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Sökning: WFRF:(Timberg Pontus)

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1.
  • Dustler, Magnus, et al. (författare)
  • The characteristics of malignant breast tumors imaged using a prototype mechanical imaging system as an adjunct to mammography
  • 2016
  • Ingår i: Breast Imaging : 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings - 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783319415451 - 9783319415468 ; 9699, s. 282-288
  • Konferensbidrag (refereegranskat)abstract
    • Breast cancer is diagnosed by a combination of modalities. Measuring the elasto-mechanical properties of suspicious lesions, by e.g. ultrasound elastography, can help differentiate malignant from benign findings. Using a prototype Mechanical Imaging (MI) system as an adjunct to mammography, the aim of this study was to characterize tumors using MI and compare the readings to those from the contralateral breast. Thirteen bilateral MI sets from women with malignant breast lesions were included in this study, drawn from a larger set of 155 women recalled from screening. The results showed that mean lesion pressure was significantly greater than the mean pressure of the corresponding breast, 7.5 ± 7.0 kPa compared to 2.5 ± 1.6 kPa (P = 0.01). There was no evidence for a difference in mean pressure or standard deviation of the MI image between symptomatic and contralateral asymptomatic breasts (P = 0.24 and 0.68). The results support that it is possible to use MI to distinguish malignant cancers from normal breast tissue. Still, further investigations of the characteristics of benign lesions are necessary to ascertain the usefulness of the system.
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2.
  • Timberg, Pontus, et al. (författare)
  • Breast density assessment using breast tomosynthesis images
  • 2016
  • Ingår i: Breast Imaging : 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings - 13th International Workshop, IWDM 2016, Malmö, Sweden, June 19-22, 2016, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783319415451 - 9783319415468 ; 9699, s. 197-202
  • Konferensbidrag (refereegranskat)abstract
    • In this work we evaluate an approach for breast density assessment of digital breast tomosynthesis (DBT) data using the central projection image. A total of 348 random cases (both FFDM CC and MLO views and DBT MLO views) were collected using a Siemens Mammomat Inspiration tomosynthesis unit at Unilabs, Malmö. The cases underwent both BI-RADS 5th Edition labeling by radiologists and automated volumetric breast density analysis (VBDA) by an algorithm. Preliminary results showed an observed agreement of 70% (weighted Kappa, κ = 0.73) between radiologists and VBDA using FFDM images and 63% (κ = 0.62) for radiologists and VBDA using DBT images. Comparison between densities for FFDM and DBT resulted in high correlation (r = 0.94) and an observed agreement of 72% (κ = 0.76). The automated analysis is a promising approach using low dose central projection DBT images in order to get radiologist- like density ratings similar to results obtained from FFDM.
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3.
  • Andersson, Ingvar, et al. (författare)
  • Breast tomosynthesis and digital mammography: a comparison of breast cancer visibility and BIRADS classification in a population of cancers with subtle mammographic findings.
  • 2008
  • Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 18, s. 2817-2825
  • Tidskriftsartikel (refereegranskat)abstract
    • The main purpose was to compare breast cancer visibility in one-view breast tomosynthesis (BT) to cancer visibility in one- or two-view digital mammography (DM). Thirty-six patients were selected on the basis of subtle signs of breast cancer on DM. One-view BT was performed with the same compression angle as the DM image in which the finding was least/not visible. On BT, 25 projections images were acquired over an angular range of 50 degrees, with double the dose of one-view DM. Two expert breast imagers classified one- and two-view DM, and BT findings for cancer visibility and BIRADS cancer probability in a non-blinded consensus study. Forty breast cancers were found in 37 breasts. The cancers were rated more visible on BT compared to one-view and two-view DM in 22 and 11 cases, respectively, (p < 0.01 for both comparisons). Comparing one-view DM to one-view BT, 21 patients were upgraded on BIRADS classification (p < 0.01). Comparing two-view DM to one-view BT, 12 patients were upgraded on BIRADS classification (p < 0.01). The results indicate that the cancer visibility on BT is superior to DM, which suggests that BT may have a higher sensitivity for breast cancer detection.
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4.
  • Ba, Alexandre, et al. (författare)
  • Inter-laboratory comparison of channelized hotelling observer computation
  • 2018
  • Ingår i: Medical Physics. - : Wiley. - 0094-2405 .- 2473-4209. ; 45:7, s. 3019-3030
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: The task-based assessment of image quality using model observers is increasingly used for the assessment of different imaging modalities. However, the performance computation of model observers needs standardization as well as a well-established trust in its implementation methodology and uncertainty estimation. The purpose of this work was to determine the degree of equivalence of the channelized Hotelling observer performance and uncertainty estimation using an intercomparison exercise. Materials and Methods: Image samples to estimate model observer performance for detection tasks were generated from two-dimensional CT image slices of a uniform water phantom. A common set of images was sent to participating laboratories to perform and document the following tasks: (a) estimate the detectability index of a well-defined CHO and its uncertainty in three conditions involving different sized targets all at the same dose, and (b) apply this CHO to an image set where ground truth was unknown to participants (lower image dose). In addition, and on an optional basis, we asked the participating laboratories to (c) estimate the performance of real human observers from a psychophysical experiment of their choice. Each of the 13 participating laboratories was confidentially assigned a participant number and image sets could be downloaded through a secure server. Results were distributed with each participant recognizable by its number and then each laboratory was able to modify their results with justification as model observer calculation are not yet a routine and potentially error prone. Results: Detectability index increased with signal size for all participants and was very consistent for 6 mm sized target while showing higher variability for 8 and 10 mm sized target. There was one order of magnitude between the lowest and the largest uncertainty estimation. Conclusions: This intercomparison helped define the state of the art of model observer performance computation and with thirteen participants, reflects openness and trust within the medical imaging community. The performance of a CHO with explicitly defined channels and a relatively large number of test images was consistently estimated by all participants. In contrast, the paper demonstrates that there is no agreement on estimating the variance of detectability in the training and testing setting.
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5.
  • Bakic, Predrag R., et al. (författare)
  • Artifact reduction in simultaneous tomosynthesis and mechanical imaging of the breast
  • 2019
  • Ingår i: Medical Imaging 2019 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 9781510625433 ; 10948
  • Konferensbidrag (refereegranskat)abstract
    • Mechanical imaging (MI) uses a pressure sensor array to estimate the stiffness of lesions. Recent clinical studies have suggested that MI combined with digital mammography may reduce false positive findings and negative biopsies by over 30%. Digital breast tomosynthesis (DBT) has been adopted progressively in cancer screening. The tomographic nature of DBT improves lesion visibility by reducing tissue overlap in reconstructed images. For maximum benefit, DBT and MI data should be acquired simultaneously; however, that arrangement produces visible artifacts in DBT images due to the presence of the MI sensor array. We propose a method for reducing artifacts during the DBT image reconstruction. We modified the parameters of a commercial DBT reconstruction engine and investigated the conspicuity of artifacts in the resultant images produced with different sensor orientations. The method was evaluated using a physical anthropomorphic phantom imaged on top of the sensor. Visual assessment showed a reduction of artifacts. In a quantitative test, we calculated the artifact spread function (ASF), and compared the ratio of the mean ASF values between the proposed and conventional reconstruction (termed ASF ratio, RASF). We obtained a mean RASF of 2.74, averaged between two analyzed sensor orientations (45° and 90°). The performance varied with the orientation and the type of sensor structures causing the artifacts. RASF for wide connection lines was larger at 45° than at 90° (5.15 vs. 1.00, respectively), while for metallic contacts RASF was larger at 90° than at 45° (3.31 vs. 2.21, respectively). Future work will include a detailed quantitative assessment, and further method optimization in virtual clinical trials.
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6.
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7.
  • Diaz, Ivan, et al. (författare)
  • Derivation of an Observer Model Adapted to Irregular Signals Based on Convolution Channels
  • 2015
  • Ingår i: IEEE Transactions on Medical Imaging. - 1558-254X. ; 34:7, s. 1428-1435
  • Tidskriftsartikel (refereegranskat)abstract
    • Anthropomorphic model observers are mathe-matical algorithms which are applied to images with the ultimate goal of predicting human signal detection and classification accuracy across varieties of backgrounds, image acquisitions and display conditions. A limitation of current channelized model observers is their inability to handle irregularly-shaped signals, which are common in clinical images, without a high number of directional channels. Here, we derive a new linear model observer based on convolution channels which we refer to as the "Filtered Channel observer" (FCO), as an extension of the channelized Hotelling observer (CHO) and the nonprewhitening with an eye filter (NPWE) observer. In analogy to the CHO, this linear model observer can take the form of a single template with an external noise term. To compare with human observers, we tested signals with irregular and asymmetrical shapes spanning the size of lesions down to those of microcalfications in 4-AFC breast tomosynthesis detection tasks, with three different contrasts for each case. Whereas humans uniformly outperformed conventional CHOs, the FCO observer outperformed humans for every signal with only one exception. Additive internal noise in the models allowed us to degrade model performance and match human performance. We could not match all the human performances with a model with a single internal noise component for all signal shape, size and contrast conditions. This suggests that either the internal noise might vary across signals or that the model cannot entirely capture the human detection strategy. However, the FCO model offers an efficient way to apprehend human observer performance for a non-symmetric signal.
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8.
  • Dustler, Magnus, et al. (författare)
  • A Study of the Feasibility of using slabbing to reduce Tomosynthesis Review Time
  • 2013
  • Ingår i: Medical Imaging 2013: Image Perception, Observer Performance, And Technology Assessment. - : SPIE. - 0277-786X .- 1996-756X. ; 8673, s. 86731-86731
  • Konferensbidrag (refereegranskat)abstract
    • This study aimed to investigate whether decreasing the amount of slices in breast tomosynthesis (BT) image volumes reduce reading time. BT slices were combined into so-called slabs, by reconstructing thin slices and merging them into thicker slabs. Sets of slabs where created from 35 clinical BT volumes with malignant or benignant findings and from 50 BT volumes drawn from screening sets (without any prior review). The image sets were reviewed in two separate sessions while the review time was recorded. A total of five experienced radiologists were employed for the image review. Additionally a VGA study was performed to compare slabbed images with the originals in order to ensure that the image quality was not significantly degraded. One set of 27 pathological cases (13 masses and 14 microcalcification clusters) and one of 22 subtle lesions that had been missed on digital mammography but detected on BT were presented to an experienced radiologist and 2 medical physicists who rated the quality of the slabbed versions relative to the originals. The study could find no significant degradation in image quality when using 2 mm slabs instead of 1 mm slices. There was no significant decrease in reading time on clinical cases (P=.133), but on screening images there was a significant decrease of 7.7 +/- 9.6 s from an average level of 32.2 +/- 14.5 s (P<.0001). This suggests that increasing slab thickness can reduce the time radiologists spend studying normal images by 20%.
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9.
  • Dustler, Magnus, et al. (författare)
  • Application of the fractal Perlin noise algorithm for the generation of simulated breast tissue
  • 2015
  • Ingår i: Medical Imaging 2015: Physics of Medical Imaging. - : SPIE. - 1996-756X .- 0277-786X. ; 9412, s. 94123-94123
  • Konferensbidrag (refereegranskat)abstract
    • Software breast phantoms are increasingly seeing use in preclinical validation of breast image acquisition systems and image analysis methods. Phantom realism has been proven sufficient for numerous specific validation tasks. A challenge is the generation of suitably realistic small-scale breast structures that could further improve the quality of phantom images. Power law noise follows the noise power characteristics of breast tissue, but may not sufficiently represent certain (e.g., non-Gaussian) properties seen in clinical breast images. The purpose of this work was to investigate the utility of fractal Perlin noise in generating more realistic breast tissue through investigation of its power spectrum and visual characteristics. Perlin noise is an algorithm that creates smoothly varying random structures of an arbitrary frequency. Through the use of a technique known as fractal noise or fractional Brownian motion (fBm), octaves of noise with different frequency are combined to generate coherent noise with a broad frequency range. fBm is controlled by two parameters - lacunarity and persistence - related to the frequency and amplitude of successive octaves, respectively. Average noise power spectra were calculated and beta parameters estimated in sample volumes of fractal Perlin noise with different combinations of lacunarity and persistence. Certain combinations of parameters resulted in noise volumes with beta values between 2 and 3, corresponding to reported measurements in real breast tissue. Different combinations of parameters resulted in different visual appearances. In conclusion, Perlin noise offers a flexible tool for generating breast tissue with realistic properties.
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10.
  • Dustler, Magnus, et al. (författare)
  • Can mechanical imaging increase the specificity of mammography screening?
  • 2017
  • Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 27:8, s. 3217-3225
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: This study aimed to investigate the effects of adding adjunct mechanical imaging to mammography breast screening. We hypothesized that mechanical imaging could detect increased local pressure caused by both malignant and benign breast lesions and that a pressure threshold for malignancy could be established. The impact of this on breast screening was investigated with regard to reductions in recall and biopsy rates. Methods: 155 women recalled from breast screening were included in the study, which was approved by the regional ethical review board (dnr 2013/620). Mechanical imaging readings were acquired of the symptomatic breast. The relative mean pressure on the suspicious area (RMPA) was defined and a threshold for malignancy was established. Results: Biopsy-proven invasive cancers had a median RMPA of 3.0 (interquartile range (IQR) = 3.7), significantly different from biopsy-proven benign at 1.3 (IQR = 1.0) and non-biopsied cases at 1.0 (IQR = 1.3) (P < 0.001). The lowest RMPA for invasive cancer was 1.4, with 23 biopsy-proven benign and 33 non-biopsied cases being below this limit. Had these women not been recalled, recall rates would have been reduced by 36% and biopsy rates by 32%. Conclusions: If implemented in a screening situation, this may substantially lower the number of false positives. Key Points: • Mechanical imaging is used as an adjunct to mammography in breast screening.• A threshold pressure can be established for malignant breast cancer.• Recalls and biopsies can be substantially reduced.
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11.
  • Dustler, Magnus, et al. (författare)
  • Distribution of pressure on the breast in mammography using flexible and rigid compression plates : implications on patient handling
  • 2021
  • Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 62:12, s. 1583-1591
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Breast compression in mammography is important but is a source of discomfort and has been linked to screening non-attendance. Reducing compression has little effect on breast thickness, and likely little effect on image quality, due to force being absorbed in the stiff juxta thoracic area instead of in the central breast. Purpose: To investigate whether a flexible compression plate can redistribute force to the central breast and whether this affects perceived pain. Material and Methods: Twenty-eight women recalled from mammography screening were compressed with flexible and rigid plates while retaining force and positioning, 15 in the craniocaudal (CC) view and 13 in the mediolateral oblique (MLO) view. Pressure distribution was continuously measured using pressure sensors. Results: The flexible plate showed greater mean breast pressure in both views: 2.8 versus 2.3 kPa for CC (confidence interval [CI] = 0.2–0.8) and 1.0 versus 0.5 kPa for MLO (CI = 0.2–0.6). The percentage of applied force distributed to the breast was significantly higher with the flexible plate, both on CC (36% vs. 22%, CI = 1–11) and MLO (30% vs. 14%, CI = 4–13). Conclusion: The flexible plate redistributes pressure to the central breast, achieving a better compression, particularly in the MLO view, though much applied force is still applied to the juxta thoracic region.
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12.
  • Dustler, Magnus, et al. (författare)
  • VOLUMETRIC LOCALISATION OF DENSE BREAST TISSUE USING BREAST TOMOSYNTHESIS DATA.
  • 2016
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420.
  • Tidskriftsartikel (refereegranskat)abstract
    • This study attempted to use combined data from reconstructed digital breast tomosynthesis (DBT) volumes and density estimation of projection images to localise dense tissue inside the breast, using the assumption that the breast can be treated as consisting of only two types of tissue: fibroglandular (dense) and adipose (fatty). To be able to verify results, software breast phantoms generated using fractal Perlin noise were employed. Projection images were created using the PENELOPE Monte Carlo package. Dense tissue volume was estimated from the central projection image. The density image was used to determine the number of dense voxels at each pixel location, which were then placed using the DBT image as a template. The method proved capable of accurately determining the composition of 75±5 % of voxels.
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13.
  • Förnvik, Daniel, et al. (författare)
  • A human observer study for evaluation and optimization of reconstruction methods in breast tomosynthesis using clinical cases
  • 2011
  • Ingår i: Medical Imaging 2011: Physics of Medical Imaging. - : SPIE. - 0277-786X .- 1996-756X. ; 7961, s. 79615-79615
  • Konferensbidrag (refereegranskat)abstract
    • In breast tomosynthesis1 (BT) a number of 2D projection images are acquired from different angles along a limited arc. The imaged breast volume is reconstructed from the projection images, providing 3D information. The purpose of the study was to investigate and optimize different reconstruction methods for BT in terms of image quality using human observers viewing clinical cases. Sixty-six cases with suspected masses and calcifications were collected from 55 patients. Four different reconstructions of each image set were evaluated by four observers (two experienced radiologists, two experienced medical physicists): filtered back projection (FBP), iterative adapted FBP (iFBP) and two ML-convex iterative algorithm (MLCI) reconstructions (8 and 10 iterations) that differed in noise level and contrast of clinical details. Representation of masses and microcalcifications was evaluated. The structures were rated according to the overall appearance in a rank-order study. The differently reconstructed images of the same structure were displayed side by side in random order. The observers were forced to rank the order of the different reconstructed images and their proportions at each rank were scored. The results suggest that even though the FBP contains most noise its reconstructions are considered best overall, followed by iFBP, which contains least noise. In both FBP and iFBP methods the sharp borders and mass speculations were better represented than in iterative reconstructions while out-of-plane artifacts were better suppressed in the latter. However, in clinical practice the differences between the reconstructions may be considered negligible.
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14.
  • Förnvik, Daniel, et al. (författare)
  • Breast tomosynthesis: Accuracy of tumor measurement compared with digital mammography and ultrasonography.
  • 2010
  • Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 51, s. 240-247
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Mammographic tumor size measurement can be difficult because breast structures are superimposed onto a two-dimensional (2D) plane, potentially obscuring the tumor outline. Breast tomosynthesis (BT) is a 3D X-ray imaging technique in which low-dose images are acquired over a limited angular range at a total dose comparable to digital mammography (DM). These low-dose images are used to mathematically reconstruct a 3D image volume of the breast, thus reducing the problem of superimposed tissue. Purpose: To investigate whether breast cancer size can be more accurately assessed with breast tomosynthesis than with digital mammography and ultrasonography (US), by reducing the disturbance effect of the projected anatomy. Material and Methods: A prototype BT system was used. The main inclusion criterion for BT examination was subtle but suspicious findings of breast cancer on 2D mammography. Sixty-two women with 73 breast cancers were included. BT, DM, and US sizes were measured independently by experienced radiologists without knowledge of the pathology results, which were used as reference. Results: The tumor outline could be determined in significantly more cases with BT (63) and US (60) than DM (49). BT and US size correlated well with pathology (R=0.86 and R=0.85, respectively), and significantly better than DM size (R=0.71). Accordingly, staging was significantly more accurate with BT than with DM. Conclusion: The study indicates that BT is superior to DM in the assessment of breast tumor size and stage.
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15.
  • Förnvik, Daniel, et al. (författare)
  • ESTIMATES OF BREAST CANCER GROWTH RATE FROM MAMMOGRAMS AND ITS RELATION TO TUMOUR CHARACTERISTICS.
  • 2016
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169, s. 151-157
  • Tidskriftsartikel (refereegranskat)abstract
    • This study aimed to investigate the growth rate of 31 consecutive invasive breast cancers based on volume measures on at least two serial mammograms and its relation to histopathological findings. The average tumour volume-doubling time in all invasive breast cancer subtypes was 282 d (range 46-749 d). Grade III breast cancers had a significantly shorter average tumour volume-doubling time of 105 d (range 46-157 d) compared with Grade I and II tumours (average of 296 d, range 147-531 d and average of 353 d, range 139-749 d, respectively) (p = 0.002). Multiple linear regression identified that tumour volume-doubling time was positively associated with patient age, histological grade and progesterone receptor expression and inversely associated with axillary lymph node involvement, human epidermal growth factor receptor 2 and Ki-67 expression (p < 0.001). In conclusion, tumour volume-doubling time as estimated on serial mammography may provide important prognostic information relevant for clinical decision-making.
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16.
  • Förnvik, Daniel, et al. (författare)
  • Pressure distribution in mammography: compression of breasts with malignant tumor masses
  • 2013
  • Ingår i: Medical Imaging 2013: Physics of Medical Imaging. - : SPIE. - 1996-756X .- 0277-786X. ; 8668, s. 86684-86684
  • Konferensbidrag (refereegranskat)abstract
    • The pressure distribution over a compressed breast is in general heterogeneous. In this study we investigated the pressure distribution over compressed breasts with tumor masses. Twenty-two women either recalled for work-up of findings suspicious for breast cancer in the screening program or with clinically suspected findings were included in the study. Twenty-one lesions turned out to be malignant and one benign. The distribution of compression pressure was measured using thin FSR (Force Sensing Resistor) pressure sensors attached to the compression plate. The pressure over the breast was ascertained by acquiring an x-ray image of the compressed breast with the pressure sensors present. The pressure data and the mammogram were used to create a composite image with pressure data displayed as a color overlay. The malignant tumor area generally matched an elevated pressure area and this pressure was generally higher than the pressure over surrounding parenchyma. In 11 out of 22 (50%) subjects the maximum pressure over the breast was located over the tumor. Only 4 out of 22 (18%) masses had a lower tumor mean pressure compared to the mean pressure over the breast (including one small < 10 mm tumor and one benign structure). The results suggest that tumors are stiffer, thus, absorbing more pressure compared to the surrounding parenchyma and that this property can be quantified. Refined pressure techniques could possibly be used to demonstrate the relative elasticity distribution in breast tissue, which might provide valuable differential diagnostic information.
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17.
  • Förnvik, Daniel, et al. (författare)
  • THE EFFECT OF REDUCED BREAST COMPRESSION IN BREAST TOMOSYNTHESIS: HUMAN OBSERVER STUDY USING CLINICAL CASES.
  • 2010
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; Apr 7, s. 118-123
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to investigate whether the compression force used with conventional mammography can be reduced with breast tomosynthesis (BT), without adversely affecting the visualisation of normal and pathological structures. Forty-five women were examined with BT using full (same as for 2D mammography) and half compression force. Both examinations were performed with the same acquisition parameters. A total of 103 paired structure images were evaluated according to specified image quality criteria. Three experienced radiologists participated in the study. They had to make a forced choice, i.e. choose the image they felt best fulfilled the image quality criteria. The results showed no evident difference in the image quality, indicating that BT may be performed with substantially less compression force compared with 2D mammography. A majority of the examined women felt that half compression was more comfortable than full compression.
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18.
  • Förnvik, Hannie, et al. (författare)
  • Towards determination of individual glandular dose
  • 2018
  • Ingår i: Medical Imaging 2018 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 9781510616356 ; 10573
  • Konferensbidrag (refereegranskat)abstract
    • Due to variations in amount and distribution of glandular breast tissue among women, the mean glandular dose (MGD) can be a poor measure of the individual glandular dose. Therefore, to improve the basis for risk assessment related to radiation dose from breast X-ray examinations, the distribution should be considered. Breast tomosynthesis (BT) is an imaging technique that may be used as an alternative or complement to standard mammography in breast cancer screening, and it could provide the required 3D-localisation of glandular tissue for estimation of the individual glandular dose. In this study, we investigated the possibility to localize glandular tissue from BT data and use a Monte Carlo simulation routine to estimate the glandular dose for software breast phantoms with different amount and distribution of glandular breast tissue. As an initial evaluation of the method, the local energy absorption in glandular tissue was estimated for seven breast phantoms and the corresponding phantoms recreated from reconstructed BT data. As expected, the normalized glandular dose was found to differ substantially with glandular distribution. This emphasizes the importance of glandular tissue localization for estimation of the individual glandular dose. The results showed good accuracy for estimation of normalized glandular dose using breast phantoms recreated from reconstructed BT image volumes (relative differences between -7.3% and +9.5%). Following this initial study, the method will be evaluated for more phantoms and potentially developed for patient cases. In the future it could become a useful tool in breast dosimetry as a step towards the individual glandular dose.
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19.
  • Lång, Kristina, et al. (författare)
  • Can horizontally oriented breast tomosynthesis image volumes or the use of a systematic search strategy improve interpretation? An eye tracking and free response human observer study
  • 2011
  • Ingår i: Proc. SPIE. - : SPIE. ; 7966:796606
  • Konferensbidrag (refereegranskat)abstract
    • Our aim was to evaluate if there is a benefit in diagnostic accuracy and efficiency of viewing breast tomosynthesis (BT) image volumes presented horizontally oriented, but also to evaluate the use of a systematic search strategy where the breast is divided, and analyzed consecutively, into two sections. These image presentations were compared to regular vertical image presentation. All methods were investigated using viewing procedures consisting of free scroll volume browsing, and a combination of initial cine loops at three different frame rates (9, 14, 25 fps) terminated upon request followed by free scroll volume browsing if needed. Fifty-five normal BT image volumes in MLO view were collected. In these, simulated lesions (20 masses and 20 clusters of microcalcifications) were randomly inserted, creating four unique image sets for each procedure. Four readers interpreted the cases in a random order. Their task was to locate the lesions, mark and assign a five level confidence scale. The diagnostic accuracy was analyzed using Jackknife Free Receiver Operating Characteristics (JAFROC). Time efficiency and visual search behavior were also investigated using eye tracking. Results indicate there was no statistically significant difference in JAFROC FOM between the different image presentations, although visual search was more time efficient when viewing horizontally oriented image volumes in medium cine loops.
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20.
  • Lång, Kristina, et al. (författare)
  • Optimizing viewing procedures of breast tomosynthesis image volumes using eye tracking combined with a free response human observer study
  • 2011
  • Ingår i: Medical Imaging 2011: Image Perception, Observer Performance, and Technology Assessment / SPIE Proceedings. - : SPIE. ; 7966:796602
  • Konferensbidrag (refereegranskat)abstract
    • The purpose of this study was to evaluate four different viewing procedures as part of improving viewing conditions of breast tomosynthesis (BT) image volumes. The procedures consisted of free scroll volume browsing, and a combination of initial cine loops at three different frame rates (9, 14 and 25 fps) terminated upon request followed by free scroll volume browsing. Fifty-five normal BT image volumes in MLO view were collected. In these, simulated lesions (20 masses and 20 clusters of microcalcifications) were randomly inserted, creating four unique image sets for each procedure. Four readers interpreted the cases in a random order. Their task was to locate a lesion, mark and assign a five level confidence scale. The diagnostic accuracy was analyzed using Jackknife Free Receiver Operating Characteristics (JAFROC). Time efficiency and visual search behavior were also investigated using eye tracking. The results indicate that there was no statistically significant difference in JAFROC FOM between the different viewing procedures, however the medium cine loop speed seemed to be the preferred viewing procedure in terms of total analyze time and dwell time.
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21.
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22.
  • Petersson, Hannie, et al. (författare)
  • Evaluation of the possibility to use thick slabs of reconstructed outer breast tomosynthesis slice images
  • 2016
  • Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 9781510600225 ; 9787
  • Konferensbidrag (refereegranskat)abstract
    • The large image volumes in breast tomosynthesis (BT) have led to large amounts of data and a heavy workload for breast radiologists. The number of slice images can be decreased by combining adjacent image planes (slabbing) but the decrease in depth resolution can considerably affect the detection of lesions. The aim of this work was to assess if thicker slabbing of the outer slice images (where lesions seldom are present) could be a viable alternative in order to reduce the number of slice images in BT image volumes. The suggested slabbing (an image volume with thick outer slabs and thin slices between) were evaluated in two steps. Firstly, a survey of the depth of 65 cancer lesions within the breast was performed to estimate how many lesions would be affected by outer slabs of different thicknesses. Secondly, a selection of 24 lesions was reconstructed with 2, 6 and 10 mm slab thickness to evaluate how the appearance of lesions located in the thicker slabs would be affected. The results show that few malignant breast lesions are located at a depth less than 10 mm from the surface (especially for breast thicknesses of 50 mm and above). Reconstruction of BT volumes with 6 mm slab thickness yields an image quality that is sufficient for lesion detection for a majority of the investigated cases. Together, this indicates that thicker slabbing of the outer slice images is a promising option in order to reduce the number of slice images in BT image volumes.
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23.
  • Petersson, Hannie, et al. (författare)
  • Monte Carlo simulation of breast tomosynthesis: visibility of microcalcifications at different acquisition schemes
  • 2015
  • Ingår i: Medical Imaging 2015: Physics of Medical Imaging. - : SPIE. - 0277-786X .- 1996-756X. ; 9412, s. 94121-94121
  • Konferensbidrag (refereegranskat)abstract
    • Microcalcifications are one feature of interest in mammography and breast tomosynthesis (BT). To achieve optimal conditions for detection of microcalcifications in BT imaging, different acquisition geometries should be evaluated. The purpose of this work was to investigate the influence of acquisition schemes with different angular ranges, projection distributions and dose distributions on the visibility of microcalcifications in reconstructed BT volumes. Microcalcifications were inserted randomly in a high resolution software phantom and a simulation procedure was used to model a MAMMOMAT Inspiration BT system. The simulation procedure was based on analytical ray tracing to produce primary images, Monte Carlo to simulate scatter contributions and flatfield image acquisitions to model system characteristics. Image volumes were reconstructed using the novel method super-resolution reconstruction with statistical artifact reduction (SRSAR). For comparison purposes, the volume of the standard acquisition scheme (50 degrees angular range and uniform projection and dose distribution) was also reconstructed using standard filtered backprojection (FBP). To compare the visibility and depth resolution of the microcalcifications, signal difference to noise ratio (SDNR) and artifact spread function width (ASFW) were calculated. The acquisition schemes with very high central dose yielded significantly lower SDNR than the schemes with more uniform dose distributions. The ASFW was found to decrease (meaning an increase in depth resolution) with wider angular range. In conclusion, none of the evaluated acquisition schemes were found to yield higher SDNR or depth resolution for the simulated microcalcifications than the standard acquisition scheme.
  •  
24.
  • Petersson, Hannie, et al. (författare)
  • VALIDATION OF A SIMULATION PROCEDURE FOR GENERATING BREAST TOMOSYNTHESIS PROJECTION IMAGES.
  • 2016
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420.
  • Tidskriftsartikel (refereegranskat)abstract
    • In order to achieve optimal diagnostic performance in breast tomosynthesis (BT) imaging, the parameters of the imaging chain should be evaluated. For the purpose of such evaluations, a simulation procedure based on the Monte Carlo code system Penelope and the geometry of a Siemens BT system has been developed to generate BT projection images. In this work, the simulation procedure is validated by comparing contrast and sharpness in simulated images with contrast and sharpness in real images acquired with the BT system. The results of the study showed a good agreement of sharpness in real and simulated reconstructed image planes, but the contrast was shown to be higher in the simulated compared with the real projection images. The developed simulation procedure could be used to generate BT images, but it is of interest to further investigate how the procedure could be modified to generate more realistic image noise and contrast.
  •  
25.
  •  
26.
  • Ruschin, Mark, et al. (författare)
  • Dose dependence of mass and microcalcification detection in digital mammography: free response human observer studies.
  • 2007
  • Ingår i: Medical physics. - : Wiley. - 0094-2405. ; 34:2, s. 400-7
  • Tidskriftsartikel (refereegranskat)abstract
    • 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 (JA-FROC) 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.
  •  
27.
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28.
  • Ruschin, Mark, et al. (författare)
  • Improved in-plane visibility of tumors using breast tomosynthesis
  • 2007
  • Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422 .- 1042-4687. ; 6510
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The purpose of this work was to evaluate and compare the visibility of simulated tumors in 2D digital mammography (DM) and breast tomosynthesis (BT) images of patients. Images of the same women were acquired on both a DM system (Mammomat Novation, Siemens) and a BT prototype system adapted from the same type of DM system. Using the geometrical properties of the two systems, simulated, ellipsoid-shaped tumors (average dimension: 8.4 mm × 6.6 mm × 5 mm) with irregular margins were projected and added to each DM image as well as each BT projection image prior to 3D reconstruction. The same beam quality and approximately the same total absorbed dose were used for each breast image acquisition on both systems. Two simulated tumors were added to each of thirty patient scans, yielding sixty cases. A series of 4-alternative forced choice (4-AFC) human observer experiments were conducted in order to determine what projected signal intensity (contrast) of the tumors in the DM images would be needed to achieve the same detectability as in the reconstructed BT images. Nine observers participated. For the BT 4-AFC experiment, when the signal intensity of the tumor on the central projection was 0.010 (natural logarithmic units) the mean percent of correct responses (PC) was measured to be 81.5%, which converted to a detectability index value (d') of 1.96. For the DM system, the same detectability was achieved at a signal intensity determined to be 0.038. Equivalent levels of tumor detection in BT images were thus achieved at around four times less projected signal intensity than in DM images, indicating that the use of BT may lead to earlier detection of breast cancer.
  •  
29.
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30.
  • Sartor, Hanna, et al. (författare)
  • Measuring mammographic density : comparing a fully automated volumetric assessment versus European radiologists' qualitative classification
  • 2016
  • Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 26:12, s. 4354-4360
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: Breast Imaging-Reporting and Data System (BI-RADS) mammographic density categories are associated with considerable interobserver variability. Automated methods of measuring volumetric breast density may reduce variability and be valuable in risk and mammographic screening stratification. Our objective was to assess agreement of mammographic density by a volumetric method with the radiologists' classification.METHODS: Eight thousand seven hundred and eighty-two examinations from the Malmö Breast Tomosynthesis Screening Trial were classified according to BI-RADS, 4th Edition. Volumetric breast density was assessed using automated software for 8433 examinations. Agreement between volumetric breast density and BI-RADS was descriptively analyzed. Agreement between radiologists and between categorical volumetric density and BI-RADS was calculated, rendering kappa values.RESULTS: The observed agreement between BI-RADS scores of different radiologists was 80.9 % [kappa 0.77 (0.76-0.79)]. A spread of volumetric breast density for each BI-RADS category was seen. The observed agreement between categorical volumetric density and BI-RADS scores was 57.1 % [kappa 0.55 (0.53-0.56)].CONCLUSIONS: There was moderate agreement between volumetric density and BI-RADS scores from European radiologists indicating that radiologists evaluate mammographic density differently than software. The automated method may be a robust and valuable tool; however, differences in interpretation between radiologists and software require further investigation.KEY POINTS: • Agreement between qualitative and software density measurements has not been frequently studied. • There was substantial agreement between different radiologists´ qualitative density assessments. • There was moderate agreement between software and radiologists' density assessments. • Differences in interpretation between software and radiologists require further investigation.
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31.
  • Svahn, Tony, et al. (författare)
  • In-plane artifacts in breast tomosynthesis quantified with a novel contrast-detail phantom
  • 2007
  • Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422 .- 1042-4687. ; 6510:PART 3, s. 1853-1864
  • Konferensbidrag (refereegranskat)abstract
    • The purpose of this work was to develop a contrast-detail phantom that can be used to evaluate image quality in breast tomosynthesis (BT) and as a first step use it to evaluate in-plane artifacts with respect to object size and contrast. The phantom was constructed using a Polylite [registered trademark] resin as bulk material, as it has x-ray mass attenuation properties similar to polymethyl methacrylate (PMMA), a common phantom material in mammography. Six different materials polyoxymethylene (POM), bakelite [registered trademark] , nylon, polycarbonate (PC), acrylonitrilebutadienestyrene (ABS) and polyethene (PE) - were selected to form the phantom details. For each of the six materials, five spherical objects were manufactured (diameters of 4, 8, 12, 16, and 20 mm) resulting in 30 objects that were embedded with their centres approximately aligned at the central plane of a 26 mm thick Polylite [registered trademark] block (210 mm × 300 mm). A 20 mm thick PMMA block was added to yield a phantom with attenuation properties similar to 45 mm PMMA that could simulate a so-called standard breast (50 mm thick, 50% glandular tissue). Images of the phantom were acquired using a BT prototype system that employs filtered backprojection for image reconstruction. The magnitude of the in-plane artifacts was evaluated and was found to increase linearly with increasing contrast (signal) level and size of the embedded objects. The contrast-detail phantom was found to be a useful tool for evaluating BT in-plane artifacts and might also be used to study out-of-plane artifacts and the effect of different acquisition and reconstruction parameters on image quality in BT.
  •  
32.
  • Timberg, Pontus (författare)
  • Breast Tomosynthesis: Aspects on detection and perception of simulated lesions
  • 2011
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The aim of this thesis was to investigate aspects on detectability of simulated lesions (microcalcifications and masses) in digital mammography (DM) and breast tomosynthesis (BT). Perception in BT image volumes were also investigated by evaluating certain reading conditions. The first study concerned the effect of system noise on the detection of masses and microcalcification clusters in DM images using a free-response task. System noise has an impact on image quality and is related to the dose level. It was found to have a substantial impact on the detection of microcalcification clusters, whereas masses were relatively unaffected. The effect of superimposed tissue in DM is the major limitation hampering the detection of masses. BT is a three-dimensional technique that reduces the effect of superimposed tissue. In the following two studies visibility was quantified for both imaging modalities in terms of the required contrast at a fixed detection performance (92% correct decisions). Contrast detail plots for lesions with sizes 0.2, 1, 3, 8 and 25 mm were generated. The first study involved only an in-plane BT slice, where the lesion centre appeared. The second study repeated the same procedure in BT image volumes for 3D distributed microcalcification clusters and 8 mm masses at two dose levels. Both studies showed that BT needs substantially less contrast than DM for lesions above 1 mm. Furthermore, the contrast threshold increased as the lesion size increased for both modalities. This is in accordance with the reduced effect of superimposed tissue in BT. For 0.2 mm lesions, substantially more contrast was needed. At equal dose, DM was better than BT for 0.2 mm lesions and microcalcification clusters. Doubling the dose substantially improved the detection in BT. Thus, system noise has a substantial impact on detection. The final study evaluated reading conditions for BT image volumes. Four viewing procedures were assessed: free scroll browsing only or combined with initial cine loops at frame rates of 9, 14 and 25 fps. They were viewed on a wide screen monitor placed in vertical or horizontal positions. A free-response task and eye tracking were utilized to record the detection performance, analysis time, visual attention and search strategies. Improved reading conditions were found for horizontally aligned BT image volumes when using free scroll browsing only or combined with a cine loop at the fastest frame rate.
  •  
33.
  • Timberg, Pontus, et al. (författare)
  • Detection of calcification clusters in digital breast tomosynthesis slices at different dose levels utilizing a SRSAR reconstruction and JAFROC
  • 2015
  • Ingår i: Medical Imaging 2015: Image Perception, Observer Performance, and Technology Assessment. - : SPIE. - 1996-756X .- 0277-786X. ; 9416, s. 941604-941604
  • Konferensbidrag (refereegranskat)abstract
    • 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 clusters 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). An FBP algorithm adapted to DBT (called standard FBP) and a SRSAR reconstruction method utilizing iterative reconstruction filtering, 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 clusters and assign confidence rating in randomly presented images from the whole image set (balanced by dose level). Each trial was separated by one week to reduce possible memory bias. The outcome was analyzed for statistical differences using Jackknife Alternative Free-response Receiver Operating Characteristics. Results: The results indicate that it is possible to 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.
  •  
34.
  • Timberg, Pontus, et al. (författare)
  • Impact of dose on observer performance in breast tomosynthesis using breast specimens
  • 2008
  • Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 6913, s. 9134-9134
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • The purpose of this study was to investigate the effect of dose on lesion detection† and characterization in breast tomosynthesis (BT), using human breast specimens. Images of 27 lesions in breast specimens were acquired on a BT prototype‡ based on a Mammomat Novation (Siemens) full-field digital mammography (FFDM) system. Two detector modes - binned (2×1 in the scan direction) and full resolution - and four BT exposure levels - approximately 2×, 1.5×, 1×, and 0.5× the total mAs at the same beam quality as used in a single FFDM view with a Mammomat Novation unit under automatic exposure control (AEC) conditions - were examined. The exposure for all BT scans was equally divided among 25 projections. An enhanced filtered back projection reconstruction method was applied with a constant filter setting. A human observer performance study was conducted in which the observers were forced to select the minimum (threshold) exposure level at which each lesion could be both detected and characterized for assessment of recall or not in a screening situation. The median threshold exposure level for all observers and all lesions corresponded to approximately 1×, which is half the exposure of what we currently use for BT. A substantial variation in exposure thresholds was noticed for different lesion types. For low contrast lesions with diffuse borders, an exposure threshold of approximately 2× was required, whereas for spiculated high contrast lesions and lesions with well defined borders, the exposure threshold was lower than 0.5×. The use of binned mode had no statistically significant impact on observer performance compared to full resolution mode. There was no substantial difference between the modes for the detection and characterization of the lesion types.
  •  
35.
  •  
36.
  • Timberg, Pontus, et al. (författare)
  • In-plane visibility of lesions using breast tomosynthesis
  • 2009
  • Ingår i: Third Malmö Conference on Medical Imaging: Optimisation in X-Ray and Molecular Imaging, Malmö, Sweden, 25-27 June 2009.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)
  •  
37.
  • Timberg, Pontus, et al. (författare)
  • In-plane visibility of lesions using breast tomosynthesis and digital mammography
  • 2010
  • Ingår i: Medical Physics. - : Wiley. - 0094-2405. ; 37:11, s. 5618-5626
  • Tidskriftsartikel (refereegranskat)abstract
    • 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 (BT2x). Threshold signal was defined as the lesion signal intensity required for a detectability index (d') 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 BT2x 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 BT2x 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. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3488899]
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38.
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39.
  • Timberg, Pontus, et al. (författare)
  • Investigation of viewing procedures for interpretation of breast tomosynthesis image volumes: a detection-task study with eye tracking.
  • 2013
  • Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 23:4, s. 997-1005
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: To evaluate the efficiency of different methods of reading breast tomosynthesis (BT) image volumes. METHODS: All viewing procedures consisted of free scroll volume browsing and three were combined with initial cine loops at three different frame rates (9, 14 and 25 fps). The presentation modes consisted of vertically and horizontally orientated BT image volumes. Fifty-five normal BT image volumes in mediolateral oblique view were collected. In these, simulated lesions were inserted, creating four unique image sets, one for each viewing procedure. Four observers interpreted the cases in a free-response task. Time efficiency, visual attention and search were investigated using eye tracking. RESULTS: Horizontally orientated BT image volumes were read faster than vertically when using free scroll browsing only and when combined with fast cine loop. Cine loops at slow frame rates were ruled out as inefficient. CONCLUSIONS: In general, horizontally oriented BT image volumes were read more efficiently. All viewing procedures except for slow frame rates were promising when assuming equivalent detection performance. KEY POINTS : • Breast tomosynthesis is increasingly used for breast cancer detection • There is a benefit in reading breast tomosynthesis image volumes presented horizontally • Align image content to visual field, especially for dynamic 3D images • Reading at slow frame rates was considered inefficient.
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40.
  •  
41.
  •  
42.
  • Timberg, Pontus, et al. (författare)
  • Optimization of image quality in breast tomosynthesis using lumpectomy and mastectomy specimens
  • 2007
  • Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1042-4687 .- 1605-7422. ; 6510:PART 2, s. 1379-1386
  • Konferensbidrag (refereegranskat)abstract
    • The purpose of this study was to determine how image quality in breast tomosynthesis (BT) is affected when acquisition modes are varied, using human breast specimens containing malignant tumors and/or microcalcifications. Images of thirty-one breast lumpectomy and mastectomy specimens were acquired on a BT prototype based on a Mammomat Novation (Siemens) full-field digital mammography system. BT image acquisitions of the same specimens were performed varying the number of projections, angular range, and detector signal collection mode (binned and non-binned in the scan direction). An enhanced filtered back projection reconstruction method was applied with constant settings of spectral and slice thickness filters. The quality of these images was evaluated via relative visual grading analysis (VGA) human observer performance experiments using image quality criteria. Results from the relative VGA study indicate that image quality increases with number of projections and angular range. A binned detector collecting mode results in less noise, but reduced resolution of structures. Human breast specimens seem to be suitable for comparing image sets in BT with image quality criteria.
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43.
  • Timberg, Pontus, et al. (författare)
  • Potential for lower absorbed dose in digital mammography: A JAFROC experiment using clinical hybrid images with simulated dose reduction
  • 2006
  • Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 6146, s. 14614-14614
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • To determine how image quality linked to tumor detection is affected by reducing the absorbed dose to 50% and 30% of the clinical levels represented by an average glandular dose (AGO) level of 1.3 mGy for a standard breast according to European guidelines. Materials and methods: 90 normal, unprocessed images were acquired from the screening department using a full-field digital mammography (FFDM) unit Mammomat Novation (Siemens). Into 40 of these, one to three simulated tumors were inserted per image at various positions. These tumors represented irregular-shaped malignant masses. Dose reduction was simulated in all 90 images by adding simulated quantum noise to represent images acquired at 50% and 30% of the original dose, resulting in 270 images, which were subsequently processed for final display. Four radiologists participated in a free-response receiver operating characteristics (FROG) study in which they searched for and marked suspicious positions of the masses as well as rated their degree of suspicion of occurrence on a one to four scale. Using the jackknife FROG (JAFROC) method, a score between 0 and 1 (where 1 represents best performance), referred to as a figure-of-merit (FOM), was calculated for each dose level. Results: The FOM was 0.73, 0.70, and 0.68 for the 100%, 50% and 30% dose levels, respectively. Using Analysis of the Variance (ANOVA) to test for statistically significant differences between any two of the three FOMs revealed that they were not statistically distinguishable (p-value of 0.26). Conclusion: For the masses used in this experiment, there was no significant change in detection by increasing quantum noise, thus indicating a potential for dose reduction.
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44.
  •  
45.
  • Timberg, Pontus, et al. (författare)
  • Visibility of microcalcification clusters and masses in breast tomosynthesis image volumes and digital mammography: A 4AFC human observer study
  • 2012
  • Ingår i: Medical Physics. - : Wiley. - 0094-2405. ; 39:5, s. 2431-2437
  • Tidskriftsartikel (refereegranskat)abstract
    • 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 (BT25) was approximately twice that of a single DM view. By excluding every other projection image from the reconstruction (BT13), 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-t) to achieve a detectability index (d') of 2.5 (i.e., 92.5% correct decisions) was determined. Results: The St 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. St for microcalcification detection was higher for BT than for DM at both BT dose levels (BT25 and BT13), with a statistically significant difference in St between DM and BT13. These results indicate a dose-dependent decrease in detection performance in BT for detection of microcalcifications. Conclusions: In agreement with previous investigations, masses of size 8 mm can be detected with less contrast in BT than in DM indicating improved detection performance for BT. However, for the investigated microcalcifications, the results of this study indicate potentially worse performance for BT than for DM at the same dose level. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.3694105]
  •  
46.
  • Timberg, Pontus, et al. (författare)
  • Visibility of single spiculations in digital breast tomosynthesis
  • 2013
  • Ingår i: Medical Imaging 2013: Image Perception, Observer Performance, And Technology Assessment. - : SPIE. - 0277-786X .- 1996-756X. ; 8673, s. 86731-86731
  • Konferensbidrag (refereegranskat)abstract
    • 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: +/- pi/4 or +/- 3 pi/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 x 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.
  •  
47.
  • Tingberg, Anders, et al. (författare)
  • BIRADS classification in breast tomosynthesis compared to mammography and ultrasonography
  • 2008
  • Ingår i: Digital Mammography, Proceedings. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783540705376 ; 5116, s. 67-73
  • Konferensbidrag (refereegranskat)abstract
    • This paper presents the Malmo Breast tomosynthesis project The tomosynthesis equipment is described as well as the patient selection and image acquisition. Special fucus is given to one of the studies of the project, which is a comparison of the diagnostic performance between breast tomosynthesis (BT), digital mammography (DM) and ultrasonography (US): tumor classification according to the BIRADS system was performed on 40 cancers imaged with DM, US and BT. The patients were selected on the basis of subtle signs of breast cancer on DM or negative findings on the basis of subtle signs of breast cancer on DM or negative findings on DM but suspicious lesions on US. The BIRADS scores based on the BT images were significantly higher than 1-view DM and 2-view DM, and equal 2-view DM, and equal to 2-view plus US. The results suggest that BT may be a suitable technique for breast cancer screening.
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48.
  • Tingberg, Anders, et al. (författare)
  • Breast Cancer Screening With Tomosynthesis-Initial Experiences
  • 2011
  • Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 147:1-2, s. 180-183
  • Tidskriftsartikel (refereegranskat)abstract
    • Experiences gained so far using tomosynthesis for breast cancer screening will be reported. A short summary of results from preparatory studies will also be presented. The sensitivity and specificity of breast tomosynthesis (BT) will be compared with conventional two-dimensional digital mammography (DM) for breast cancer screening in a population-based study. Over 2000 women have been examined so far with BT and DM. The BT reading is significantly more time-consuming than the DM reading. Preparatory studies have shown that BT has a higher diagnostic precision and higher accuracy of size measurements and stage determination than DM. There is potential to use lower compression force with BT compared with DM, without decreasing the diagnostic accuracy. BT might play an important role in clinical as well as screening mammography. A large-scale population-based study to investigate BT as a screening modality is underway.
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49.
  • Tingberg, Anders, et al. (författare)
  • Preface
  • 2016
  • Ingår i: Breast Imaging : 13th International Workshop, IWDM 2016 Malmö, Sweden, June 19 – 22, 2016 - 13th International Workshop, IWDM 2016 Malmö, Sweden, June 19 – 22, 2016. - Cham : Springer International Publishing. - 0302-9743. - 9783319415451 - 9783319415468 ; 9699
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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50.
  • Tomic, Hanna, et al. (författare)
  • Simulation of breast lesions based upon fractal Perlin noise
  • 2023
  • Ingår i: Physica Medica. - 1120-1797. ; 114
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: Steadily increasing use of computational/virtual phantoms in medical physics has motivated expanding development of new simulation methods and data representations for modelling human anatomy. This has emphasized the need for increased realism, user control, and availability. In breast cancer research, virtual phantoms have gained an important role in evaluating and optimizing imaging systems. For this paper, we have developed an algorithm to model breast abnormalities based on fractal Perlin noise. We demonstrate and characterize the extension of this approach to simulate breast lesions of various sizes, shapes, and complexity. Materials and method: Recently, we developed an algorithm for simulating the 3D arrangement of breast anatomy based on Perlin noise. In this paper, we have expanded the method to also model soft tissue breast lesions. We simulated lesions within the size range of clinically representative breast lesions (masses, 5–20 mm in size). Simulated lesions were blended into simulated breast tissue backgrounds and visualized as virtual digital mammography images. The lesions were evaluated by observers following the BI-RADS assessment criteria. Results: Observers categorized the lesions as round, oval or irregular, with circumscribed, microlobulated, indistinct or obscured margins. The majority of the simulated lesions were considered by the observers to have a realism score of moderate to well. The simulation method provides almost real-time lesion generation (average time and standard deviation: 1.4 ± 1.0 s). Conclusion: We presented a novel algorithm for computer simulation of breast lesions using Perlin noise. The algorithm enables efficient simulation of lesions, with different sizes and appearances.
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