| 51. |
- Håkansson, Markus, et al.
(författare)
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ViewDEX - A Java-based software for presentation and evaluation of medical images in observer performance studies
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 6509
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Observer performance studies are time-consuming tasks, both for the participating observers and for the scientists collecting and analyzing the data. A possible way to optimize such studies is to perform the study in a completely digital environment. A software tool - ViewDEX (Viewer for Digital Evaluation of X-ray images) - has been developed in Java, enabling it to function on almost any computer. ViewDEX is a DICOM-compatible software tool that can be used to display medical images with simultaneous registration of the observer's response. ViewDEX is designed so that the user in a simple way can alter the types of questions and images presented to the observers, enabling ROC, MAFC and visual grading studies to be conducted in a fast and efficient way. The software can also be used for bench marking and for educational purposes. The results from each observer are saved in a log file, which can be exported for further analysis. The software is freely available for non-commercial purposes.
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| 52. |
- Håkansson, Markus, et al.
(författare)
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ViewDEX: an efficient and easy-to-use software for observer performance studies
- 2010
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 42-51
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Tidskriftsartikel (refereegranskat)abstract
- The development of investigation techniques, image processing, workstation monitors, analysing tools etc. within the field of radiology is vast, and the need for efficient tools in the evaluation and optimisation process of image and investigation quality is important. ViewDEX (Viewer for Digital Evaluation of X-ray images) is an image viewer and task manager suitable for research and optimisation tasks in medical imaging. ViewDEX is DICOM compatible and the features of the interface (tasks, image handling and functionality) are general and flexible. The configuration of a study and output (for example, answers given) can be edited in any text editor. ViewDEX is developed in Java and can run from any disc area connected to a computer. It is free to use for non-commercial purposes and can be downloaded from http://www.vgregion.se/sas/viewdex. In the present work, an evaluation of the efficiency of ViewDEX for receiver operating characteristic (ROC) studies, free-response ROC (FROC) studies and visual grading (VG) studies was conducted. For VG studies, the total scoring rate was dependent on the number of criteria per case. A scoring rate of approximately 150 cases h(-1) can be expected for a typical VG study using single images and five anatomical criteria. For ROC and FROC studies using clinical images, the scoring rate was approximately 100 cases h(-1) using single images and approximately 25 cases h(-1) using image stacks ( approximately 50 images case(-1)). In conclusion, ViewDEX is an efficient and easy-to-use software for observer performance studies.
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| 53. |
- Ivarsson, Jonas, 1976, et al.
(författare)
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Aligning Video-And Structured Data for Imaging Optimisation.
- 2021
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 195:3-4
-
Tidskriftsartikel (refereegranskat)abstract
- Imaging optimisation can benefit from combining structured data with qualitative data in the form of audio and video recordings. Since video is complex to work with, there is a need to find a workable solution that minimises the additional time investment. The purpose of the paper is to outline a general workflow that can begin to address this issue. What is described is a data management process comprising the three steps of collection, mining and contextualisation. This process offers a way to work systematically and at a large scale without succumbing to the context loss of statistical methods. The proposed workflow effectively combines the video and structured data to enable a new level of insights in the optimisation process.
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| 54. |
- Ivarsson, Jonas, 1976, et al.
(författare)
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The application of improved, structured and interactive group learning methods in diagnostic radiology
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 169:1-4, s. 416-421
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Tidskriftsartikel (refereegranskat)abstract
- This study provides an example on how it is possible to design environments in a diagnostic radiology department that could meet learning demands implied by the introduction of new imaging technologies. The innovative aspect of the design does not result from the implementation of any specific tool for learning. Instead, advancement is achieved by a novel set-up of existing technologies and an interactive format that allows for focussed discussions between learners with different levels of expertise. Consequently, the study points to what is seen as the underexplored possibilities of tailoring basic and specialist training that meet the new demands given by leading-edge technologies.
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| 55. |
- Jadidi, M., et al.
(författare)
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Dependency of image quality on acquisition protocol and image processing in chest tomosynthesis-a visual grading study based on clinical data
- 2018
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Ingår i: British Journal of Radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 91:1087
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To compare the quality of images obtained with two different protocols with different acquisition time and the influence from image post processing in a chest digital tomosynthesis (DTS) system. Methods: 20 patients with suspected lung cancer were imaged with a chest X-ray equipment with tomosynthesis option. Two examination protocols with different acquisition times (6.3 and 12 s) were performed on each patient. Both protocols were presented with two different image post-processing (standard DTS processing and more advanced processing optimised for chest radiography). Thus, 4 series from each patient, altogether 80 series, were presented anonymously and in a random order. Five observers rated the quality of the reconstructed section images according to predefined quality criteria in three different classes. Visual grading characteristics (VGC) was used to analyse the data and the area under the VGC curve (AUC(VGC)) was used as figure-of-merit. The 12 s protocol and the standard DTS processing were used as references in the analyses. Results: The protocol with 6.3s acquisition time had a statistically significant advantage over the vendor-recommended protocol with 12s acquisition time for the classes of criteria, Demarcation (AUC(VGC)= 0.56, p = 0.009) and Disturbance (AUC(VGC) = 0.58, p < 0.001). A similar value of AUC(VGC) was found also for the class Structure (definition of bone structures in the spine) (0.56) but it could not be statistically separated from 0.5 (p = 0.21). For the image processing, the VGC analysis showed a small but statistically significant advantage for the standard DTS processing over the more advanced processing for the classes of criteria Demarcation (AUC vGc = 0.45, p = 0.017) and Disturbance (AUC(VGC) = 0.43, p = 0.005). A similar value of AUC(VGC)was found also for the class Structure (0.46), but it could not be statistically separated from 0.5 (p = 0.31). Conclusion: The study indicates that the protocol with 6.3 s acquisition time yields slightly better image quality than the vender-recommended protocol with acquisition time 12 s for several anatomical structures. Furthermore, the standard gradation processing (the vendor- recommended post-processing for DTS), yields to some extent advantage over the gradation processing/multiobjective frequency processing/flexible noise control processing in terms of image quality for all classes of criteria. Advances In knowledge: The study proves that the image quality may be strongly affected by the selection of DTS protocol and that the vendor-recommended protocol may not always be the optimal choice.
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| 56. |
- Jadidi, M, et al.
(författare)
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Evaluation of a new system for chest tomosynthesis : aspects of image quality of different protocols determined using an anthropomorphic phantom.
- 2015
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Ingår i: British Journal of Radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 88:1053, s. 20150057-
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare the image quality obtained with the different protocols in a new chest digital tomosynthesis (DTS) system.METHODS: A chest phantom was imaged with chest X-ray equipment with DTS. 10 protocols were used, and for each protocol, nine acquisitions were performed. Four observers visually rated the quality of the reconstructed section images according to pre-defined quality criteria in four different classes. The data were analysed with visual grading characteristics (VGC) analysis, using the vendor-recommended protocol [12-s acquisition time, source-to-image distance (SID) 180 cm] as reference, and the area under the VGC curve (AUCVGC) was determined for each protocol and class of criteria.RESULTS: Protocols with a smaller swing angle resulted in a lower image quality for the classes of criteria "disturbance" and "homogeneity in nodule" but a higher image quality for the class "structure". The class "demarcation" showed little dependency on the swing angle. All protocols but one (6.3 s, SID 130 cm) obtained an AUCVGC significantly <0.5 (indicating lower quality than reference) for at least one class of criteria.CONCLUSION: The study indicates that the DTS protocol with 6.3 s yields image quality similar to that obtained with the vendor-recommended protocol (12 s) but with the clinically important advantage for patients with respiratory impairment of a shorter acquisition time.ADVANCES IN KNOWLEDGE: The study demonstrates that the image quality may be strongly affected by the choice of protocol and that the vendor-recommended protocol may not be optimal.
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| 57. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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A phantom study of nodule size evaluation with chest tomosynthesis and computed tomography.
- 2010
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 140-143
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to investigate nodule size measurements with chest tomosynthesis (TS) and computed tomography (CT). A 26-mm thick phantom, composed of a Polylite block with embedded spheres of different materials and sizes (4-20 mm), was scanned by both CT and TS. Six observers without prior knowledge of the true diameters of the spheres independently measured the diameter of the spheres on the CT and TS images. Four observers were allowed to change the window settings and two of the observers used predetermined fixed viewing conditions. The mean relative errors for all observers and all measured spheres compared with the known diameter of the spheres were 1.4 % (standard deviation, SD: 5.4 %) on CT images and -1.1 % (SD: 5.0 %) on TS images. With regard to the four observers where the window settings were at the discretion of the observer, the mean relative errors were 1.4 % (SD: 6.4 %) on CT images and -1.7 % (SD: 5.7 %) on TS images. Regarding the two observers using identical viewing conditions the mean relative error was 1.5 % (SD: 2.8 %) on CT images and 0.2 % (SD: 2.6 %) on TS images. In conclusion, the study suggests that nodule size measurements on chest TS might be an alternative to measurements on CT.
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| 58. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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A Retrospective Study of Chest Tomosynthesis as a Tool for Optimizing the use of Computed Tomography Resources and Reducing Patient Radiation Exposure
- 2014
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Ingår i: Academic Radiology. - : Elsevier BV. - 1076-6332. ; 21:11, s. 1427-1433
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: To investigate potential benefits and drawbacks of the clinical use of chest tomosynthesis (CTS), to what extent CTS obviates the need for chest computed tomography (CT), and what reduction in radiation dose thereby can be achieved. Materials and Methods: The Regional Ethical Review Board approved the follow-up study of patients examined with CTS as part of clinical routine. For each case, two radiologists in consensus determined whether CT would have been performed, had CTS not been an option, and whether CTS was an adequate examination. Thereafter, it was determined whether the use of CTS instead of CT in retrospect was beneficial, neutral, or detrimental for the radiological work-up. The radiation dose to the patient population was determined both for the actual clinical situation and for the alternative scenario that would result, had CTS not been available. Results: During 1 month 3.5 years before the survey, 149 patients (74 women, age 18-91 years) had undergone CTS for clinical purposes. It was judged that CT would have been performed in 100 cases, had CTS not been available, and that CTS obviated the need for CT in 80 cases. CTS was judged as beneficial, neutral, and detrimental for the radiological work-up in 85, 13, and two cases, respectively. For the entire study population, the use of CTS decreased the average effective dose from 2.7 to 0.7 mSv. Conclusions: The present study indicates that CTS may have benefits for the radiological work-up as it has the potential to both optimize the use of CT resources and reduce the effective dose to the patient population. A drawback is that CTS examinations may fail to reveal pathology visible with CT and in clinically doubtful cases further investigations including other imaging procedures should be considered.
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| 59. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Chest tomosynthesis: technical and clinical perspectives.
- 2014
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Ingår i: Seminars in respiratory and critical care medicine. - : Georg Thieme Verlag KG. - 1098-9048 .- 1069-3424. ; 35:1, s. 17-26
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Tidskriftsartikel (refereegranskat)abstract
- The recent implementation of chest tomosynthesis is built on the availability of large, dose-efficient, high-resolution flat panel detectors, which enable the acquisition of the necessary number of projection radiographs to allow reconstruction of section images of the chest within one breath hold. A chest tomosynthesis examination obtains the increased diagnostic information provided by volumetric imaging at a radiation dose comparable to that of conventional chest radiography. There is evidence that the sensitivity of chest tomosynthesis may be at least three times higher than for conventional chest radiography for detection of pulmonary nodules. The sensitivity increases with increasing nodule size and attenuation and decreases for nodules with subpleural location. Differentiation between pleural and subpleural lesions is a known pitfall due to the limited depth resolution in chest tomosynthesis. Studies on different types of pathology report increased detectability in favor of chest tomosynthesis in comparison to chest radiography. The technique provides improved diagnostic accuracy and confidence in the diagnosis of suspected pulmonary lesions on chest radiography and facilitates the exclusion of pulmonary lesions in a majority of patients, avoiding the need for computed tomography (CT). However, motion artifacts can be a cumbersome limitation and breathing during the tomosynthesis image acquisition may result in severe artifacts significantly affecting the detectability of pathology. In summary, chest tomosynthesis has been shown to be superior to chest conventional radiography for many tasks and to be able to replace CT in selected cases. In our experience chest tomosynthesis is an efficient problem solver in daily clinical work.
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| 60. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Extracolonic Findings-Identification at Low-Dose CTC.
- 2021
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 195:3-4
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Tidskriftsartikel (refereegranskat)abstract
- In contrast to optical colonoscopy, computed tomography colonography (CTC) has the ability to reveal pathology outside of the colon. While identification of colorectal lesions at CTC requires only limited radiation dose, the detection of abnormalities in extracolonic soft tissue requires more radiation. The purpose of this study was to investigate the influence of ultra-low-dose (ULD) CTC on the detection and characterisation of extracolonic findings. In a prospective study 49 patients with colorectal symptoms were examined with CTC adding a ULD series (mean effective dose 0.9 ± 0.4 mSv) to the normal unenhanced standard dose (SD) series (mean effective dose 3.6 ± 1.2 mSv). Five radiologists individually and blindly evaluated the ULD, followed by evaluation of the SD after ≥9 weeks (median 35 weeks). A ViewDEX-based examination protocol was used, including a confidence scale and a graded assessment of need for follow-up according to the CTC Reporting and Data System (C-RADS E0-E4). The reference findings comprised the combined information from CTC (ULD, SD and contrast-enhanced CTC series) and a 4-year radiological and clinical follow-up. For the overall detection of reference findings (E2-E4) we found a statistically significant difference in favour of SD. This, however, was not the case when looking at classification of possibly important/important reference findings (E3-E4). Our results suggest that CTC with ULD (0.9 mSv) is comparable to SD (3.6 mSv) for identification of clinically relevant extracolonic pathology, but there is a large inter-observer variability.
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