| 1. |
- Dustler, Magnus, et al.
(författare)
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The characteristics of malignant breast tumors imaged using a prototype mechanical imaging system as an adjunct to mammography
- 2016
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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
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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. |
- Tingberg, Anders, et al.
(författare)
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Preface
- 2016
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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
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Andersson, Ingvar, et al.
(författare)
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Breast tomosynthesis and digital mammography: a comparison of breast cancer visibility and BIRADS classification in a population of cancers with subtle mammographic findings.
- 2008
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 18, s. 2817-2825
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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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| 5. |
- Andersson, Karin, 1989-
(författare)
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Metal artifacts in computed tomography : impact of reduction methods on image quality and radiotherapy treatment planning
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Degradation of image quality by metal artifacts is a common problem in computed tomography (CT) imaging, which can limit the diagnostic value of a CT examination and also introduce inaccuracies in radiotherapy (RT) treatment planning. In recent years, commercial metal artifact reduction (MAR) methods have been launched by several CT vendors. The overall aim of this thesis was to evaluate MAR methods in diagnostic imaging and RT treatment planning.Evaluations of hip prosthesis phantom CT images showed that MAR algorithms in general improved image quality, based on both visual grading analysis and quantitative measures, while the application of virtual monoenergetic reconstructions insufficiently reduced metal artifacts. In some cases additional artifacts were introduced by the MAR algorithms. MAR algorithms were also evaluated in hip prosthesis phantom CT imaging used for proton therapy treatment planning, where improvements in dose calculation accuracy were observed.Studies of Head & Neck (H&N) implant CT images in RT treatment planning were also performed. By visual grading of anatomy visualization with respect to target delineation in dental implant patient images, MAR algorithms were shown to significantly improve image quality. However, only minor effects of H&N implant artifacts on proton dose distributions were seen. The impact might be greater for more severe artifacts than those studied here, and thus further investigations of such cases are needed.In conclusion, MAR algorithms have been shown to enhance image quality for diagnostic applications and to improve anatomy visualization in RT treatment planning. The MAR algorithms led to increased proton dose calculation accuracy in some cases, while in other situations only minor changes were seen.
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| 6. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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A PHANTOM STUDY SHOWING THE IMPORTANCE OF COMPRESSION IN CONVENTIONAL DIAGNOSTIC X-RAY EXAMINATIONS.
- 2010
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; Apr 7, s. 78-80
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Tidskriftsartikel (refereegranskat)abstract
- Compression was earlier an important and well-managed part of the clinical routine, but during the past 15-20 y the use has diminished, except for mammography, where it is a prerequisite for having images of high quality and low radiation dose. According to national and European regulations and recommendations, it is important to apply the compression technique to obtain the optimal image quality and radiation dose in common conventional diagnostic examinations. Current experience of compression technique is, however, based on studies carried out a long time ago and with analogue imaging techniques. An anthropomorphic phantom was used to show the importance of compression in conventional X-ray examinations. The patient thicknesses on volunteers with and without compression was measured. This measurement was done to investigate compression potential on patients and to select suitable phantom thicknesses. The X-ray examinations that were included in the study were abdomen overview, lumbar spine and the pelvis. The results from the phantom study showed a large dependency of the kerma-area product value on the phantom thickness. The phantom study suggests that there is a potential for significant reduction of radiation dose to the patient by using compression also with modern X-ray techniques. A dose reduction of up to 50 % or even more may be obtained.
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| 7. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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Evaluation of an iterative model-based reconstruction of pediatric abdominal CT with regard to image quality and radiation dose
- 2018
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 59:6, s. 740-747
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIn pediatric patients, computed tomography (CT) is important in the medical chain of diagnosing and monitoring various diseases. Because children are more radiosensitive than adults, they require minimal radiation exposure. One way to achieve this goal is to implement new technical solutions, like iterative reconstruction.PurposeTo evaluate the potential of a new, iterative, model-based method for reconstructing (IMR) pediatric abdominal CT at a low radiation dose and determine whether it maintains or improves image quality, compared to the current reconstruction method.Material and MethodsForty pediatric patients underwent abdominal CT. Twenty patients were examined with the standard dose settings and 20 patients were examined with a 32% lower radiation dose. Images from the standard examination were reconstructed with a hybrid iterative reconstruction method (iDose4), and images from the low-dose examinations were reconstructed with both iDose4 and IMR. Image quality was evaluated subjectively by three observers, according to modified EU image quality criteria, and evaluated objectively based on the noise observed in liver images.ResultsVisual grading characteristics analyses showed no difference in image quality between the standard dose examination reconstructed with iDose4 and the low dose examination reconstructed with IMR. IMR showed lower image noise in the liver compared to iDose4 images. Inter- and intra-observer variance was low: the intraclass coefficient was 0.66 (95% confidence interval = 0.60–0.71) for the three observers.ConclusionIMR provided image quality equivalent or superior to the standard iDose4 method for evaluating pediatric abdominal CT, even with a 32% dose reduction.
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| 8. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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Improvements to image quality using hybrid and model-based iterative reconstructions: a phantom study.
- 2017
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 58:1, s. 53-61
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Tidskriftsartikel (refereegranskat)abstract
- The number of computed tomography (CT) examinations is increasing and leading to an increase in total patient exposure. It is therefore important to optimize CT scan imaging conditions in order to reduce the radiation dose. The introduction of iterative reconstruction methods has enabled an improvement in image quality and a reduction in radiation dose.
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| 9. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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MODEL-BASED ITERATIVE RECONSTRUCTION ENABLES THE EVALUATION OF THIN-SLICE COMPUTED TOMOGRAPHY IMAGES WITHOUT DEGRADING IMAGE QUALITY OR INCREASING RADIATION DOSE.
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 100-106
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Tidskriftsartikel (refereegranskat)abstract
- Computed tomography (CT) is one of the most important modalities in a radiological department. This technique not only produces images that enable radiological reports with high diagnostic confidence, but it may also provide an elevated radiation dose to the patient. The radiation dose can be reduced by using advanced image reconstruction algorithms. This study was performed on a Brilliance iCT, equipped with iDose(4) iterative reconstruction and an iterative model-based reconstruction (IMR) method. The purpose was to investigate the effect of reduced slice thickness combined with an IMR method on image quality compared with standard slice thickness with iDose(4) reconstruction. The results of objective and subjective image quality evaluations showed that a thinner slice combined with IMR can improve the image quality and reduce partial volume artefacts compared with the standard slice thickness with iDose(4). In conclusion, IMR enables reduction of the slice thickness while maintaining or even improving image quality versus iDose(4).
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| 10. |
- Aurumskjöld, Marie-Louise, et al.
(författare)
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Model based iterative reconstruction IMR gives possibility to evaluate thinner slice thicknesses than conventional iterative reconstruction iDose(4) - a phantom study
- 2015
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Ingår i: Medical Imaging 2015: Physics of Medical Imaging. - : SPIE. - 1996-756X .- 0277-786X. ; 9412, s. 94124-94124
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Konferensbidrag (refereegranskat)abstract
- Computed tomography (CT) is one of the most important modalities in a radiological department, which produces images with high diagnostic confidence, but in some cases contributes to a high radiation dose to the patient. The radiation dose can be reduced by the use of advanced image reconstruction algorithms. This study was done on a Philips Brilliance iCT with iterative reconstruction iDose(4) and model-based iterative reconstruction IMR. The purpose was to investigate the effect on the image quality with thin slice images reconstructed with IMR, compared to standard slice thickness reconstructed with iDose(4). Objective measurements of noise and contrast-to-noise ratio were performed using an image quality phantom, an anthropomorphic phantom and clinical cases. Subjective evaluations of low-contrast resolution were performed by observers using an image quality phantom. IMR gives strong noise reduction and enhanced low-contrast and thereby enable selection of thinner slice thickness. Objective evaluation of image noise shows that thin slices reconstructed with IMR provides lower noise than thicker slice images reconstructed with iDose(4). With IMR the slice thickness is of less importance for the noise. With thinner slices the partial volume artefacts becomes less pronounced. In conclusion, we have shown that IMR enables reduction of the slice thickness and at the same time maintain or even reduce the noise level compared to iDose(4) reconstruction with standard slice thickness. This will subsequently result in an improvement of image quality for images reconstructed with IMR.
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