the forward and backward directions of the PVs and for any number of iterations during reconstruction. The effectiveness of the new method was evaluated by comparing the visual quality of the reconstructed slices and the measured discontinuities across the TPA with and without artifact correction at various iterations. The results demonstrated that the diffusion-based intensity compensation method reduced the TPA while preserving the detailed tissue structures. The visibility of breast lesions obscured by the TPA was improved after artifact reduction.

  5. A diffusion-based truncated projection artifact reduction method for iterative digital breast tomosynthesis reconstruction.

    PubMed

    Lu, Yao; Chan, Heang-Ping; Wei, Jun; Hadjiiski, Lubomir M

    2013-02-01

    Digital breast tomosynthesis (DBT) has strong promise to improve sensitivity for detecting breast cancer. DBT reconstruction estimates the breast tissue attenuation using projection views (PVs) acquired in a limited angular range. Because of the limited field of view (FOV) of the detector, the PVs may not completely cover the breast in the x-ray source motion direction at large projection angles. The voxels in the imaged volume cannot be updated when they are outside the FOV, thus causing a discontinuity in intensity across the FOV boundaries in the reconstructed slices, which we refer to as the truncated projection artifact (TPA). Most existing TPA reduction methods were developed for the filtered backprojection method in the context of computed tomography. In this study, we developed a new diffusion-based method to reduce TPAs during DBT reconstruction using the simultaneous algebraic reconstruction technique (SART). Our TPA reduction method compensates for the discontinuity in background intensity outside the FOV of the current PV after each PV updating in SART. The difference in voxel values across the FOV boundary is smoothly diffused to the region beyond the FOV of the current PV. Diffusion-based background intensity estimation is performed iteratively to avoid structured artifacts. The method is applicable to TPA in both the forward and backward directions of the PVs and for any number of iterations during reconstruction. The effectiveness of the new method was evaluated by comparing the visual quality of the reconstructed slices and the measured discontinuities across the TPA with and without artifact correction at various iterations. The results demonstrated that the diffusion-based intensity compensation method reduced the TPA while preserving the detailed tissue structures. The visibility of breast lesions obscured by the TPA was improved after artifact reduction. PMID:23318346

  6. Feasibility study of the diagnosis and monitoring of cystic fibrosis in pediatric patients using stationary digital chest tomosynthesis

    NASA Astrophysics Data System (ADS)

    Potuzko, Marci; Shan, Jing; Pearce, Caleb; Lee, Yueh Z.; Lu, Jianping; Zhou, Otto

    2015-03-01

    Digital chest tomosynthesis (DCT) is a 3D imaging modality which has been shown to approach the diagnostic capability of CT, but uses only one-tenth the radiation dose of CT. One limitation of current commercial DCT is the mechanical motion of the x-ray source which prolongs image acquisition time and introduces motion blurring in images. By using a carbon nanotube (CNT) x-ray source array, we have developed a stationary digital chest tomosynthesis (s- DCT) system which can acquire tomosynthesis images without mechanical motion, thus enhancing the image quality. The low dose and high quality 3D image makes the s-DCT system a viable imaging tool for monitoring cystic fibrosis (CF) patients. The low dose is especially important in pediatric patients who are both more radiosensitive and have a longer lifespan for radiation symptoms to develop. The purpose of this research is to evaluate the feasibility of using s-DCT as a faster, lower dose means for diagnosis and monitoring of CF in pediatric patients. We have created an imaging phantom by injecting a gelatinous mucus substitute into porcine lungs and imaging the lungs from within an anthropomorphic hollow chest phantom in order to mimic the human conditions of a CF patient in the laboratory setting. We have found that our s-DCT images show evidence of mucus plugging in the lungs and provide a clear picture of the airways in the lung, allowing for the possibility of using s- DCT to supplement or replace CT as the imaging modality for CF patients.

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

    SciTech Connect

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

    2005-09-15

    Automatic exposure control (AEC) is an important feature in mammography. It enables consistently optimal image exposure despite variations in tissue density and thickness, and user skill level. Full field digital mammography systems cannot employ conventional AEC methods because digital receptors fully absorb the x-ray beam. In this paper we describe an AEC procedure for slot scanning mammography. With slot scanning detectors, our approach uses a fast low-resolution and low-exposure prescan to acquire an image of the breast. Tube potential depends on breast thickness, and the prescan histogram provides the necessary information to calculate the required tube current. We validate our approach with simulated prescan images and phantom measurements. We achieve accurate exposure tracking with thickness and density, and expect this method of AEC to reduce retakes and improve workflow.

  8. Image quality of microcalcifications in digital breast tomosynthesis: Effects of projection-view distributions

    SciTech Connect

    Lu, Yao; Chan, Heang-Ping; Wei, Jun; Goodsitt, Mitch; Carson, Paul L.; Hadjiiski, Lubomir; Schmitz, Andrea; Eberhard, Jeffrey W.; Claus, Bernhard E. H.

    2011-10-15

    Purpose: To analyze the effects of projection-view (PV) distribution on the contrast and spatial blurring of microcalcifications on the tomosynthesized slices (X-Y plane) and along the depth (Z) direction for the same radiation dose in digital breast tomosynthesis (DBT). Methods: A GE GEN2 prototype DBT system was used for acquisition of DBT scans. The system acquires PV images from 21 angles in 3 deg. increments over a {+-}30 deg. range. From these acquired PV images, the authors selected six subsets of PV images to simulate DBT of different angular ranges and angular increments. The number of PV images in each subset was fixed at 11 to simulate a constant total dose. These different PV distributions were subjectively divided into three categories: uniform group, nonuniform central group, and nonuniform extreme group with different angular ranges and angular increments. The simultaneous algebraic reconstruction technique (SART) was applied to each subset to reconstruct the DBT slices. A selective diffusion regularization method was employed to suppress noise. The image quality of microcalcifications in the reconstructed DBTs with different PV distributions was compared using the DBT scans of an American College of Radiology phantom and three human subjects. The contrast-to-noise ratio (CNR) and the full width at half maximum (FWHM) of the line profiles of microcalcifications within their in-focus DBT slices (parallel to detector plane) and the FWHMs of the interplane artifact spread function (ASF) in the Z-direction (perpendicular to detector plane) were used as image quality measures. Results: The results indicate that DBT acquired with a large angular range or, for an equal angular range,with a large fraction of PVs at large angles yielded superior ASF with smaller FWHM in the Z-direction. PV distributions with a narrow angular range or a large fraction of PVs at small angles had stronger interplane artifacts. In the X-Y focal planes, the effect of PV

  9. A software tool of digital tomosynthesis application for patient positioning in radiotherapy.

    PubMed

    Yan, Hui; Dai, Jian-Rong

    2016-01-01

    Digital Tomosynthesis (DTS) is an image modality in reconstructing tomographic images from two-dimensional kV projections covering a narrow scan angles. Comparing with conventional cone-beam CT (CBCT), it requires less time and radiation dose in data acquisition. It is feasible to apply this technique in patient positioning in radiotherapy. To facilitate its clinical application, a software tool was developed and the reconstruction processes were accelerated by graphic process-ing unit (GPU). Two reconstruction and two registration processes are required for DTS application which is different from conventional CBCT application which requires one image reconstruction process and one image registration process. The reconstruction stage consists of productions of two types of DTS. One type of DTS is reconstructed from cone-beam (CB) projections covering a narrow scan angle and is named onboard DTS (ODTS), which represents the real patient position in treatment room. Another type of DTS is reconstructed from digitally reconstructed radiography (DRR) and is named reference DTS (RDTS), which represents the ideal patient position in treatment room. Prior to the reconstruction of RDTS, The DRRs are reconstructed from planning CT using the same acquisition setting of CB projections. The registration stage consists of two matching processes between ODTS and RDTS. The target shift in lateral and longitudinal axes are obtained from the matching between ODTS and RDTS in coronal view, while the target shift in longitudinal and vertical axes are obtained from the matching between ODTS and RDTS in sagittal view. In this software, both DRR and DTS reconstruction algorithms were implemented on GPU environments for acceleration purpose. The comprehensive evaluation of this software tool was performed including geometric accuracy, image quality, registration accuracy, and reconstruction efficiency. The average correlation coefficient between DRR/DTS generated by GPU-based algorithm

  10. Selective-diffusion regularization for enhancement of microcalcifications in digital breast tomosynthesis reconstruction

    SciTech Connect

    Lu Yao; Chan, Heang-Ping; Wei Jun; Hadjiiski, Lubomir M.

    2010-11-15

    Purpose: Digital breast tomosynthesis (DBT) has been shown to improve mass detection. Detection of microcalcifications is more challenging because of the large breast volume to be searched for subtle signals. The simultaneous algebraic reconstruction technique (SART) was found to provide good image quality for DBT, but the image noise is amplified with an increasing number of iterations. In this study, the authors developed a selective-diffusion (SD) method for noise regularization with SART to improve the contrast-to-noise ratio (CNR) of microcalcifications in the DBT slices for human or machine detection. Methods: The SD method regularizes SART reconstruction during updating with each projection view. Potential microcalcifications are differentiated from the noisy background by estimating the local gradient information. Different degrees of regularization are applied to the signal or noise classes, such that the microcalcifications will be enhanced while the noise is suppressed. The new SD method was compared to several current methods, including the quadratic Laplacian (QL) method, the total variation (TV) method, and the nonconvex total p-variation (TpV) method for noise regularization with SART. A GE GEN2 prototype DBT system with a stationary digital detector was used for the acquisition of DBT scans at 21 angles in 3 deg. increments over a {+-}30 deg. range. The reconstruction image quality without regularization and that with the different regularization methods were compared using the DBT scans of an American College of Radiology phantom and a human subject. The CNR and the full width at half maximum (FWHM) of the line profiles of microcalcifications within the in-focus DBT slices were used as image quality measures. Results: For the comparison of large microcalcifications in the DBT data of the subject, the SD method resulted in comparable CNR to the nonconvex TpV method. Both of them performed better than the other two methods. For subtle

  11. Applying high frame-rate digital radiography and dual-energy distributed-sources for advanced tomosynthesis

    NASA Astrophysics Data System (ADS)

    Travish, Gil; Rangel, Felix J.; Evans, Mark A.; Schmiedehausen, Kristin

    2013-09-01

    Conventional radiography uses a single point x-ray source with a fan or cone beam to visualize various areas of the human body. An imager records the transmitted photons—historically film and now increasingly digital radiography (DR) flat panel detectors—followed by optional image post-processing. Some post-processing techniques of particular interest are tomosynthesis, and dual energy subtraction. Tomosynthesis adds the ability to recreate quasi-3D images from a series of 2D projections. These exposures are typically taken along an arc or other path; and, tomosynthesis reconstruction is used to form a three-dimensional representation of the area of interest. Dual-energy radiography adds the ability to enhance or "eliminate" structures based on their different attenuation of well-separated end-point energies in two exposures. These advanced capabilities come at a high cost in terms of complexity, imaging time, capital equipment, space, and potentially reduced image quality due to motion blur if acquired sequentially. Recently, the prospect of creating x-ray sources, which are composed of arrays of micro-emitters, has been put forward. These arrays offer a flat-panel geometry and may afford advantages in fabrication methodology, size and cost. They also facilitate the use of the dual energy technology. Here we examine the possibility of using such an array of x-ray sources combined with high frame-rate (~kHz) DR detectors to produce advanced medical images without the need for moving gantries or other complex motion systems. Combining the advantages of dual energy imaging with the ability to determine the relative depth location of anatomical structures or pathological findings from imaging procedures should prove to be a powerful diagnostic tool. We also present use cases that would benefit from the capabilities of this modality.

  12. Task-based performance analysis of SART for digital breast tomosynthesis using signal CNR and channelised Hotelling observers

    NASA Astrophysics Data System (ADS)

    Van de Sompel, Dominique; Brady, Michael; Ho, Candy P. S.; McLennan, Andrew

    2010-04-01

    In this study, we examine the performance of the simultaneous algebraic reconstruction technique (SART) for digital breast tomosynthesis under variations in key imaging parameters, such as the number of iterations, number of projections, angular range, initial guess, radiation dose, etc. We use a real breast CT volume as a ground truth digital phantom from which to simulate x-ray projections under the various selected conditions. The reconstructed image quality is measured using task-based metrics, namely signal CNR and the AUC of a Channelised Hotelling Observer with Laguerre-Gauss basis functions. The task at hand is a signal-known-exactly (SKE) task, where the objective is to detect a simulated mass inserted into the breast CT volume.

  13. Synchrotron based planar imaging and digital tomosynthesis of breast and biopsy phantoms using a CMOS active pixel sensor.

    PubMed

    Szafraniec, Magdalena B; Konstantinidis, Anastasios C; Tromba, Giuliana; Dreossi, Diego; Vecchio, Sara; Rigon, Luigi; Sodini, Nicola; Naday, Steve; Gunn, Spencer; McArthur, Alan; Olivo, Alessandro

    2015-03-01

    The SYRMEP (SYnchrotron Radiation for MEdical Physics) beamline at Elettra is performing the first mammography study on human patients using free-space propagation phase contrast imaging. The stricter spatial resolution requirements of this method currently force the use of conventional films or specialized computed radiography (CR) systems. This also prevents the implementation of three-dimensional (3D) approaches. This paper explores the use of an X-ray detector based on complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology as a possible alternative, for acquisitions both in planar and tomosynthesis geometry. Results indicate higher quality of the images acquired with the synchrotron set-up in both geometries. This improvement can be partly ascribed to the use of parallel, collimated and monochromatic synchrotron radiation (resulting in scatter rejection, no penumbra-induced blurring and optimized X-ray energy), and partly to phase contrast effects. Even though the pixel size of the used detector is still too large - and thus suboptimal - for free-space propagation phase contrast imaging, a degree of phase-induced edge enhancement can clearly be observed in the images. PMID:25498332

  14. Intrafractional 3D localization using kilovoltage digital tomosynthesis for sliding-window intensity modulated radiation therapy.

    PubMed

    Zhang, Pengpeng; Hunt, Margie; Pham, Hai; Tang, Grace; Mageras, Gig

    2015-09-01

    To implement novel imaging sequences integrated into intensity modulated radiation therapy (IMRT) and determine 3D positions for intrafractional patient motion monitoring and management.In one method, we converted a static gantry IMRT beam into a series of arcs in which dose index and multileaf collimator positions for all control points were unchanged, but gantry angles were modified to oscillate ± 3° around the original angle. Kilovoltage (kV) projections were acquired continuously throughout delivery and reconstructed to provide a series of 6° arc digital tomosynthesis (DTS) images which served to evaluate the in-plane positions of embedded-fiducials/vertebral-body. To obtain out-of-plane positions via triangulation, a 20° gantry rotation with beam hold-off was inserted during delivery to produce a pair of 6° DTS images separated by 14°. In a second method, the gantry remained stationary, but both kV source and detector moved over a 15° longitudinal arc using pitch and translational adjustment of the robotic arms. Evaluation of localization accuracy in an anthropomorphic Rando phantom during simulated intrafractional motion used programmed couch translations from customized scripts. Purpose-built software was used to reconstruct DTS images, register them to reference template images and calculate 3D fiducial positions.No significant dose difference (<0.5%) was found between the original and converted IMRT beams. For a typical hypofractionated spine treatment, 200 single DTS (6° arc) and 10 paired DTS (20° arc) images were acquired for each IMRT beam, providing in-plane and out-of-plane monitoring every 1.6 and 34.5 s, respectively. Mean ± standard deviation error in predicted position was -0.3 ± 0.2 mm, -0.1 ± 0.1 mm in-plane, and 0.2 ± 0.4 mm out-of-plane with rotational gantry, 0.8 ± 0.1 mm, -0.7 ± 0.3 mm in-plane and 1.1 ± 0.1 mm out-of-plane with translational source/detector.Acquiring 3D fiducial positions from kV-DTS during fixed gantry

  15. A scatter correction method for contrast-enhanced dual-energy digital breast tomosynthesis.

    PubMed

    Lu, Yihuan; Peng, Boyu; Lau, Beverly A; Hu, Yue-Houng; Scaduto, David A; Zhao, Wei; Gindi, Gene

    2015-08-21

    Contrast-enhanced dual energy digital breast tomosynthesis (CE-DE-DBT) is designed to image iodinated masses while suppressing breast anatomical background. Scatter is a problem, especially for high energy acquisition, in that it causes severe cupping artifact and iodine quantitation errors. We propose a patient specific scatter correction (SC) algorithm for CE-DE-DBT. The empirical algorithm works by interpolating scatter data outside the breast shadow into an estimate within the breast shadow. The interpolated estimate is further improved by operations that use an easily obtainable (from phantoms) table of scatter-to-primary-ratios (SPR)--a single SPR value for each breast thickness and acquisition angle. We validated our SC algorithm for two breast emulating phantoms by comparing SPR from our SC algorithm to that measured using a beam-passing pinhole array plate. The error in our SC computed SPR, averaged over acquisition angle and image location, was about 5%, with slightly worse errors for thicker phantoms. The SC projection data, reconstructed using OS-SART, showed a large degree of decupping. We also observed that SC removed the dependence of iodine quantitation on phantom thickness. We applied the SC algorithm to a CE-DE-mammographic patient image with a biopsy confirmed tumor at the breast periphery. In the image without SC, the contrast enhanced tumor was masked by the cupping artifact. With our SC, the tumor was easily visible. An interpolation-based SC was proposed by (Siewerdsen et al 2006 Med. Phys. 33 187-97) for cone-beam CT (CBCT), but our algorithm and application differ in several respects. Other relevant SC techniques include Monte-Carlo and convolution-based methods for CBCT, storage of a precomputed library of scatter maps for DBT, and patient acquisition with a beam-passing pinhole array for breast CT. Our SC algorithm can be accomplished in clinically acceptable times, requires no additional imaging hardware or extra patient dose and is

  16. Automatic registration between reference and on-board digital tomosynthesis images for positioning verification.

    PubMed

    Ren, Lei; Godfrey, Devon J; Yan, Hui; Wu, Q Jackie; Yin, Fang-Fang

    2008-02-01

    The authors developed a hybrid multiresolution rigid-body registration technique to automatically register reference digital tomosynthesis (DTS) images with on-board DTS images to guide patient positioning in radiation therapy. This hybrid registration technique uses a faster but less accurate static method to achieve an initial registration, followed by a slower but more accurate adaptive method to fine tune the registration. A multiresolution scheme is employed in the registration to further improve the registration accuracy, robustness, and efficiency. Normalized mutual information is selected as the criterion for the similarity measure and the downhill simplex method is used as the search engine. This technique was tested using image data both from an anthropomorphic chest phantom and from eight head-and-neck cancer patients. The effects of the scan angle and the region-of-interest (ROI) size on the registration accuracy and robustness were investigated. The necessity of using the adaptive registration method in the hybrid technique was validated by comparing the results of the static method and the hybrid method. With a 44 degrees scan angle and a large ROI covering the entire DTS volume, the average of the registration capture ranges in single-axis simulations was between -31 and +34 deg for rotations and between -89 and +78 mm for translations in the phantom study, and between -38 and +38 deg for rotations and between -58 and +65 mm for translations in the patient study. Decreasing the DTS scan angle from 44 degrees to 22 degrees mainly degraded the registration accuracy and robustness for the out-of-plane rotations. Decreasing the ROI size from the entire DTS volume to the volume surrounding the spinal cord reduced the capture ranges to between -23 and +18 deg for rotations and between -33 and +43 mm for translations in the phantom study, and between -18 and +25 deg for rotations and between -35 and +39 mm for translations in the patient study. Results also

  17. A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map

    SciTech Connect

    Ren Lei; Zhang Junan; Thongphiew, Danthai; Godfrey, Devon J.; Jackie Wu, Q.; Zhou Sumin; Yin Fangfang

    2008-07-15

    We developed a novel digital tomosynthesis (DTS) reconstruction method using a deformation field map to optimally estimate volumetric information in DTS images. The deformation field map is solved by using prior information, a deformation model, and new projection data. Patients' previous cone-beam CT (CBCT) or planning CT data are used as the prior information, and the new patient volume to be reconstructed is considered as a deformation of the prior patient volume. The deformation field is solved by minimizing bending energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. The new patient DTS volume is then obtained by deforming the prior patient CBCT or CT volume according to the solution to the deformation field. This method is novel because it is the first method to combine deformable registration with limited angle image reconstruction. The method was tested in 2D cases using simulated projections of a Shepp-Logan phantom, liver, and head-and-neck patient data. The accuracy of the reconstruction was evaluated by comparing both organ volume and pixel value differences between DTS and CBCT images. In the Shepp-Logan phantom study, the reconstructed pixel signal-to-noise ratio (PSNR) for the 60 deg. DTS image reached 34.3 dB. In the liver patient study, the relative error of the liver volume reconstructed using 60 deg. projections was 3.4%. The reconstructed PSNR for the 60 deg. DTS image reached 23.5 dB. In the head-and-neck patient study, the new method using 60 deg. projections was able to reconstruct the 8.1 deg. rotation of the bony structure with 0.0 deg. error. The reconstructed PSNR for the 60 deg. DTS image reached 24.2 dB. In summary, the new reconstruction method can optimally estimate the volumetric information in DTS images using 60 deg. projections. Preliminary validation of the algorithm showed that it is both technically and clinically feasible for image guidance in radiation therapy.

  18. Automatic registration between reference and on-board digital tomosynthesis images for positioning verification

    SciTech Connect

    Ren Lei; Godfrey, Devon J.; Yan, Hui; Wu, Q. Jackie; Yin, Fang-Fang

    2008-02-15

    The authors developed a hybrid multiresolution rigid-body registration technique to automatically register reference digital tomosynthesis (DTS) images with on-board DTS images to guide patient positioning in radiation therapy. This hybrid registration technique uses a faster but less accurate static method to achieve an initial registration, followed by a slower but more accurate adaptive method to fine tune the registration. A multiresolution scheme is employed in the registration to further improve the registration accuracy, robustness, and efficiency. Normalized mutual information is selected as the criterion for the similarity measure and the downhill simplex method is used as the search engine. This technique was tested using image data both from an anthropomorphic chest phantom and from eight head-and-neck cancer patients. The effects of the scan angle and the region-of-interest (ROI) size on the registration accuracy and robustness were investigated. The necessity of using the adaptive registration method in the hybrid technique was validated by comparing the results of the static method and the hybrid method. With a 44 deg. scan angle and a large ROI covering the entire DTS volume, the average of the registration capture ranges in single-axis simulations was between -31 and +34 deg. for rotations and between -89 and +78 mm for translations in the phantom study, and between -38 and +38 deg. for rotations and between -58 and +65 mm for translations in the patient study. Decreasing the DTS scan angle from 44 deg. to 22 deg. mainly degraded the registration accuracy and robustness for the out-of-plane rotations. Decreasing the ROI size from the entire DTS volume to the volume surrounding the spinal cord reduced the capture ranges to between -23 and +18 deg. for rotations and between -33 and +43 mm for translations in the phantom study, and between -18 and +25 deg. for rotations and between -35 and +39 mm for translations in the patient study. Results also

  19. Multiscale bilateral filtering for improving image quality in digital breast tomosynthesis

    PubMed Central

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

    2015-01-01

    Purpose: Detection of subtle microcalcifications in digital breast tomosynthesis (DBT) is a challenging task because of the large, noisy DBT volume. It is important to enhance the contrast-to-noise ratio (CNR) of microcalcifications in DBT reconstruction. Most regularization methods depend on local gradient and may treat the ill-defined margins or subtle spiculations of masses and subtle microcalcifications as noise because of their small gradient. The authors developed a new multiscale bilateral filtering (MSBF) regularization method for the simultaneous algebraic reconstruction technique (SART) to improve the CNR of microcalcifications without compromising the quality of masses. Methods: The MSBF exploits a multiscale structure of DBT images to suppress noise and selectively enhance high frequency structures. At the end of each SART iteration, every DBT slice is decomposed into several frequency bands via Laplacian pyramid decomposition. No regularization is applied to the low frequency bands so that subtle edges of masses and structured background are preserved. Bilateral filtering is applied to the high frequency bands to enhance microcalcifications while suppressing noise. The regularized DBT images are used for updating in the next SART iteration. The new MSBF method was compared with the nonconvex total p-variation (TpV) method for noise regularization with SART. A GE GEN2 prototype DBT system was used for acquisition of projections at 21 angles in 3° increments over a ±30° range. The reconstruction image quality with no regularization (NR) and that with the two regularization methods were compared using the DBT scans of a heterogeneous breast phantom and several human subjects with masses and microcalcifications. The CNR and the full width at half maximum (FWHM) of the line profiles of microcalcifications and across the spiculations within their in-focus DBT slices were used as image quality measures. Results: The MSBF method reduced contouring artifacts

  20. Evaluation of low contrast detectability after scatter correction in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Michielsen, Koen; Fieselmann, Andreas; Cockmartin, Lesley; Nuyts, Johan

    2014-03-01

    Projection images from digital breast tomosynthesis acquisitions can contain a large fraction of scattered x-rays due to the absence of an anti-scatter grid in front of the detector. In order to produce quantitative results, this should be accounted for in reconstruction algorithms. We examine the possible improvement in signal difference to noise ratio (SDNR) for low contrast spherical densities when applying a scatter correction algorithm. Hybrid patient data were created by combining real patient data with attenuation profiles of spherical masses acquired with matching exposure settings. Scatter in these cases was estimated using Monte-Carlo based scatter- ing kernels. All cases were reconstructed using filtered backprojection (FBP) with and without beam hardening correction and two maximum likelihood methods for transmission tomography, with and without quadratic smoothing prior (MAPTR and MLTR). For all methods, images were reconstructed without scatter correction, and with scatter precorrection, and for the iterative methods also with an adjusted update step obtained by including scatter in the physics model. SDNR of the inserted spheres was calculated by subtracting the recon- structions with and without inserted template to measure the signal difference, while noise was measured in the image containing the template. SDNR was significantly improved by 3.5% to 4.5% (p < 0.0001) at iteration 10 for both correction methods applied to the MLTR and MAPTR reconstructions. For MLTR these differences disappeared by iteration 100. For regular FBP SDNR remained the same after correction (p = 0.60) while it dropped slightly for FBP with beam hardening correction (-1.4%, p = 0.028). These results indicate that for the iterative methods, application of a scatter correction algorithm has very little effect on the SDNR, it only causes a slight decrease in convergence speed, which is similar for precorrection and correction incorporated in the update step. The FBP results

  1. Four Dimensional Digital Tomosynthesis Using on-Board Imager for the Verification of Respiratory Motion

    PubMed Central

    Park, Justin C.; Kim, Jin Sung; Park, Sung Ho; Webster, Matthew J.; Lee, Soyoung; Song, William Y.; Han, Youngyih

    2014-01-01

    Purpose To evaluate respiratory motion of a patient by generating four-dimensional digital tomosynthesis (4D DTS), extracting respiratory signal from patients' on-board projection data, and ensuring the feasibility of 4D DTS as a localization tool for the targets which have respiratory movement. Methods and Materials Four patients with lung and liver cancer were included to verify the feasibility of 4D-DTS with an on-board imager. CBCT acquisition (650–670 projections) was used to reconstruct 4D DTS images and the breath signal of the patients was generated by extracting the motion of diaphragm during data acquisition. Based on the extracted signal, the projection data was divided into four phases: peak-exhale phase, mid-inhale phase, peak-inhale phase, and mid-exhale phase. The binned projection data was then used to generate 4D DTS, where the total scan angle was assigned as ±22.5° from rotation center, centered on 0° and 180° for coronal “half-fan” 4D DTS, and 90° and 270° for sagittal “half-fan” 4D DTS. The result was then compared with 4D CBCT which we have also generated with the same phase distribution. Results The motion of the diaphragm was evident from the 4D DTS results for peak-exhale, mid-inhale, peak-inhale and mid-exhale phase assignment which was absent in 3D DTS. Compared to the result of 4D CBCT, the view aliasing effect due to arbitrary angle reconstruction was less severe. In addition, the severity of metal artifacts, the image distortion due to presence of metal, was less than that of the 4D CBCT results. Conclusion We have implemented on-board 4D DTS on patients data to visualize the movement of anatomy due to respiratory motion. The results indicate that 4D-DTS could be a promising alternative to 4D CBCT for acquiring the respiratory motion of internal organs just prior to radiotherapy treatment. PMID:25541710

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

    SciTech Connect

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

    2015-07-15

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

  3. Applications of matrix inversion tomosynthesis

    NASA Astrophysics Data System (ADS)

    Warp, Richard J.; Godfrey, Devon J.; Dobbins, James T., III

    2000-04-01

    The improved image quality and characteristics of new flat- panel x-ray detectors have renewed interest in advanced algorithms such as tomosynthesis. Digital tomosynthesis is a method of acquiring and reconstructing a three-dimensional data set with limited-angle tube movement. Historically, conventional tomosynthesis reconstruction has suffered contamination of the planes of interest by blurred out-of- plane structures. This paper focuses on a Matrix Inversion Tomosynthesis (MITS) algorithm to remove unwanted blur from adjacent planes. The algorithm uses a set of coupled equations to solve for the blurring function in each reconstructed plane. This paper demonstrates the use of the MITS algorithm in three imaging applications: small animal microscopy, chest radiography, and orthopedics. The results of the MITS reconstruction process demonstrate an improved reduction of blur from out-of-plane structures when compared to conventional tomosynthesis. We conclude that the MITS algorithm holds potential in a variety of applications to improve three-dimensional image reconstruction.

  4. Evaluation of a photon-counting breast tomosynthesis imaging system

    NASA Astrophysics Data System (ADS)

    Maidment, Andrew D. A.; Ullberg, Christer; Lindman, Karin; Adelöw, Leif; Egerström, Johan; Eklund, Mathias; Francke, Tom; Jordung, Ulf; Kristoffersson, Tomas; Lindqvist, Lars; Marchal, Daniel; Olla, Hans; Penton, Erik; Rantanen, Juha; Solokov, Skiff; Weber, Niclas; Westerberg, Hans

    2006-03-01

    Digital breast tomosynthesis promises solutions to many of the problems associated with projection mammography, including elimination of artifactual densities due to the superposition of normal tissues and increasing the conspicuity of true lesions that would otherwise be masked by superimposed normal tissue. We have investigated tomosynthesis using a digital camera containing 48 photon counting, orientation sensitive, linear detectors which are precisely aligned with the focal spot of the x-ray source. The x-ray source and the digital detectors are scanned in a continuous motion across the object (patient), each linear detector collecting an image at a distinct angle. A preliminary assessment of tomosynthesis image quality has been performed with both qualitative and quantitative methods. Measured values of MTF and NPS appear concordant with theoretical values. The MTF in the scanning direction is dominated by scanning unsharpness and geometric factors, while the NPS is white. The MTF and NPS in the strip direction are somewhat lower than in the scan direction. The NPS of tomographic images show a slight decrease with increasing spatial frequency, related to the sampling and interpolation in the reconstruction process. A phase I clinical trial is ongoing; 9 women have been recruited. Breast positioning is comparable to other imaging systems. The visualization of breast anatomy appears to be superior to screen-film mammography, at the same average glandular dose. Examination of images reconstructed with a sub-sampled set of projection images appears to support the hypothesis that image quality is superior when more projection images are used in the reconstruction.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2015-11-01

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

  7. Digital tomosynthesis (DTS) for verification of target position in early stage lung cancer patients

    SciTech Connect

    Sörnsen de Koste, John R. van; Dahele, Max; Senan, Suresh; Weide, Lineke van der; Slotman, Ben J.; Verbakel, Wilko F. A. R.; Mostafavi, Hassan

    2013-09-15

    Purpose: The ability to verify intrafraction tumor position is clinically useful for hypofractionated treatments. Short arc kV digital tomosynthesis (DTS) could facilitate more frequent target verification. The authors used DTS combined with triangulation to determine the mean temporal position of small-volume lung tumor targets treated with stereotactic radiotherapy. DTS registration results were benchmarked against online clinical localization using registration between free-breathing cone-beam computed tomography (CBCT) and the average intensity projection (AvIP) of the planning 4DCT.Methods: In this retrospective study, 76 sets of kV-projection images from online CBCT scans of 13 patients were used to generate DTS image slices (CB-DTS) with nonclinical research software (DTS Toolkit, Varian Medical Systems). Three-dimensional tumor motion was 1.3–4 mm in six patients and 6.1–25.4 mm in seven patients on 4DCT (significant difference in the mean of the groups, P < 0.01). The 4DCT AvIP was used to digitally reconstruct the Reference-DTS. DTS registration and DTS registration combined with triangulation were investigated. Progressive shortening of total DTS arc lengths from 95° to 35° around 0° gantry position was evaluated for different scenarios: DTS registration using the entire arc; DTS registration plus triangulation using two nonoverlapping arcs; and for 55° and 45° total gantry rotation, DTS registration plus triangulation using two overlapping arcs. Finally, DTS registration plus triangulation performed at eight gantry angles, each separated by 45° was evaluated using full fan kV projection data for one patient with an immobile tumor and five patients with mobile tumors.Results: For DTS registration alone, shortening arc length did not influence accuracy in X- and Y-directions, but in Z-direction, mean deviations from online CBCT localization systematically increased for shorter arc length (P < 0.05). For example, using a 95° arc mean DTS

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

    PubMed

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

    2016-07-01

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

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

    SciTech Connect

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

    2008-08-11

    This work deals with the application of the contrast-medium-enhanced digital subtraction mammography technique in order to calibrate the contrast level in subtracted phantom images as function of iodine concentration to perform dynamic studies of the contrast-medium uptake in the breast. Previously optimized dual-energy temporal subtraction modalities were used (a) to determine radiological parameters for a dynamic clinical study composed of 1 mask+3 post-contrast images limiting the total mean glandular dose to 2.5 mGy, and (b) to perform a contrast vs iodine concentration calibration using a custom-made phantom. Calculated exposure values were applied using a commercial full-field digital mammography unit. Contrast in subtracted phantom images (one mask and one post-CM) is linear as function of iodine concentration, although the sensitivity (contrast per iodine concentration) decreases beyond 8 mg/mL. This calibration seems to apply only to thin and normal thickness breasts.

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

    SciTech Connect

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

    2006-08-15

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

  11. Slow gantry rotation acquisition technique for on-board four-dimensional digital tomosynthesis

    SciTech Connect

    Maurer, Jacqueline; Pan Tinsu; Yin, Fang-Fang

    2010-02-15

    Purpose: Four-dimensional cone-beam computed tomography (4D CBCT) has been investigated for motion imaging in the radiotherapy treatment room. The drawbacks of 4D CBCT are long scan times and high imaging doses. The aims of this study were to develop and investigate a slow gantry rotation acquisition protocol for four-dimensional digital tomosynthesis (4D DTS) as a faster, lower dose alternative to 4D CBCT. Methods: This technique was implemented using an On-Board Imager kV imaging system (Varian Medical Systems, Palo Alto, CA) mounted on the gantry of a linear accelerator. The general procedure for 4D DTS imaging using slow gantry rotation acquisition consists of the following steps: (1) acquire projections over a limited gantry rotation angle in a single motion with constant frame rate and gantry rotation speed; (2) generate a respiratory signal and temporally match projection images with appropriate points from the respiratory signal; (3) use the respiratory signal to assign phases to each of the projection images; (4) sort projection images into phase bins; and (5) reconstruct phase images. Phantom studies were conducted to validate theoretically derived relationships between acquisition and respiratory parameters. Optimization of acquisition parameters was then conducted by simulating lung scans using patient data. Lung tumors with approximate volumes ranging from 0.12 to 1.53 cm{sup 3} were studied. Results: A protocol for slow gantry rotation 4D DTS was presented. Equations were derived to express relationships between acquisition parameters (frame rate, phase window, and angular intervals between projections), respiratory cycle durations, and resulting acquisition times and numbers of projections. The phantom studies validated the relationships, and the patient studies resulted in determinations of appropriate acquisition parameters. The phase window must be set according to clinical goals. For 10% phase windows, we found that appropriate frame rates

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

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

  13. Near-infrared spectral tomography integrated with digital breast tomosynthesis: Effects of tissue scattering on optical data acquisition design

    SciTech Connect

    Michaelsen, Kelly; Krishnaswamy, Venkat; Pogue, Brian W.; Poplack, Steven P.; Paulsen, Keith D.

    2012-07-15

    Purpose: Design optimization and phantom validation of an integrated digital breast tomosynthesis (DBT) and near-infrared spectral tomography (NIRST) system targeting improvement in sensitivity and specificity of breast cancer detection is presented. Factors affecting instrumentation design include minimization of cost, complexity, and examination time while maintaining high fidelity NIRST measurements with sufficient information to recover accurate optical property maps. Methods: Reconstructed DBT slices from eight patients with abnormal mammograms provided anatomical information for the NIRST simulations. A limited frequency domain (FD) and extensive continuous wave (CW) NIRST system was modeled. The FD components provided tissue scattering estimations used in the reconstruction of the CW data. Scattering estimates were perturbed to study the effects on hemoglobin recovery. Breast mimicking agar phantoms with inclusions were imaged using the combined DBT/NIRST system for comparison with simulation results. Results: Patient simulations derived from DBT images show successful reconstruction of both normal and malignant lesions in the breast. They also demonstrate the importance of accurately quantifying tissue scattering. Specifically, 20% errors in optical scattering resulted in 22.6% or 35.1% error in quantification of total hemoglobin concentrations, depending on whether scattering was over- or underestimated, respectively. Limited frequency-domain optical signal sampling provided two regions scattering estimates (for fat and fibroglandular tissues) that led to hemoglobin concentrations that reduced the error in the tumor region by 31% relative to when a single estimate of optical scattering was used throughout the breast volume of interest. Acquiring frequency-domain data with six wavelengths instead of three did not significantly improve the hemoglobin concentration estimates. Simulation results were confirmed through experiments in two-region breast mimicking

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

  16. 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.

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

    PubMed

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

    2012-08-01

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

  18. 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

  19. Assessment of mass detection performance in contrast enhanced digital mammography

    NASA Astrophysics Data System (ADS)

    Carton, Ann-Katherine; de Carvalho, Pablo M.; Li, Zhijin; Dromain, Clarisse; Muller, Serge

    2015-03-01

    We address the detectability of contrast-agent enhancing masses for contrast-agent enhanced spectral mammography (CESM), a dual-energy technique providing functional projection images of breast tissue perfusion and vascularity using simulated CESM images. First, the realism of simulated CESM images from anthropomorphic breast software phantoms generated with a software X-ray imaging platform was validated. Breast texture was characterized by power-law coefficients calculated in data sets of real clinical and simulated images. We also performed a 2-alternative forced choice (2-AFC) psychophysical experiment whereby simulated and real images were presented side-by-side to an experienced radiologist to test if real images could be distinguished from the simulated images. It was found that texture in our simulated CESM images has a fairly realistic appearance. Next, the relative performance of human readers and previously developed mathematical observers was assessed for the detection of iodine-enhancing mass lesions containing different contrast agent concentrations. A four alternative-forced-choice (4 AFC) task was designed; the task for the model and human observer was to detect which one of the four simulated DE recombined images contained an iodineenhancing mass. Our results showed that the NPW and NPWE models largely outperform human performance. After introduction of an internal noise component, both observers approached human performance. The CHO observer performs slightly worse than the average human observer. There is still work to be done in improving model observers as predictors of human-observer performance. Larger trials could also improve our test statistics. We hope that in the future, this framework of software breast phantoms, virtual image acquisition and processing, and mathematical observers can be beneficial to optimize CESM imaging techniques.

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

    NASA Astrophysics Data System (ADS)

    Baysal, Mehmet A.; Toker, Emre

    2005-09-01

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

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

    PubMed Central

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

    2014-01-01

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

  2. Beyond the mammography debate: a moderate perspective.

    PubMed

    Kaniklidis, C

    2015-06-01

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

  3. 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.

  4. 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

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

    SciTech Connect

    Saunders, Robert S. Jr; Samei, Ehsan

    2008-10-15

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

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

    NASA Astrophysics Data System (ADS)

    Marcovici, Sorin; Sukhovatkin, Vlad; Oakham, Peter

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

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

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed Central

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

    2009-01-01

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

  10. Assembly and evaluation of a training module and dataset with feedback for improved interpretation of digital breast tomosynthesis examinations

    NASA Astrophysics Data System (ADS)

    Gur, David; Zuley, Margarita L.; Sumkin, Jules H.; Hakim, Christiane M.; Chough, Denise M.; Lovy, Linda; Sobran, Cynthia; Logue, Durwin; Zheng, Bin; Klym, Amy H.

    2012-02-01

    The FDA recently approved Digital Breast Tomosynthesis (DBT) for use in screening for the early detection of breast cancer. However, MQSA qualification for interpreting DBT through training was noted as important. Performance issues related to training are largely unknown. Therefore, we assembled a unique computerized training module to assess radiologists' performances before and after using the training module. Seventy-one actual baseline mammograms (no priors) with FFDM and DBT images were assembled to be read before and after training with the developed module. Fifty examinations of FFDM and DBT images enriched with positive findings were assembled for the training module. Depicted findings were carefully reviewed, summarized, and entered into a specially designed training database where findings were identified by case number and synchronized to the display of the related FFDM plus DBT examinations on a clinical workstation. Readers reported any findings using screening BIRADS (0, 1, or 2) followed by instantaneous feedback of the verified truth. Six radiologists participated in the study and reader average sensitivity and specificity were compared before and after training. Average sensitivity improved and specificity remained relatively the same after training. Performance changes may be affected by disease prevalence in the training set.

  11. 2D and 3D registration methods for dual-energy contrast-enhanced digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Lau, Kristen C.; Roth, Susan; Maidment, Andrew D. A.

    2014-03-01

    Contrast-enhanced digital breast tomosynthesis (CE-DBT) uses an iodinated contrast agent to image the threedimensional breast vasculature. The University of Pennsylvania is conducting a CE-DBT clinical study in patients with known breast cancers. The breast is compressed continuously and imaged at four time points (1 pre-contrast; 3 postcontrast). A hybrid subtraction scheme is proposed. First, dual-energy (DE) images are obtained by a weighted logarithmic subtraction of the high-energy and low-energy image pairs. Then, post-contrast DE images are subtracted from the pre-contrast DE image. This hybrid temporal subtraction of DE images is performed to analyze iodine uptake, but suffers from motion artifacts. Employing image registration further helps to correct for motion, enhancing the evaluation of vascular kinetics. Registration using ANTS (Advanced Normalization Tools) is performed in an iterative manner. Mutual information optimization first corrects large-scale motions. Normalized cross-correlation optimization then iteratively corrects fine-scale misalignment. Two methods have been evaluated: a 2D method using a slice-by-slice approach, and a 3D method using a volumetric approach to account for out-of-plane breast motion. Our results demonstrate that iterative registration qualitatively improves with each iteration (five iterations total). Motion artifacts near the edge of the breast are corrected effectively and structures within the breast (e.g. blood vessels, surgical clip) are better visualized. Statistical and clinical evaluations of registration accuracy in the CE-DBT images are ongoing.

  12. Changes in frequency of recall recommendations of examinations depicting cancer with the availability of either priors or digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Hakim, Christiane M.; Bandos, Andriy I.; Ganott, Marie A.; Catullo, Victor J.; Chough, Denise M.; Kelly, Amy E.; Shinde, Dilip D.; Sumkin, Jules H.; Wallace, Luisa P.; Nishikawa, Robert M.; Gur, David

    2016-03-01

    Performance changes in a binary environment when using additional information is affected only when changes in recommendations are made due to the additional information in question. In a recent study, we have shown that, contrary to general expectation, introducing prior examinations improved recall rates, but not sensitivity. In this study, we assessed cancer detection differences when prior examinations and/or digital breast tomosynthesis (DBT) were made available to the radiologist. We identified a subset of 21 cancer cases with differences in the number of radiologists who recalled these cases after reviewing either a prior examination or DBT. For the cases with differences in recommendations after viewing either priors or DBT, separately, we evaluated the total number of readers that changed their recommendations, regardless of the specific radiologist in question. Confidence intervals for the number of readers and a test for the hypothesis of no difference was performed using the non-parameteric bootstrap approach addressing both case and reader-related sources of variability by resampling cases and readers. With the addition of priors, there were 14 cancer cases (out of 15) where the number of "recalling radiologists" decreased. With the addition of DBT, the number of "recalling radiologists" decreased in only five cases (out of 15) while increasing in the remaining 9 cases. Unlike most new approaches to breast imaging DBT seems to improve both recall rates and cancer detection rates. Changes in recommendations were noted by all radiologists for all cancers by type, size, and breast density.

  13. Simplified false-positive reduction in computer-aided detection scheme of clustered microcalcifications in digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Jeong, Ji-Wook; Chae, Seung-Hoon; Lee, Sooyeul; Chae, Eun Young; Kim, Hak Hee; Choi, Young-Wook

    2015-03-01

    A computer-aided detection (CADe) system for clustered microcalcifications (MCs) in reconstructed digital breast tomosynthesis (DBT) volumes was suggested. The system consisted of prescreening, MC detecting, clustering, and falsepositive reduction steps. In the prescreening stage, the MC-like objects were enhanced by a multiscale-based 3D calcification response function. A connected component segmentation method was used to detect cluster seed objects, which were considered as potential clustering centers of MCs. Starting with each cluster seed object as the initial cluster center, a cluster candidate was formed by including nearby MC candidates within a 3D neighborhood of the cluster seed object satisfying the clustering criteria during the clustering step. The size and number of the clustered MCs in a cluster seed candidate were used to reduce the number of FPs. A bounding cube for each MCC was generated for each accepted seed candidates. Then, the overlapping cubes were combined and examined according to the FP reduction criteria. After FP reduction step, we obtained the average number of FPs of 2.47 per DBT volume with sensitivity of 83.3%. Our study indicates the simplified false-positive reduction approach applied to the detection of clustered MCs in DBT is promising as an efficient CADe system.

  14. Comparing Digital Tomosynthesis to Cone-Beam CT for Position Verification in Patients Undergoing Partial Breast Irradiation

    SciTech Connect

    Zhang Junan Wu, Q. Jackie; Godfrey, Devon J.; Fatunase, Toyosi; Marks, Lawrence B.; Yin Fangfang

    2009-03-01

    Purpose: To evaluate digital tomosynthesis (DTS) technology for daily positioning of patients receiving accelerated partial breast irradiation (APBI) and to compare the positioning accuracy of DTS to three-dimensional cone-beam computed tomography (CBCT). Methods and Materials: Ten patients who underwent APBI were scanned daily with on-board CBCT. A subset of the CBCT projections was used to reconstruct a stack of DTS image slices. To optimize soft-tissue visibility, the DTS images were reconstructed in oblique directions so that the tumor bed, breast tissue, ribs, and lungs were well separated. Coronal and sagittal DTS images were also reconstructed. Translational shifts of DTS images were obtained on different days from the same patients and were compared with the translational shifts of corresponding CBCT images. Seventy-seven CBCT scans and 291 DTS scans were obtained from nine evaluable patients. Results: Tumor beds were best visible in the oblique DTS scans. One-dimensional positioning differences between DTS and CBCT images were 0.8-1.7 mm for the six patients with clips present and 1.2-2.0 mm for the three patients without clips. Because of the limited DTS scan angle, the DTS registration accuracy along the off-plane direction is lower than the accuracy along the in-plane directions. Conclusions: For patients receiving APBI, DTS localization offers comparable accuracy to CBCT localization for daily patient positioning while reducing mechanical constraints and imaging dose.

  15. Physical and psychophysical evaluation of digital systems for mammography

    NASA Astrophysics Data System (ADS)

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

    1995-04-01

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

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

    SciTech Connect

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

    2006-03-15

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

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

    SciTech Connect

    Kappadath, S. Cheenu; Shaw, Chris C.

    2005-11-15

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

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

    SciTech Connect

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

    2010-03-15

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

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

    PubMed

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

    2012-04-01

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

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

    PubMed Central

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

    2008-01-01

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

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

    PubMed Central

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

    2010-01-01

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

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

    PubMed

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

    2015-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-05-01

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

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

    PubMed

    Soliman, K; Bakkari, M

    2015-07-01

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

  5. 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

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

    PubMed Central

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Baysal, Mehmet A.; Toker, Emre

    2006-03-01

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

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  11. 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.

  12. Application of boundary detection information in breast tomosynthesis reconstruction

    SciTech Connect

    Zhang Yiheng; Chan, H.-P.; Sahiner, Berkman; Wu Yita; Zhou Chuan; Ge Jun; Wei Jun; Hadjiiski, Lubomir M.

    2007-09-15

    Digital tomosynthesis mammography (DTM) is one of the most promising techniques that can potentially improve early detection of breast cancers. DTM can provide three-dimensional (3D) structural information by reconstructing the whole imaged volume from a sequence of projection-view (PV) mammograms that are acquired at a small number of projection angles over a limited angular range. Our previous study showed that simultaneous algebraic reconstruction technique (SART) can produce satisfactory tomosynthesized image quality compared to maximum likelihood-type algorithms. To improve the efficiency of DTM reconstruction and address the problem of boundary artifacts, we have developed methods to incorporate both two-dimensional (2D) and 3D breast boundary information within the SART reconstruction algorithm in this study. A second generation GE prototype tomosynthesis mammography system with a stationary digital detector was used for PV image acquisition from 21 angles in 3 deg. increments over a {+-}30 deg. angular range. The 2D breast boundary curves on all PV images were obtained by automated segmentation and were used to restrict the SART reconstruction to be performed only within the breast volume. The computation time of SART reconstruction was reduced by 76.3% and 69.9% for cranio-caudal and mediolateral oblique views, respectively, for the chosen example. In addition, a 3D conical trimming method was developed in which the 2D breast boundary curves from all PVs were back projected to generate the 3D breast surface. This 3D surface was then used to eliminate the multiple breast shadows outside the breast volume due to reconstruction by setting these voxels to a constant background value. Our study demonstrates that, by using the 2D and 3D breast boundary information, all breast boundary and most detector boundary artifacts can be effectively removed on all tomosynthesized slices.

  13. Pursuing optimal thresholds to recommend breast biopsy by quantifying the value of tomosynthesis

    NASA Astrophysics Data System (ADS)

    Wu, Yirong; Alagoz, Oguzhan; Vanness, David J.; Trentham-Dietz, Amy; Burnside, Elizabeth S.

    2014-03-01

    A 2% threshold has been traditionally used to recommend breast biopsy in mammography. We aim to characterize how the biopsy threshold varies to achieve the maximum expected utility (MEU) of tomosynthesis for breast cancer diagnosis. A cohort of 312 patients, imaged with standard full field digital mammography (FFDM) and digital breast tomosynthesis (DBT), was selected for a reader study. Fifteen readers interpreted each patient's images and estimated the probability of malignancy using two modes: FFDM versus FFDM + DBT. We generated receiver operator characteristic (ROC) curves with the probabilities for all readers combined. We found that FFDM+DBT provided improved accuracy and MEU compared with FFDM alone. When DBT was included in the diagnosis along with FFDM, the optimal biopsy threshold increased to 2.7% as compared with the 2% threshold for FFDM alone. While understanding the optimal threshold from a decision analytic standpoint will not help physicians improve their performance without additional guidance (e.g. decision support to reinforce this threshold), the discovery of this level does demonstrate the potential clinical improvements attainable with DBT. Specifically, DBT has the potential to lead to substantial improvements in breast cancer diagnosis since it could reduce the number of patients recommended for biopsy while preserving the maximal expected utility.

  14. Evaluation of the technical performance of three different commercial digital breast tomosynthesis systems in the clinical environment.

    PubMed

    Rodríguez-Ruiz, A; Castillo, M; Garayoa, J; Chevalier, M

    2016-06-01

    The aim of this work was to research and evaluate the performance of three different digital breast tomosynthesis (DBT) systems in the clinical environment (Siemens Mammomat Inspiration, Hologic Selenia Dimensions, and Fujifilm Amulet Innovality). The characterization included the study of the detector, the automatic exposure control, and the resolution of DBT projections and reconstructed planes. The modulation transfer function (MTF) of the DBT projections was measured with a 1mm thick steel edge, showing a strong anisotropy (30-40% lower MTF0.5 frequencies in the tube travel direction). The in-plane MTF0.5, measured with a 25μm tungsten wire, ranges from 1.3 to 1.8lp/mm in the tube-travel direction and between 2.4 and 3.7lp/mm in the chest wall-nipple. In the latter direction, the MTF peak shift is more emphasized for large angular range systems (2.0 versus 1.0lp/mm). In-depth resolution of the planes, via the full width at half maximum (FWHM) from the point spread function of a 25μm tungsten wire, is not only influenced by angular range and yields 1.3-4.6mm among systems. The artifact spread function from 1mm diameter tungsten beads depends mainly on angular range, yielding two tendencies whether large (FWHM is 4.5mm) or small (FWHM is 10mm) angular range is used. DBT delivers per scan a mean glandular dose between 1.4 and 2.7mGy for a 45mm thick polymethyl methacrylate (PMMA) block. In conclusion, we have identified and analysed specific metrics that can be used for quality assurance of DBT systems. PMID:27180118

  15. Optimization of continuous tube motion and step-and-shoot motion in digital breast tomosynthesis systems with patient motion

    NASA Astrophysics Data System (ADS)

    Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2012-03-01

    In digital breast tomosynthesis (DBT), a reconstruction of the breast is generated from projections acquired over a limited range of x-ray tube angles. There are two principal schemes for acquiring projections, continuous tube motion and step-and-shoot motion. Although continuous tube motion has the benefit of reducing patient motion by lowering scan time, it has the drawback of introducing blurring artifacts due to focal spot motion. The purpose of this work is to determine the optimal scan time which minimizes this trade-off. To this end, the filtered backprojection reconstruction of a sinusoidal input is calculated. At various frequencies, the optimal scan time is determined by the value which maximizes the modulation of the reconstruction. Although prior authors have studied the dependency of the modulation on focal spot motion, this work is unique in also modeling patient motion. It is shown that because continuous tube motion and patient motion have competing influences on whether scan time should be long or short, the modulation is maximized by an intermediate scan time. This optimal scan time decreases with object velocity and increases with exposure time. To optimize step-and-shoot motion, we calculate the scan time for which the modulation attains the maximum value achievable in a comparable system with continuous tube motion. This scan time provides a threshold below which the benefits of step-and-shoot motion are justified. In conclusion, this work optimizes scan time in DBT systems with patient motion and either continuous tube motion or step-and-shoot motion by maximizing the modulation of the reconstruction.

  16. Detection of calcification clusters in digital breast tomosynthesis slices at different dose levels utilizing a SRSAR reconstruction and JAFROC

    NASA Astrophysics Data System (ADS)

    Timberg, P.; Dustler, M.; Petersson, H.; Tingberg, A.; Zackrisson, S.

    2015-03-01

    Purpose: To investigate detection performance for calcification clusters in reconstructed digital breast tomosynthesis (DBT) slices at different dose levels using a Super Resolution and Statistical Artifact Reduction (SRSAR) reconstruction method. Method: Simulated calcifications with irregular profile (0.2 mm diameter) where combined to form clusters that were added to projection images (1-3 per abnormal image) acquired on a DBT system (Mammomat Inspiration, Siemens). The projection images were dose reduced by software to form 35 abnormal cases and 25 normal cases as if acquired at 100%, 75% and 50% dose level (AGD of approximately 1.6 mGy for a 53 mm standard breast, measured according to EUREF v0.15). A standard FBP and a SRSAR reconstruction method (utilizing IRIS (iterative reconstruction filters), and outlier detection using Maximum-Intensity Projections and Average-Intensity Projections) were used to reconstruct single central slices to be used in a Free-response task (60 images per observer and dose level). Six observers participated and their task was to detect the clusters and assign confidence rating in randomly presented images from the whole image set (balanced by dose level). Each trial was separated by one weeks to reduce possible memory bias. The outcome was analyzed for statistical differences using Jackknifed Alternative Free-response Receiver Operating Characteristics. Results: The results indicate that it is possible reduce the dose by 50% with SRSAR without jeopardizing cluster detection. Conclusions: The detection performance for clusters can be maintained at a lower dose level by using SRSAR reconstruction.

  17. Evaluation of three types of reference image data for external beam radiotherapy target localization using digital tomosynthesis (DTS)

    SciTech Connect

    Godfrey, Devon J.; Ren Lei; Yan Hui; Wu, Q.; Yoo Sua; Oldham, M.; Yin Fangfang

    2007-08-15

    Digital tomosynthesis (DTS) is a fast, low-dose three-dimensional (3D) imaging approach which yields slice images with excellent in-plane resolution, though low plane-to-plane resolution. A stack of DTS slices can be reconstructed from a single limited-angle scan, with typical scan angles ranging from 10 deg. to 40 deg. and acquisition times of less than 10 s. The resulting DTS slices show soft tissue contrast approaching that of full cone-beam CT. External beam radiotherapy target localization using DTS requires the registration of on-board DTS images with corresponding reference image data. This study evaluates three types of reference volume: original reference CT, exact reference DTS (RDTS), and a more computationally efficient approximate reference DTS (RDTS{sub approx}), as well as three different DTS scan angles (22 deg., 44 deg., and 65 deg.) for the DTS target localization task. Three-dimensional mutual information (MI) shared between reference and on-board DTS volumes was computed in a region surrounding the spine of a chest phantom, as translations spanning {+-}5 mm and rotations spanning {+-}5 deg. were simulated along each dimension in the reference volumes. The locations of the MI maxima were used as surrogates for registration accuracy, and the width of the MI peaks were used to characterize the registration robustness. The results show that conventional treatment planning CT volumes are inadequate reference volumes for direct registration with on-board DTS data. The efficient RDTS{sub approx} method also appears insufficient for MI-based registration without further refinement of the technique, though it may be suitable for manual registration performed by a human observer. The exact RDTS volumes, on the other hand, delivered a 3D DTS localization accuracy of 0.5 mm and 0.5 deg. along each axis, using only a single 44 deg. coronal on-board DTS scan of the chest phantom.

  18. Digital breast tomosynthesis: effects of projection-view distribution on computer-aided detection of microcalcification clusters

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    We investigated the effect of projection view (PV) distribution on detectability of microcalcification clusters (MC) in digital breast tomosynthesis (DBT) by a computer-aided detection (CAD) system. With IRB approval, DBT of breasts with biopsy-proven MCs were acquired with 60° tomographic angle, 21 PVs, and 3° increment (full set). The DBT volume was reconstructed using simultaneous algebraic reconstruction technique (SART) with multiscale bilateral filtering (MSBF) regularization. Three subsets simulating acquisition with 11, 9 and 11 PVs at tomographic angle and angular increment of (30°, 3°), (24°, 3°) and (60°, 6°), respectively, were also reconstructed with MSBF-regularized SART at several iterations. The subsets therefore had about half the dose of the full set. An enhancement-modulated multiscale calcification response volume was derived, and prescreening of the individual microcalcification candidates was performed in this volume. Iterative thresholding in combination with region growing identified the potential microcalcification candidates. The prescreening sensitivity was analyzed using the mean and standard deviation of the signal-to-noise ratio (SNR) of the microcalcification candidates and rank-sensitivity plot. The candidates of MCs were detected by dynamic clustering using SNR and distance criteria. No additional FP reduction steps were performed to avoid the variability due to parameter tuning for a small data set. The performance of MC detection was compared at this stage. For the three subsets, view-based FROC analysis showed that the lowest FP rates at 90% sensitivity was achieved at 6.2, 11.8 and 9.0 per volume, respectively, compared to that of the full set at 3.9. The (30°, 3°) set performed better than the other two subsets.

  19. A digital x-ray tomosynthesis coupled near infrared spectral tomography system for dual-modality breast imaging.

    PubMed

    Krishnaswamy, Venkataramanan; Michaelsen, Kelly E; Pogue, Brian W; Poplack, Steven P; Shaw, Ian; Defrietas, Ken; Brooks, Ken; Paulsen, Keith D

    2012-08-13

    A Near Infrared Spectral Tomography (NIRST) system has been developed and integrated into a commercial Digital Breast Tomosynthesis (DBT) scanner to allow structural and functional imaging of breast in vivo. The NIRST instrument uses an 8-wavelength continuous wave (CW) laser-based scanning source assembly and a 75-element silicon photodiode solid-state detector panel to produce dense spectral and spatial projection data from which spectrally constrained 3D tomographic images of tissue chromophores are produced. Integration of the optical imaging system into the DBT scanner allows direct co-registration of the optical and DBT images, while also facilitating the synergistic use of x-ray contrast as anatomical priors in optical image reconstruction. Currently, the total scan time for a combined NIRST-DBT exam is ~50s with data collection from 8 wavelengths in the optical scan requiring ~42s to complete. The system was tested in breast simulating phantoms constructed using intralipid and blood in an agarose matrix with a 3 cm x 2 cm cylindrical inclusion at 1 cm depth from the surface. Diffuse image reconstruction of total hemoglobin (HbT) concentration resulted in accurate recovery of the lateral size and position of the inclusion to within 6% and 8%, respectively. Use of DBT structural priors in the NIRST reconstruction process improved the quantitative accuracy of the HbT recovery, and led to linear changes in imaged versus actual contrast, underscoring the advantages of dual-modality optical imaging approaches. The quantitative accuracy of the system can be further improved with independent measurements of scattering properties through integration of frequency or time domain data. PMID:23038553

  20. 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.

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

    PubMed Central

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

    2015-01-01

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

  2. 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.

  3. 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

  4. 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.

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

    PubMed

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

    2011-09-01

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

  6. 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.

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

    PubMed

    Bernhardt, Philipp; Mertelmeier, Thomas; Hoheisel, Martin

    2006-11-01

    In contrast to conventional analog screen-film mammography new flat detectors have a high dynamic range and a linear characteristic curve. Hence, the radiographic technique can be optimized independently of the receptor exposure. It can be exclusively focused on the improvement of the image quality and the reduction of the patient dose. In this paper we measure the image quality by a physical quantity, the signal difference-to-noise ratio (SDNR), and the patient risk by the average glandular dose (AGD). Using these quantities, we compare the following different setups through simulations and phantom studies regarding the detection of microcalcifications and tumors for different breast thicknesses and breast compositions: Monochromatic radiation, three different anode/filter combinations: Molybdenum/molybdenum (Mo/Mo), molybdenum/rhodium (Mo/Rh), and tungsten/rhodium (W/Rh), different filter thicknesses, use of anti-scatter grids, and different tube voltages. For a digital mammography system based on an amorphous selenium detector it turned out that, first, the W/Rh combination is the best choice for all detection tasks studied. Second, monochromatic radiation can further reduce the AGD by a factor of up to 2.3, maintaining the image quality in comparison with a real polychromatic spectrum of an x-ray tube. And, third, the use of an anti-scatter grid is only advantageous for breast thicknesses larger than approximately 5 cm. PMID:17153413

  8. Self-masking subtraction tomosynthesis

    SciTech Connect

    Chakraborty, D.P.; Yester, M.V.; Barnes, G.T.; Lakshminarayanan, A.V.

    1984-01-01

    The authors tested the image quality and dose savings of self-masking subtraction tomosynthesis (SST), which combines digital tomosynthesis with subtraction of a blurred self-mask. High-quality images of the inner ear of a head phantom were obtained at moderate dose savings. Although they were taken with linear motion, they did not exhibit the streaking due to off-fulcrum objects that is characteristic of conventional linear tomography. SST could reduce patient dose by a factor of at least 12 in examinations of the inner ear, and the mechanical aspects can be implemented with moderate modifications of existing instrumentation.

  9. Feasibility study for image reconstruction in circular digital tomosynthesis (CDTS) from limited-scan angle data based on compressed-sensing theory

    NASA Astrophysics Data System (ADS)

    Park, Yeonok; Je, Uikyu; Cho, Hyosung; Hong, Daeki; Park, Chulkyu; Cho, Heemoon; Choi, Sungil; Woo, Taeho

    2015-03-01

    In this work, we performed a feasibility study for image reconstruction in a circular digital tomosynthesis (CDTS) from limited-scan angle data based on compressed-sensing (CS) theory. Here, the X-ray source moves along an arc within a limited-scan angle (≤ 180°) on a circular path set perpendicularly to the axial direction during the image acquisition. This geometry, compared to full-angle (360°) scan geometry, allows imaging system to be designed more compactly and gives better tomographic quality than conventional linear digital tomosynthesis (DTS). We implemented an efficient CS-based reconstruction algorithm for the proposed geometry and performed systematic simulations to investigate the image characteristics. We successfully reconstructed CDTS images with incomplete projections acquired at several selected limited-scan angles of 45°, 90°, 135°, and 180° for a given tomographic angle of 80° and evaluated the reconstruction quality. Our simulation results indicate that the proposed method can provide superior tomographic quality for axial view and even for the other views (i.e., sagittal and coronal), as in computed tomography, to conventional DTS.

  10. Importance of point-by-point back projection correction for isocentric motion in digital breast tomosynthesis: Relevance to morphology of structures such as microcalcifications

    SciTech Connect

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

    2007-10-15

    Digital breast tomosynthesis is a three-dimensional imaging technique that provides an arbitrary set of reconstruction planes in the breast from a limited-angle series of projection images acquired while the x-ray tube moves. Traditional shift-and-add (SAA) tomosynthesis reconstruction is a common mathematical method to line up each projection image based on its shifting amount to generate reconstruction slices. With parallel-path geometry of tube motion, the path of the tube lies in a plane parallel to the plane of the detector. The traditional SAA algorithm gives shift amounts for each projection image calculated only along the direction of x-ray tube movement. However, with the partial isocentric motion of the x-ray tube in breast tomosynthesis, small objects such as microcalcifications appear blurred (for instance, about 1-4 pixels in blur for a microcalcification in a human breast) in traditional SAA images in the direction perpendicular to the direction of tube motion. Some digital breast tomosynthesis algorithms reported in the literature utilize a traditional one-dimensional SAA method that is not wholly suitable for isocentric motion. In this paper, a point-by-point back projection (BP) method is described and compared with traditional SAA for the important clinical task of evaluating morphology of small objects such as microcalcifications. Impulse responses at different three-dimensional locations with five different combinations of imaging acquisition parameters were investigated. Reconstruction images of microcalcifications in a human subject were also evaluated. Results showed that with traditional SAA and 45 deg. view angle of tube movement with respect to the detector, at the same height above the detector, the in-plane blur artifacts were obvious for objects farther away from x-ray source. In a human subject, the appearance of calcifications was blurred in the direction orthogonal to the tube motion with traditional SAA. With point-by-point BP, the

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

    PubMed

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

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    PubMed Central

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

    2008-01-01

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

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

    PubMed

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

    2007-09-01

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

  15. Clinical Evaluation of Positioning Verification Using Digital Tomosynthesis and Bony Anatomy and Soft Tissues for Prostate Image-Guided Radiotherapy

    SciTech Connect

    Yoo, Sua Wu, Q. Jackie; Godfrey, Devon; Yan Hui; Ren Lei; Das, Shiva; Lee, William R.; Yin Fangfang

    2009-01-01

    Purpose: To evaluate on-board digital tomosynthesis (DTS) for patient positioning vs. two-dimensional (2D) radiography and three-dimensional cone beam (CBCT). Methods and Materials: A total of 92 image sessions from 9 prostate cancer patients were analyzed. An on-board image set was registered to a corresponding reference image set. Four pairs of image sets were used: digitally reconstructed radiographs vs. on-board orthogonal paired radiographs for the 2D method, coronal-reference DTS vs. on-board coronal DTS for the coronal-DTS method, sagittal-reference DTS vs. on-board sagittal DTS for the sagittal-DTS method, and planning CT vs. CBCT for the CBCT method. The registration results were compared. Results: The systematic errors in all methods were <1 mm/1{sup o}. When registering the bony anatomy, the mean vector difference was 0.21 {+-} 0.11 cm between 2D and CBCT, 0.11 {+-} 0.08 cm between CBCT and coronal DTS, and 0.14 {+-} 0.07 cm between CBCT and sagittal DTS. The correlation between CBCT to DTS was stronger (coefficient = 0.92-0.95) than the correlation between 2D and CBCT or DTS (coefficient = 0.81-0.83). When registering the soft tissue, the mean vector difference was 0.18 {+-} 0.11 cm between CBCT and coronal DTS and 0.29 {+-} 0.17 cm between CBCT and sagittal DTS. The correlation coefficient of CBCT to sagittal DTS and to coronal DTS was 0.84 and 0.92, respectively. Conclusion: DTS could provide equivalent results to CBCT when the bony anatomy is used as landmarks for prostate image-guided radiotherapy. For soft tissue-based positioning verification, coronal DTS produced equivalent results to CBCT, but sagittal DTS alone was insufficient. DTS could allow for comparable soft tissue-based target localization with faster scanning time and a lower imaging dose compared with CBCT.

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

    PubMed

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

    2010-01-01

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

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

    PubMed Central

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

    2014-01-01

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

  18. Multichannel response analysis on 2D projection views for detection of clustered microcalcifications in digital breast tomosynthesis

    SciTech Connect

    Wei, Jun Chan, Heang-Ping; Hadjiiski, Lubomir M.; Helvie, Mark A.; Lu, Yao; Zhou, Chuan; Samala, Ravi

    2014-04-15

    Purpose: To investigate the feasibility of a new two-dimensional (2D) multichannel response (MCR) analysis approach for the detection of clustered microcalcifications (MCs) in digital breast tomosynthesis (DBT). Methods: With IRB approval and informed consent, a data set of two-view DBTs from 42 breasts containing biopsy-proven MC clusters was collected in this study. The authors developed a 2D approach for MC detection using projection view (PV) images rather than the reconstructed three-dimensional (3D) DBT volume. Signal-to-noise ratio (SNR) enhancement processing was first applied to each PV to enhance the potential MCs. The locations of MC candidates were then identified with iterative thresholding. The individual MCs were decomposed with Hermite–Gaussian (HG) and Laguerre–Gaussian (LG) basis functions and the channelized Hotelling model was trained to produce the MCRs for each MC on the 2D images. The MCRs from the PVs were fused in 3D by a coincidence counting method that backprojects the MC candidates on the PVs and traces the coincidence of their ray paths in 3D. The 3D MCR was used to differentiate the true MCs from false positives (FPs). Finally a dynamic clustering method was used to identify the potential MC clusters in the DBT volume based on the fact that true MCs of clinical significance appear in clusters. Using two-fold cross validation, the performance of the 3D MCR for classification of true and false MCs was estimated by the area under the receiver operating characteristic (ROC) curve and the overall performance of the MCR approach for detection of clustered MCs was assessed by free response receiver operating characteristic (FROC) analysis. Results: When the HG basis function was used for MCR analysis, the detection of MC cluster achieved case-based test sensitivities of 80% and 90% at the average FP rates of 0.65 and 1.55 FPs per DBT volume, respectively. With LG basis function, the average FP rates were 0.62 and 1.57 per DBT volume at

  19. Computer-aided detection of clustered microcalcifications in multiscale bilateral filtering regularized reconstructed digital breast tomosynthesis volume

    SciTech Connect

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

    2014-02-15

    Purpose: Develop a computer-aided detection (CADe) system for clustered microcalcifications in digital breast tomosynthesis (DBT) volume enhanced with multiscale bilateral filtering (MSBF) regularization. Methods: With Institutional Review Board approval and written informed consent, two-view DBT of 154 breasts, of which 116 had biopsy-proven microcalcification (MC) clusters and 38 were free of MCs, was imaged with a General Electric GEN2 prototype DBT system. The DBT volumes were reconstructed with MSBF-regularized simultaneous algebraic reconstruction technique (SART) that was designed to enhance MCs and reduce background noise while preserving the quality of other tissue structures. The contrast-to-noise ratio (CNR) of MCs was further improved with enhancement-modulated calcification response (EMCR) preprocessing, which combined multiscale Hessian response to enhance MCs by shape and bandpass filtering to remove the low-frequency structured background. MC candidates were then located in the EMCR volume using iterative thresholding and segmented by adaptive region growing. Two sets of potential MC objects, cluster centroid objects and MC seed objects, were generated and the CNR of each object was calculated. The number of candidates in each set was controlled based on the breast volume. Dynamic clustering around the centroid objects grouped the MC candidates to form clusters. Adaptive criteria were designed to reduce false positive (FP) clusters based on the size, CNR values and the number of MCs in the cluster, cluster shape, and cluster based maximum intensity projection. Free-response receiver operating characteristic (FROC) and jackknife alternative FROC (JAFROC) analyses were used to assess the performance and compare with that of a previous study. Results: Unpaired two-tailedt-test showed a significant increase (p < 0.0001) in the ratio of CNRs for MCs with and without MSBF regularization compared to similar ratios for FPs. For view-based detection, a

  20. Digital breast tomosynthesis: studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images.

    PubMed

    Goodsitt, Mitchell M; Chan, Heang-Ping; Schmitz, Andrea; Zelakiewicz, Scott; Telang, Santosh; Hadjiiski, Lubomir; Watcharotone, Kuanwong; Helvie, Mark A; Paramagul, Chintana; Neal, Colleen; Christodoulou, Emmanuel; Larson, Sandra C; Carson, Paul L

    2014-10-01

    The effect of acquisition geometry in digital breast tomosynthesis was evaluated with studies of contrast-to-noise ratios (CNRs) and observer preference. Contrast-detail (CD) test objects in 5 cm thick phantoms with breast-like backgrounds were imaged. Twelve different angular acquisitions (average glandular dose for each ~1.1 mGy) were performed ranging from narrow angle 16° with 17 projection views (16d17p) to wide angle 64d17p. Focal slices of SART-reconstructed images of the CD arrays were selected for CNR computations and the reader preference study. For the latter, pairs of images obtained with different acquisition geometries were randomized and scored by 7 trained readers. The total scores for all images and readings for each acquisition geometry were compared as were the CNRs. In general, readers preferred images acquired with wide angle as opposed to narrow angle geometries. The mean percent preferred was highly correlated with tomosynthesis angle (R = 0.91). The highest scoring geometries were 60d21p (95%), 64d17p (80%), and 48d17p (72%); the lowest scoring were 16d17p (4%), 24d9p (17%) and 24d13p (33%). The measured CNRs for the various acquisitions showed much overlap but were overall highest for wide-angle acquisitions. Finally, the mean reader scores were well correlated with the mean CNRs (R = 0.83). PMID:25211509

  1. Clinical implementation of a digital tomosynthesis-based seed reconstruction algorithm for intraoperative postimplant dose evaluation in low dose rate prostate brachytherapy

    SciTech Connect

    Brunet-Benkhoucha, Malik; Verhaegen, Frank; Lassalle, Stephanie; Beliveau-Nadeau, Dominic; Reniers, Brigitte; Donath, David; Taussky, Daniel; Carrier, Jean-Francois

    2009-11-15

    Purpose: The low dose rate brachytherapy procedure would benefit from an intraoperative postimplant dosimetry verification technique to identify possible suboptimal dose coverage and suggest a potential reimplantation. The main objective of this project is to develop an efficient, operator-free, intraoperative seed detection technique using the imaging modalities available in a low dose rate brachytherapy treatment room. Methods: This intraoperative detection allows a complete dosimetry calculation that can be performed right after an I-125 prostate seed implantation, while the patient is still under anesthesia. To accomplish this, a digital tomosynthesis-based algorithm was developed. This automatic filtered reconstruction of the 3D volume requires seven projections acquired over a total angle of 60 deg. with an isocentric imaging system. Results: A phantom study was performed to validate the technique that was used in a retrospective clinical study involving 23 patients. In the patient study, the automatic tomosynthesis-based reconstruction yielded seed detection rates of 96.7% and 2.6% false positives. The seed localization error obtained with a phantom study is 0.4{+-}0.4 mm. The average time needed for reconstruction is below 1 min. The reconstruction algorithm also provides the seed orientation with an uncertainty of 10 deg. {+-}8 deg. The seed detection algorithm presented here is reliable and was efficiently used in the clinic. Conclusions: When combined with an appropriate coregistration technique to identify the organs in the seed coordinate system, this algorithm will offer new possibilities for a next generation of clinical brachytherapy systems.

  2. Digital breast tomosynthesis: studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images

    NASA Astrophysics Data System (ADS)

    Goodsitt, Mitchell M.; Chan, Heang-Ping; Schmitz, Andrea; Zelakiewicz, Scott; Telang, Santosh; Hadjiiski, Lubomir; Watcharotone, Kuanwong; Helvie, Mark A.; Paramagul, Chintana; Neal, Colleen; Christodoulou, Emmanuel; Larson, Sandra C.; Carson, Paul L.

    2014-10-01

    The effect of acquisition geometry in digital breast tomosynthesis was evaluated with studies of contrast-to-noise ratios (CNRs) and observer preference. Contrast-detail (CD) test objects in 5 cm thick phantoms with breast-like backgrounds were imaged. Twelve different angular acquisitions (average glandular dose for each ~1.1 mGy) were performed ranging from narrow angle 16° with 17 projection views (16d17p) to wide angle 64d17p. Focal slices of SART-reconstructed images of the CD arrays were selected for CNR computations and the reader preference study. For the latter, pairs of images obtained with different acquisition geometries were randomized and scored by 7 trained readers. The total scores for all images and readings for each acquisition geometry were compared as were the CNRs. In general, readers preferred images acquired with wide angle as opposed to narrow angle geometries. The mean percent preferred was highly correlated with tomosynthesis angle (R = 0.91). The highest scoring geometries were 60d21p (95%), 64d17p (80%), and 48d17p (72%); the lowest scoring were 16d17p (4%), 24d9p (17%) and 24d13p (33%). The measured CNRs for the various acquisitions showed much overlap but were overall highest for wide-angle acquisitions. Finally, the mean reader scores were well correlated with the mean CNRs (R = 0.83).

  3. Pre-computed backprojection based penalized-likelihood (PPL) reconstruction with an edge-preserved regularizer for stationary Digital Breast Tomosynthesis

    NASA Astrophysics Data System (ADS)

    Xu, Shiyu; Inscoe, Christy R.; Lu, Jianping; Zhou, Otto; Chen, Ying

    2014-03-01

    Stationary Digital Breast Tomosynthesis (sDBT) is a carbon nanotube based breast imaging device with fast data acquisition and decent projection resolution to provide three dimensional (3-D) volume information. To- mosynthesis 3-D image reconstruction is faced with the challenges of the cone beam geometry and the incomplete and nonsymmetric sampling due to the sparse views and limited view angle. Among all available reconstruction methods, statistical iterative method exhibits particular promising since it relies on an accurate physical and statistical model with prior knowledge. In this paper, we present the application of an edge-preserved regularizer to our previously proposed precomputed backprojection based penalized-likelihood (PPL) reconstruction. By using the edge-preserved regularizer, our experiments show that through tuning several parameters, resolution can be retained while noise is reduced significantly. Compared to other conventional noise reduction techniques in image reconstruction, less resolution is lost in order to gain certain noise reduction, which may benefit the research of low dose tomosynthesis.

  4. Digital breast tomosynthesis: Studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images

    PubMed Central

    Goodsitt, Mitchell M.; Chan, Heang-Ping; Schmitz, Andrea; Zelakiewicz, Scott; Telang, Santosh; Hadjiiski, Lubomir; Watcharotone, Kuanwong; Helvie, Mark A.; Paramagul, Chintana; Neal, Colleen; Christodoulou, Emmanuel; Larson, Sandra C.; Carson, Paul L.

    2014-01-01

    The effect of acquisition geometry in digital breast tomosynthesis (DBT) was evaluated with studies of contrast-to-noise ratios (CNRs) and observer preference. Contrast-detail (CD) test objects in 5 cm thick phantoms with breast-like backgrounds were imaged. Twelve different angular acquisitions (average glandular dose for each ~1.1 mGy) were performed ranging from narrow angle 16° with 17 projection views (16d17p) to wide angle 64d17p. Focal slices of SART-reconstructed images of the CD arrays were selected for CNR computations and the reader preference study. For the latter, pairs of images obtained with different acquisition geometries were randomized and scored by 7 trained readers. The total scores for all images and readings for each acquisition geometry were compared as were the CNRs. In general, readers preferred images acquired with wide angle as opposed to narrow angle geometries. The mean percent preferred was highly correlated with tomosynthesis angle (R=0.91). The highest scoring geometries were 60d21p (95%), 64d17p (80%), and 48d17p (72%); the lowest scoring were 16d17p (4%), 24d9p (17%) and 24d13p (33%). The measured CNRs for the various acquisitions showed much overlap but were overall highest for wide-angle acquisitions. Finally, the mean reader scores were well correlated with the mean CNRs (R=0.83). PMID:25211509

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

    NASA Astrophysics Data System (ADS)

    Kasch, Kay-Uwe; Moftah, Belal A.

    2008-01-01

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

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

    SciTech Connect

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

    2007-02-15

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

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

    PubMed

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

    2009-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  10. 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

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

    SciTech Connect

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

    2009-11-15

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

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

    SciTech Connect

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

    2015-11-15

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

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

    PubMed Central

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

    2016-01-01

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

  14. Correlating locations in ipsilateral breast tomosynthesis views using an analytical hemispherical compression model

    NASA Astrophysics Data System (ADS)

    van Schie, Guido; Tanner, Christine; Snoeren, Peter; Samulski, Maurice; Leifland, Karin; Wallis, Matthew G.; Karssemeijer, Nico

    2011-08-01

    To improve cancer detection in mammography, breast examinations usually consist of two views per breast. In order to combine information from both views, corresponding regions in the views need to be matched. In 3D digital breast tomosynthesis (DBT), this may be a difficult and time-consuming task for radiologists, because many slices have to be inspected individually. For multiview computer-aided detection (CAD) systems, matching corresponding regions is an essential step that needs to be automated. In this study, we developed an automatic method to quickly estimate corresponding locations in ipsilateral tomosynthesis views by applying a spatial transformation. First we match a model of a compressed breast to the tomosynthesis view containing a point of interest. Then we estimate the location of the corresponding point in the ipsilateral view by assuming that this model was decompressed, rotated and compressed again. In this study, we use a relatively simple, elastically deformable sphere model to obtain an analytical solution for the transformation in a given DBT case. We investigate three different methods to match the compression model to the data by using automatic segmentation of the pectoral muscle, breast tissue and nipple. For validation, we annotated 208 landmarks in both views of a total of 146 imaged breasts of 109 different patients and applied our method to each location. The best results are obtained by using the centre of gravity of the breast to define the central axis of the model, around which the breast is assumed to rotate between views. Results show a median 3D distance between the actual location and the estimated location of 14.6 mm, a good starting point for a registration method or a feature-based local search method to link suspicious regions in a multiview CAD system. Approximately half of the estimated locations are at most one slice away from the actual location, which makes the method useful as a mammographic workstation tool for

  15. Patient dose simulations for scanning-beam digital x-ray tomosynthesis of the lungs

    PubMed Central

    Nelson, Geoff; Yoon, Sungwon; Krishna, Ganesh; Wilfley, Brian; Fahrig, Rebecca

    2013-01-01

    Purpose: An improved method of image guidance for lung tumor biopsies could help reduce the high rate of false negatives. The aim of this work is to optimize the geometry of the scanning-beam digital tomography system (SBDX) for providing real-time 3D tomographic reconstructions for target verification. The unique geometry of the system requires trade-offs between patient dose, imaging field of view (FOV), and tomographic angle. Methods: Tomosynthetic angle as a function of tumor-to-detector distance was calculated. Monte Carlo Software (PCXMC) was used to calculate organ doses and effective dose for source-to-detector distances (SDDs) from 90 to 150 cm, patient locations with the tumor at 20 cm from the source to 20 cm from the detector, and FOVs centered on left lung and right lung as well as medial and distal peripheries of the lungs. These calculations were done for two systems, a SBDX system and a GE OEC-9800 C-arm fluoroscopic unit. To evaluate the dose effect of the system geometry, results from PCXMC were calculated using a scan of 300 mAs for both SBDX and fluoroscopy. The Rose Criterion was used to find the fluence required for a tumor SNR of 5, factoring in scatter, air-gap, system geometry, and patient position for all models generated with PCXMC. Using the calculated fluence for constant tumor SNR, the results from PCXMC were used to compare the patient dose for a given SNR between SBDX and fluoroscopy. Results: Tomographic angle changes with SDD only in the region near the detector. Due to their geometry, the source array and detector have a peak tomographic angle for any given SDD at a source to tumor distance that is 69.7% of the SDD assuming constant source and detector size. Changing the patient location in order to increase tomographic angle has a significant effect on organ dose distribution due to geometrical considerations. With SBDX and fluoroscopy geometries, the dose to organs typically changes in an opposing manner with changing patient

  16. Patient dose simulations for scanning-beam digital x-ray tomosynthesis of the lungs

    SciTech Connect

    Nelson, Geoff; Fahrig, Rebecca; Yoon, Sungwon; Krishna, Ganesh; Wilfley, Brian

    2013-11-15

    Purpose: An improved method of image guidance for lung tumor biopsies could help reduce the high rate of false negatives. The aim of this work is to optimize the geometry of the scanning-beam digital tomography system (SBDX) for providing real-time 3D tomographic reconstructions for target verification. The unique geometry of the system requires trade-offs between patient dose, imaging field of view (FOV), and tomographic angle.Methods: Tomosynthetic angle as a function of tumor-to-detector distance was calculated. Monte Carlo Software (PCXMC) was used to calculate organ doses and effective dose for source-to-detector distances (SDDs) from 90 to 150 cm, patient locations with the tumor at 20 cm from the source to 20 cm from the detector, and FOVs centered on left lung and right lung as well as medial and distal peripheries of the lungs. These calculations were done for two systems, a SBDX system and a GE OEC-9800 C-arm fluoroscopic unit. To evaluate the dose effect of the system geometry, results from PCXMC were calculated using a scan of 300 mAs for both SBDX and fluoroscopy. The Rose Criterion was used to find the fluence required for a tumor SNR of 5, factoring in scatter, air-gap, system geometry, and patient position for all models generated with PCXMC. Using the calculated fluence for constant tumor SNR, the results from PCXMC were used to compare the patient dose for a given SNR between SBDX and fluoroscopy.Results: Tomographic angle changes with SDD only in the region near the detector. Due to their geometry, the source array and detector have a peak tomographic angle for any given SDD at a source to tumor distance that is 69.7% of the SDD assuming constant source and detector size. Changing the patient location in order to increase tomographic angle has a significant effect on organ dose distribution due to geometrical considerations. With SBDX and fluoroscopy geometries, the dose to organs typically changes in an opposing manner with changing patient

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

    PubMed

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  19. 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.

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

    SciTech Connect

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

    2007-06-15

    The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge-on geometry connected to photon counting electronics. The pixel size is 50 {mu}m and the field of view 24x26 cm{sup 2}. The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the 7.6-206 {mu}Gy range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a 28 kV W-0.5 mm Al anode-filter combination with an added 2 mm Al filtration.

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

    PubMed

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

    2007-06-01

    The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge-on geometry connected to photon counting electronics. The pixel size is 50 microm and the field of view 24 x 26 cm2. The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the 7.6-206 microGy range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a 28 kV W-0.5 mm Al anode-filter combination with an added 2 mm Al filtration. PMID:17654894

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

    PubMed

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

    2002-02-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    SciTech Connect

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

    2006-04-15

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

  5. Optimization of phosphor-based detector design for oblique x-ray incidence in digital breast tomosynthesis

    SciTech Connect

    Acciavatti, Raymond J.; Maidment, Andrew D. A.

    2011-11-15

    Purpose: In digital breast tomosynthesis (DBT), a volumetric reconstruction of the breast is generated from a limited range of x-ray projections. One trade-off of DBT is resolution loss in the projections due to non-normal (i.e., oblique) x-ray incidence. Although degradation in image quality due to oblique incidence has been studied using empirical data and Monte Carlo simulations, a theoretical treatment has been lacking. The purpose of this work is to extend Swank's calculations of the transfer functions of turbid granular phosphors to oblique incidence. The model is ultimately used as a tool for optimizing the design of DBT detectors. Methods: A quantum-limited system and 20 keV x-rays are considered. Under these assumptions, the modulation transfer function (MTF) and noise power spectra (NPS) are derived using the diffusion approximation to the Boltzmann equation to model optical scatter within the phosphor. This approach is applicable to a nonstructured scintillator such as gadolinium oxysulfide doped with terbium (Gd{sub 2}O{sub 2}S:Tb), which is commonly used in breast imaging and which can reasonably approximate other detector materials. The detective quantum efficiency (DQE) is then determined from the Nishikawa formulation, where it is written as the product of the x-ray quantum detection efficiency, the Swank factor, and the Lubberts fraction. Transfer functions are calculated for both front- and back-screen configurations, which differ by positioning the photocathode at the exit or entrance point of the x-ray beam, respectively. Results: In the front-screen configuration, MTF and DQE are found to have considerable angular dependence, while NPS is shown to vary minimally with projection angle. As expected, the high frequency MTF and DQE are degraded substantially at large angles. By contrast, all transfer functions for the back-screen configuration have the advantage of significantly less angular dependence. Using these models, we investigated the

  6. Large area CMOS active pixel sensor x-ray imager for digital breast tomosynthesis: Analysis, modeling, and characterization

    SciTech Connect

    Zhao, Chumin; Kanicki, Jerzy; Konstantinidis, Anastasios C.; Patel, Tushita

    2015-11-15

    Purpose: Large area x-ray imagers based on complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been proposed for various medical imaging applications including digital breast tomosynthesis (DBT). The low electronic noise (50–300 e{sup −}) of CMOS APS x-ray imagers provides a possible route to shrink the pixel pitch to smaller than 75 μm for microcalcification detection and possible reduction of the DBT mean glandular dose (MGD). Methods: In this study, imaging performance of a large area (29 × 23 cm{sup 2}) CMOS APS x-ray imager [Dexela 2923 MAM (PerkinElmer, London)] with a pixel pitch of 75 μm was characterized and modeled. The authors developed a cascaded system model for CMOS APS x-ray imagers using both a broadband x-ray radiation and monochromatic synchrotron radiation. The experimental data including modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE) were theoretically described using the proposed cascaded system model with satisfactory consistency to experimental results. Both high full well and low full well (LFW) modes of the Dexela 2923 MAM CMOS APS x-ray imager were characterized and modeled. The cascaded system analysis results were further used to extract the contrast-to-noise ratio (CNR) for microcalcifications with sizes of 165–400 μm at various MGDs. The impact of electronic noise on CNR was also evaluated. Results: The LFW mode shows better DQE at low air kerma (K{sub a} < 10 μGy) and should be used for DBT. At current DBT applications, air kerma (K{sub a} ∼ 10 μGy, broadband radiation of 28 kVp), DQE of more than 0.7 and ∼0.3 was achieved using the LFW mode at spatial frequency of 0.5 line pairs per millimeter (lp/mm) and Nyquist frequency ∼6.7 lp/mm, respectively. It is shown that microcalcifications of 165–400 μm in size can be resolved using a MGD range of 0.3–1 mGy, respectively. In comparison to a General Electric GEN2 prototype DBT system (at

  7. Characterization of masses in digital breast tomosynthesis: Comparison of machine learning in projection views and reconstructed slices

    SciTech Connect

    Chan, Heang-Ping; Wu Yita; Sahiner, Berkman; Wei, Jun; Helvie, Mark A.; Zhang Yiheng; Moore, Richard H.; Kopans, Daniel B.; Hadjiiski, Lubomir; Way, Ted

    2010-07-15

    Purpose: In digital breast tomosynthesis (DBT), quasi-three-dimensional (3D) structural information is reconstructed from a small number of 2D projection view (PV) mammograms acquired over a limited angular range. The authors developed preliminary computer-aided diagnosis (CADx) methods for classification of malignant and benign masses and compared the effectiveness of analyzing lesion characteristics in the reconstructed DBT slices and in the PVs. Methods: A data set of MLO view DBT of 99 patients containing 107 masses (56 malignant and 51 benign) was collected at the Massachusetts General Hospital with IRB approval. The DBTs were obtained with a GE prototype system which acquired 11 PVs over a 50 deg. arc. The authors reconstructed the DBTs at 1 mm slice interval using a simultaneous algebraic reconstruction technique. The region of interest (ROI) containing the mass was marked by a radiologist in the DBT volume and the corresponding ROIs on the PVs were derived based on the imaging geometry. The subsequent processes were fully automated. For classification of masses using the DBT-slice approach, the mass on each slice was segmented by an active contour model initialized with adaptive k-means clustering. A spiculation likelihood map was generated by analysis of the gradient directions around the mass margin and spiculation features were extracted from the map. The rubber band straightening transform (RBST) was applied to a band of pixels around the segmented mass boundary. The RBST image was enhanced by Sobel filtering in the horizontal and vertical directions, from which run-length statistics texture features were extracted. Morphological features including those from the normalized radial length were designed to describe the mass shape. A feature space composed of the spiculation features, texture features, and morphological features extracted from the central slice alone and seven feature spaces obtained by averaging the corresponding features from three to 19

  8. Ultra-fast digital tomosynthesis reconstruction using general-purpose GPU programming for image-guided radiation therapy.

    PubMed

    Park, Justin C; Park, Sung Ho; Kim, Jin Sung; Han, Youngyih; Cho, Min Kook; Kim, Ho Kyung; Liu, Zhaowei; Jiang, Steve B; Song, Bongyong; Song, William Y

    2011-08-01

    The purpose of this work is to demonstrate an ultra-fast reconstruction technique for digital tomosynthesis (DTS) imaging based on the algorithm proposed by Feldkamp, Davis, and Kress (FDK) using standard general-purpose graphics processing unit (GPGPU) programming interface. To this end, the FDK-based DTS algorithm was programmed "in-house" with C language with utilization of 1) GPU and 2) central processing unit (CPU) cards. The GPU card consisted of 480 processing cores (2 x 240 dual chip) with 1,242 MHz processing clock speed and 1,792 MB memory space. In terms of CPU hardware, we used 2.68 GHz clock speed, 12.0 GB DDR3 RAM, on a 64-bit OS. The performance of proposed algorithm was tested on twenty-five patient cases (5 lung, 5 liver, 10 prostate, and 5 head-and-neck) scanned either with a full-fan or half-fan mode on our cone-beam computed tomography (CBCT) system. For the full-fan scans, the projections from 157.5°-202.5° (45°-scan) were used to reconstruct coronal DTS slices, whereas for the half-fan scans, the projections from both 157.5°-202.5° and 337.5°-22.5° (2 x 45°-scan) were used to reconstruct larger FOV coronal DTS slices. For this study, we chose 45°-scan angle that contained ~80 projections for the full-fan and ~160 projections with 2 x 45°-scan angle for the half-fan mode, each with 1024 x 768 pixels with 32-bit precision. Absolute pixel value differences, profiles, and contrast-to-noise ratio (CNR) calculations were performed to compare and evaluate the images reconstructed using GPU- and CPU-based implementations. The time dependence on the reconstruction volume was also tested with (512 x 512) x 16, 32, 64, 128, and 256 slices. In the end, the GPU-based implementation achieved, at most, 1.3 and 2.5 seconds to complete full reconstruction of 512 x 512 x 256 volume, for the full-fan and half-fan modes, respectively. In turn, this meant that our implementation can process > 13 projections-per-second (pps) and > 18 pps for the full

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  10. 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.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Marshall, N W

    2006-05-21

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

  13. Real-time out-of-plane artifact subtraction tomosynthesis imaging using prior CT for scanning beam digital x-ray system

    SciTech Connect

    Wu, Meng; Fahrig, Rebecca

    2014-11-01

    Purpose: The scanning beam digital x-ray system (SBDX) is an inverse geometry fluoroscopic system with high dose efficiency and the ability to perform continuous real-time tomosynthesis in multiple planes. This system could be used for image guidance during lung nodule biopsy. However, the reconstructed images suffer from strong out-of-plane artifact due to the small tomographic angle of the system. Methods: The authors propose an out-of-plane artifact subtraction tomosynthesis (OPAST) algorithm that utilizes a prior CT volume to augment the run-time image processing. A blur-and-add (BAA) analytical model, derived from the project-to-backproject physical model, permits the generation of tomosynthesis images that are a good approximation to the shift-and-add (SAA) reconstructed image. A computationally practical algorithm is proposed to simulate images and out-of-plane artifacts from patient-specific prior CT volumes using the BAA model. A 3D image registration algorithm to align the simulated and reconstructed images is described. The accuracy of the BAA analytical model and the OPAST algorithm was evaluated using three lung cancer patients’ CT data. The OPAST and image registration algorithms were also tested with added nonrigid respiratory motions. Results: Image similarity measurements, including the correlation coefficient, mean squared error, and structural similarity index, indicated that the BAA model is very accurate in simulating the SAA images from the prior CT for the SBDX system. The shift-variant effect of the BAA model can be ignored when the shifts between SBDX images and CT volumes are within ±10 mm in the x and y directions. The nodule visibility and depth resolution are improved by subtracting simulated artifacts from the reconstructions. The image registration and OPAST are robust in the presence of added respiratory motions. The dominant artifacts in the subtraction images are caused by the mismatches between the real object and the prior CT

  14. Real-time out-of-plane artifact subtraction tomosynthesis imaging using prior CT for scanning beam digital x-ray system

    PubMed Central

    Wu, Meng; Fahrig, Rebecca

    2014-01-01

    Purpose: The scanning beam digital x-ray system (SBDX) is an inverse geometry fluoroscopic system with high dose efficiency and the ability to perform continuous real-time tomosynthesis in multiple planes. This system could be used for image guidance during lung nodule biopsy. However, the reconstructed images suffer from strong out-of-plane artifact due to the small tomographic angle of the system. Methods: The authors propose an out-of-plane artifact subtraction tomosynthesis (OPAST) algorithm that utilizes a prior CT volume to augment the run-time image processing. A blur-and-add (BAA) analytical model, derived from the project-to-backproject physical model, permits the generation of tomosynthesis images that are a good approximation to the shift-and-add (SAA) reconstructed image. A computationally practical algorithm is proposed to simulate images and out-of-plane artifacts from patient-specific prior CT volumes using the BAA model. A 3D image registration algorithm to align the simulated and reconstructed images is described. The accuracy of the BAA analytical model and the OPAST algorithm was evaluated using three lung cancer patients’ CT data. The OPAST and image registration algorithms were also tested with added nonrigid respiratory motions. Results: Image similarity measurements, including the correlation coefficient, mean squared error, and structural similarity index, indicated that the BAA model is very accurate in simulating the SAA images from the prior CT for the SBDX system. The shift-variant effect of the BAA model can be ignored when the shifts between SBDX images and CT volumes are within ±10 mm in the x and y directions. The nodule visibility and depth resolution are improved by subtracting simulated artifacts from the reconstructions. The image registration and OPAST are robust in the presence of added respiratory motions. The dominant artifacts in the subtraction images are caused by the mismatches between the real object and the prior CT

  15. Physical characterization of photon-counting tomosynthesis

    NASA Astrophysics Data System (ADS)

    Berggren, Karl; Lundqvist, Mats; Cederström, Björn; Danielsson, Mats E.; Fredenberg, Erik

    2015-03-01

    Tomosynthesis is emerging as a next generation technology in mammography. Combined with photon-counting detectors with the ability for energy discrimination, a novel modality is enabled — spectral tomosynthesis. Further advantages of photon-counting detectors in the context of tomosynthesis include elimination of electronic noise, efficient scatter rejection (in some geometries) and no lag. Fourier-based linear-systems analysis is a well-established method for optimizing image quality in two-dimensional x-ray systems. The method has been successfully adapted to threedimensional imaging, including tomosynthesis, but several areas need further investigation. This study focuses on two such areas: 1) Adaption of the methodology to photon-counting detectors, and 2) violation of the shift-invariance and stationarity assumptions in non-cylindrical geometries. We have developed a Fourier-based framework to study the image quality in a photon-counting tomosynthesis system, assuming locally linear, stationary, and shift-invariant system response. The framework includes a cascaded-systems model to propagate the modulation-transfer function (MTF) and noise-power spectrum (NPS) through the system. The model was validated by measurements of the MTF and NPS. High degrees of non-shift invariance and non-stationarity were observed, in particular for the depth resolution as the angle of incidence relative the reconstruction plane varied throughout the imaging volume. The largest effects on image quality in a given point in space were caused by interpolation from the inherent coordinate system of the x-rays to the coordinate system that was used for reconstruction. This study is part of our efforts to fully characterize the spectral tomosynthesis system, we intend to extend the model further to include the detective-quantum efficiency, observer modelling, and spectral effects.

  16. Digital Breast Tomosynthesis: Observer Performance of Clustered Microcalcification Detection on Breast Phantom Images Acquired with an Experimental System Using Variable Scan Angles, Angular Increments, and Number of Projection Views

    PubMed Central

    Goodsitt, Mitchell M.; Helvie, Mark A.; Zelakiewicz, Scott; Schmitz, Andrea; Noroozian, Mitra; Paramagul, Chintana; Roubidoux, Marilyn A.; Nees, Alexis V.; Neal, Colleen H.; Carson, Paul; Lu, Yao; Hadjiiski, Lubomir; Wei, Jun

    2014-01-01

    Purpose To investigate the dependence of microcalcification cluster detectability on tomographic scan angle, angular increment, and number of projection views acquired at digital breast tomosynthesis (DBTdigital breast tomosynthesis). Materials and Methods A prototype DBTdigital breast tomosynthesis system operated in step-and-shoot mode was used to image breast phantoms. Four 5-cm-thick phantoms embedded with 81 simulated microcalcification clusters of three speck sizes (subtle, medium, and obvious) were imaged by using a rhodium target and rhodium filter with 29 kV, 50 mAs, and seven acquisition protocols. Fixed angular increments were used in four protocols (denoted as scan angle, angular increment, and number of projection views, respectively: 16°, 1°, and 17; 24°, 3°, and nine; 30°, 3°, and 11; and 60°, 3°, and 21), and variable increments were used in three (40°, variable, and 13; 40°, variable, and 15; and 60°, variable, and 21). The reconstructed DBTdigital breast tomosynthesis images were interpreted by six radiologists who located the microcalcification clusters and rated their conspicuity. Results The mean sensitivity for detection of subtle clusters ranged from 80% (22.5 of 28) to 96% (26.8 of 28) for the seven DBTdigital breast tomosynthesis protocols; the highest sensitivity was achieved with the 16°, 1°, and 17 protocol (96%), but the difference was significant only for the 60°, 3°, and 21 protocol (80%, P < .002) and did not reach significance for the other five protocols (P = .01–.15). The mean sensitivity for detection of medium and obvious clusters ranged from 97% (28.2 of 29) to 100% (24 of 24), but the differences fell short of significance (P = .08 to >.99). The conspicuity of subtle and medium clusters with the 16°, 1°, and 17 protocol was rated higher than those with other protocols; the differences were significant for subtle clusters with the 24°, 3°, and nine protocol and for medium clusters with 24°, 3°, and nine

  17. [Application of algebraic reconstruction technique of multi-source tomosynthesis in dynamic reconstruction].

    PubMed

    Peng, Jiaju; Zhao, Jun

    2011-07-01

    To reduce the motion artifacts, a new scanning configuration is proposed for tomosynthesis in dynamic reconstruction. In this new configuration, multiple x-ray sources are uniformly distributed on the circular scanning trajectory and moving simultaneously. Numerical experiments are performed using two dynamic digital phantoms and algebraic reconstruction technique. The reconstruction images of single-source tomosynthesis and multi-source tomosynthesis are compared and evaluated. The results show that multi-source tomosynthesis could reduce artifacts effectively, thus improving image quality. The advantages of multi-source tomosynthesis in dynamic reconstruction are important to cardiac imaging and respiratory imaging. PMID:22097745

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

    SciTech Connect

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

    2013-08-15

    Purpose: Dual-energy (DE) contrast-enhanced digital mammography (CEDM) uses an iodinated contrast agent in combination with digital mammography (DM) to evaluate lesions on the basis of tumor angiogenesis. In DE imaging, low-energy (LE) and high-energy (HE) images are acquired after contrast administration and their logarithms are subtracted to cancel the appearance of normal breast tissue. Often there is incomplete signal cancellation in the subtracted images, creating a background “clutter” that can impair lesion detection. This is the second component of a two-part report on anatomical noise in CEDM. In Part I the authors characterized the anatomical noise for single-energy (SE) temporal subtraction CEDM by a power law, with model parameters α and β. In this work the authors quantify the anatomical noise in DE CEDM clinical images and compare this with the noise in SE CEDM. The influence on the anatomical noise of the presence of iodine in the breast, the timing of imaging postcontrast administration, and the x-ray energy used for acquisition are each evaluated.Methods: The power law parameters, α and β, were measured from unprocessed LE and HE images and from DE subtracted images to quantify the anatomical noise. A total of 98 DE CEDM cases acquired in a previous clinical pilot study were assessed. Conventional DM images from 75 of the women were evaluated for comparison with DE CEDM. The influence of the imaging technique on anatomical noise was determined from an analysis of differences between the power law parameters as measured in DM, LE, HE, and DE subtracted images for each subject.Results: In DE CEDM, weighted image subtraction lowers β to about 1.1 from 3.2 and 3.1 in LE and HE unprocessed images, respectively. The presence of iodine has a small but significant effect in LE images, reducing β by about 0.07 compared to DM, with α unchanged. Increasing the x-ray energy, from that typical in DM to a HE beam, significantly decreases α by about 2

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

    SciTech Connect

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

    2013-05-15

    Purpose: The use of an intravenously injected iodinated contrast agent could help increase the sensitivity of digital mammography by adding information on tumor angiogenesis. Two approaches have been made for clinical implementation of contrast-enhanced digital mammography (CEDM), namely, single-energy (SE) and dual-energy (DE) imaging. In each technique, pairs of mammograms are acquired, which are then subtracted with the intent to cancel the appearance of healthy breast tissue to permit sensitive detection and specific characterization of lesions. Patterns of contrast agent uptake in the healthy parenchyma, and uncanceled signal from background tissue create a 'clutter' that can mask or mimic an enhancing lesion. This type of 'anatomical noise' is often the limiting factor in lesion detection tasks, and thus, noise quantification may be useful for cascaded systems analysis of CEDM and for phantom development. In this work, the authors characterize the anatomical noise in CEDM clinical images and the authors evaluate the influence of the x-ray energy used for acquisition, the presence of iodine in the breast, and the timing of imaging postcontrast administration on anatomical noise. The results are presented in a two-part report, with SE CEDM described here, and DE CEDM in Part II. Methods: A power law is used to model anatomical noise in CEDM images. The exponent, {beta}, which describes the anatomical structure, and the constant {alpha}, which represents the magnitude of the noise, are determined from Wiener spectra (WS) measurements on images. A total of 42 SE CEDM cases from two previous clinical pilot studies are assessed. The parameters {alpha} and {beta} are measured both from unprocessed images and from subtracted images. Results: Consistent results were found between the two SE CEDM pilot studies, where a significant decrease in {beta} from a value of approximately 3.1 in the unprocessed images to between about 1.1 and 1.8 in the subtracted images was

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

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

    PubMed

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

    2005-09-01

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

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

    PubMed

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

    2012-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    PubMed

    Fahrig, R; Yaffe, M J

    1994-09-01

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

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

    SciTech Connect

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

    2010-12-15

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

  6. SU-E-J-02: 4D Digital Tomosynthesis Based On Algebraic Image Reconstruction and Total-Variation Minimization for the Improvement of Image Quality

    SciTech Connect

    Kim, D; Kang, S; Kim, T; Suh, T; Kim, S

    2014-06-01

    Purpose: In this paper, we implemented the four-dimensional (4D) digital tomosynthesis (DTS) imaging based on algebraic image reconstruction technique and total-variation minimization method in order to compensate the undersampled projection data and improve the image quality. Methods: The projection data were acquired as supposed the cone-beam computed tomography system in linear accelerator by the Monte Carlo simulation and the in-house 4D digital phantom generation program. We performed 4D DTS based upon simultaneous algebraic reconstruction technique (SART) among the iterative image reconstruction technique and total-variation minimization method (TVMM). To verify the effectiveness of this reconstruction algorithm, we performed systematic simulation studies to investigate the imaging performance. Results: The 4D DTS algorithm based upon the SART and TVMM seems to give better results than that based upon the existing method, or filtered-backprojection. Conclusion: The advanced image reconstruction algorithm for the 4D DTS would be useful to validate each intra-fraction motion during radiation therapy. In addition, it will be possible to give advantage to real-time imaging for the adaptive radiation therapy. This research was supported by Leading Foreign Research Institute Recruitment Program (Grant No.2009-00420) and Basic Atomic Energy Research Institute (BAERI); (Grant No. 2009-0078390) through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT and Future Planning (MSIP)

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

    SciTech Connect

    Pedersen, Kristin; Landmark, Ingrid Dypvik

    2009-12-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    Contrast media, such as iodine and gadolinium, are generally used in digital subtraction mammography to enhance the contrast between target and background materials. In digital subtraction mammography, where one image (with contrast medium) is subtracted from another (anatomical background) to facilitate visualization of the tumor structure, tumors can be more easily distinguished after the injection of a contrast medium. In order to have more an effective method to increase the contrast-to-noise ratio (CNR), we applied a projection-based energy-weighting method. The purpose of this study is to demonstrate the feasibility of using the projection-based energy-weighting method in digital subtraction mammography. Unlike some other previous studies, we applied the projection-based energy-weighting method to more practical mammography conditions by using the Monte Carlo method to simulate four different iodine solutions embedded in a breast phantom comprised of 50% adipose and 50% glandular tissues. We also considered an optimal tube voltage and anode/filter combination in digital iodine contrast media mammography in order to maximize the figure-of-merit (FOM). The simulated source energy was from 20 to 45 keV to prevent electronic noise and include the k-edge energy of iodine (33.2 keV). The results showed that the projection-based energy-weighting improved the CNR by factors of 1.05-1.86 compared to the conventionally integrated images. Consequently, the CNR of digital subtraction mammography images can be improved by using projection-based energy-weighting with photon-counting detectors.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

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

  14. 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.

  15. Evaluating the sensitivity of the optimization of acquisition geometry to the choice of reconstruction algorithm in digital breast tomosynthesis through a simulation study

    NASA Astrophysics Data System (ADS)

    Zeng, Rongping; Park, Subok; Bakic, Predrag; Myers, Kyle J.

    2015-02-01

    Due to the limited number of views and limited angular span in digital breast tomosynthesis (DBT), the acquisition geometry design is an important factor that affects the image quality. Therefore, intensive studies have been conducted regarding the optimization of the acquisition geometry. However, different reconstruction algorithms were used in most of the reported studies. Because each type of reconstruction algorithm can provide images with its own image resolution, noise properties and artifact appearance, it is unclear whether the optimal geometries concluded for the DBT system in one study can be generalized to the DBT systems with a reconstruction algorithm different to the one applied in that study. Hence, we investigated the effect of the reconstruction algorithm on the optimization of acquisition geometry parameters through carefully designed simulation studies. Our results show that using various reconstruction algorithms, including the filtered back-projection, the simultaneous algebraic reconstruction technique, the maximum-likelihood method and the total-variation regularized least-square method, gave similar performance trends for the acquisition parameters for detecting lesions. The consistency of system ranking indicates that the choice of the reconstruction algorithm may not be critical for DBT system geometry optimization.

  16. Evaluation of the image quality in digital breast tomosynthesis (DBT) employed with a compressed-sensing (CS)-based reconstruction algorithm by using the mammographic accreditation phantom

    NASA Astrophysics Data System (ADS)

    Park, Yeonok; Cho, Heemoon; Je, Uikyu; Cho, Hyosung; Park, Chulkyu; Lim, Hyunwoo; Kim, Kyuseok; Kim, Guna; Park, Soyoung; Woo, Taeho; Choi, Sungil

    2015-12-01

    In this work, we have developed a prototype digital breast tomosynthesis (DBT) system which mainly consists of an x-ray generator (28 kVp, 7 mA s), a CMOS-type flat-panel detector (70-μm pixel size, 230.5×339 mm2 active area), and a rotational arm to move the x-ray generator in an arc. We employed a compressed-sensing (CS)-based reconstruction algorithm, rather than a common filtered-backprojection (FBP) one, for more accurate DBT reconstruction. Here the CS is a state-of-the-art mathematical theory for solving the inverse problems, which exploits the sparsity of the image with substantially high accuracy. We evaluated the reconstruction quality in terms of the detectability, the contrast-to-noise ratio (CNR), and the slice-sensitive profile (SSP) by using the mammographic accreditation phantom (Model 015, CIRS Inc.) and compared it to the FBP-based quality. The CS-based algorithm yielded much better image quality, preserving superior image homogeneity, edge sharpening, and cross-plane resolution, compared to the FBP-based one.

  17. Compressed-sensing (CS)-based digital breast tomosynthesis (DBT) reconstruction for low-dose, accurate 3D breast X-ray imaging

    NASA Astrophysics Data System (ADS)

    Park, Yeonok; Cho, Hyosung; Je, Uikyu; Hong, Daeki; Lee, Minsik; Park, Chulkyu; Cho, Heemoon; Choi, Sungil; Koo, Yangseo

    2014-08-01

    In practical applications of three-dimensional (3D) tomographic techniques, such as digital breast tomosynthesis (DBT), computed tomography (CT), etc., there are often challenges for accurate image reconstruction from incomplete data. In DBT, in particular, the limited-angle and few-view projection data are theoretically insufficient for exact reconstruction; thus, the use of common filtered-backprojection (FBP) algorithms leads to severe image artifacts, such as the loss of the average image value and edge sharpening. One possible approach to alleviate these artifacts may employ iterative statistical methods because they potentially yield reconstructed images that are in better accordance with the measured projection data. In this work, as another promising approach, we investigated potential applications to low-dose, accurate DBT imaging with a state-of-the-art reconstruction scheme based on compressed-sensing (CS) theory. We implemented an efficient CS-based DBT algorithm and performed systematic simulation works to investigate the imaging characteristics. We successfully obtained DBT images of substantially very high accuracy by using the algorithm and expect it to be applicable to developing the next-generation 3D breast X-ray imaging system.

  18. Investigating the feasibility of using partial least squares as a method of extracting salient information for the evaluation of digital breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Zhang, George Z.; Myers, Kyle J.; Park, Subok

    2013-03-01

    Digital breast tomosynthesis (DBT) has shown promise for improving the detection of breast cancer, but it has not yet been fully optimized due to a large space of system parameters to explore. A task-based statistical approach1 is a rigorous method for evaluating and optimizing this promising imaging technique with the use of optimal observers such as the Hotelling observer (HO). However, the high data dimensionality found in DBT has been the bottleneck for the use of a task-based approach in DBT evaluation. To reduce data dimensionality while extracting salient information for performing a given task, efficient channels have to be used for the HO. In the past few years, 2D Laguerre-Gauss (LG) channels, which are a complete basis for stationary backgrounds and rotationally symmetric signals, have been utilized for DBT evaluation2, 3 . But since background and signal statistics from DBT data are neither stationary nor rotationally symmetric, LG channels may not be efficient in providing reliable performance trends as a function of system parameters. Recently, partial least squares (PLS) has been shown to generate efficient channels for the Hotelling observer in detection tasks involving random backgrounds and signals.4 In this study, we investigate the use of PLS as a method for extracting salient information from DBT in order to better evaluate such systems.

  19. Digital tomosynthesis (DTS) with a Circular X-ray tube: Its image reconstruction based on total-variation minimization and the image characteristics

    NASA Astrophysics Data System (ADS)

    Park, Y. O.; Hong, D. K.; Cho, H. S.; Je, U. K.; Oh, J. E.; Lee, M. S.; Kim, H. J.; Lee, S. H.; Jang, W. S.; Cho, H. M.; Choi, S. I.; Koo, Y. S.

    2013-09-01

    In this paper, we introduce an effective imaging system for digital tomosynthesis (DTS) with a circular X-ray tube, the so-called circular-DTS (CDTS) system, and its image reconstruction algorithm based on the total-variation (TV) minimization method for low-dose, high-accuracy X-ray imaging. Here, the X-ray tube is equipped with a series of cathodes distributed around a rotating anode, and the detector remains stationary throughout the image acquisition. We considered a TV-based reconstruction algorithm that exploited the sparsity of the image with substantially high image accuracy. We implemented the algorithm for the CDTS geometry and successfully reconstructed images of high accuracy. The image characteristics were investigated quantitatively by using some figures of merit, including the universal-quality index (UQI) and the depth resolution. For selected tomographic angles of 20, 40, and 60°, the corresponding UQI values in the tomographic view were estimated to be about 0.94, 0.97, and 0.98, and the depth resolutions were about 4.6, 3.1, and 1.2 voxels in full width at half maximum (FWHM), respectively. We expect the proposed method to be applicable to developing a next-generation dental or breast X-ray imaging system.

  20. Follow-up of endovascular aortic aneurysm repair: Preliminary validation of digital tomosynthesis and contrast enhanced ultrasound in detection of medium- to long-term complications

    PubMed Central

    Mazzei, Maria Antonietta; Guerrini, Susanna; Mazzei, Francesco Giuseppe; Cioffi Squitieri, Nevada; Notaro, Dario; de Donato, Gianmarco; Galzerano, Giuseppe; Sacco, Palmino; Setacci, Francesco; Volterrani, Luca; Setacci, Carlo

    2016-01-01

    AIM: To validate the feasibility of digital tomosynthesis of the abdomen (DTA) combined with contrast enhanced ultrasound (CEUS) in assessing complications after endovascular aortic aneurysm repair (EVAR) by using computed tomography angiography (CTA) as the gold standard. METHODS: For this prospective study we enrolled 163 patients (123 men; mean age, 65.7 years) referred for CTA for EVAR follow-up. CTA, DTA and CEUS were performed at 1 and 12 mo in all patients, with a maximum time interval of 2 d. RESULTS: Among 163 patients 33 presented complications at CTA. DTA and CTA correlated for the presence of complications in 32/33 (96.96%) patients and for the absence of complications in 127/130 (97.69%) patients; the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of DTA were 97%, 98%, 91%, 99%, and 98%, respectively. CEUS and CTA correlated for the presence of complications in 19/33 (57.57%) patients and for the absence of complications in 129/130 (99.23%) patients; the sensitivity, specificity, PPV, NPV and accuracy of CEUS were 58%, 99%, 95%, 90%, and 91%, respectively. Sensitivity, specificity and accuracy of combining DTA and CEUS together in detecting EVAR complications were 77%, 98% and 95%, respectively. CONCLUSION: Combining DTA and CEUS in EVAR follow-up has the potential to limit the use of CTA only in doubtful cases. PMID:27247719