| 1. |
- Almén, Anja, 1964, et al.
(författare)
-
The process of optimisation of radiological protection – the significance of diagnostic reference levels
- 2015
-
Ingår i: Optimisation in X-ray and Molecular Imaging 2015 - the Fourth Malmö Conference on Medical Imaging, Gothenburg, Sweden, 28-30 May 2015.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The system of diagnostic reference levels in medicine has been presented as a tool to advice on when a local review of the procedures and equipment is warranted in order to determine whether the protection has been adequately optimised. The system is somewhat country specific, presumably due to different national regulations or guidelines, but as a whole relies on the same principles and standards. Diagnostic reference levels are typically set for standardised patients and procedures with minor considerations of the need to manage individual patient characteristics or specific medical tasks in the optimisation process. Optimisation of radiological protection should involve key aspects influencing the radiation dose to the patients and also include the needs of optimising the protection for each patient individually. The actual given radiation dose to the patient is affected by a number of factors, amongst other things equipment specific features and training of staff performing the examinations. This emphases the need to take a holistic approach and integrate different clinical processes - e.g. purchasing of equipment or the implementation of new examination protocols in the clinic – in the process of optimisation. Taking this approach gives the opportunity to evaluate the significance of the current system of diagnostic reference levels in the process of optimisation and to identify other reference levels supporting the process of optimisation. This paper will investigate the optimisation process and identify key instances where reference levels could provide support to the optimisation process. The issue of optimising the individual examination with regard to patient characteristics and medical indication will be specifically addressed.
|
|
| 2. |
- Arvidsson, Jonathan, et al.
(författare)
-
Image fusion of two FBP-reconstructed digital tomosynthesis volumes from frontal and lateral acquisitions
- 2015
-
Ingår i: Optimisation in X-ray and Molecular Imaging 2015 - the Fourth Malmö Conference on Medical Imaging, Gothenburg, Sweden, 28-30 May 2015.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: Digital tomosynthesis (DTS) has been used in chest imaging as a low radiation dose alternative to computed tomography (CT). DTS can to a certain degree separate overlapping anatomical structures at different depth levels using traditional filtered back projection (FBP) reconstruction schemes. However, the spatial resolution remains limited in the out-of-plane dimension. The aim of this work was to investigate if utilizing information from both a frontal and lateral DTS acquisition will give a more accurate 3D representation of the examined object. Method: As a first indication of whether a dual-view DTS data acquisition can yield a fair resolution in the three spatial dimensions, a manual registration between two reconstructed DTS volumes, one being a frontal data acquisition and the other a lateral one, was performed. An anthropomorphic chest phantom was scanned using a linear DTS acquisition in frontal and lateral directions, at 120 kVp. The two corresponding volumes where reconstructed, downsampled to a lower resolution and manually co-registered. Being manual, the registration step was subjective and thus included identifying suitable landmarks that could be used to ensure that the correct rigid transformation between the two volumes was found. Finally a CT examination of the phantom, used as a ground truth 3D representation, was manually co-registered to the DTS data. The reconstruction, downsampling and co-registering was performed using both commercial and freely available software. Major Findings: The resulting co-registered volume gave a more accurate isotropic 3D representation of the examined object than the two original reconstructions. Oblique planes were more accurately reproduced by the co-registered volume whereas coronal and sagittal planes were better reproduced by the original frontally and laterally reconstructed volumes. Conclusions: The proposed method shows that fusing frontally and laterally reconstructed DTS volumes is possible and yields a more accurate isotropic 3D representation of the examined object than original DTS reconstructions. By utilizing a dual-view DTS acquisition geometry some advantages of including DTS data from orthogonal projection angles were illustrated. The findings are encouraging for further work on reconstruction algorithms using a dual-view DTS acquisition geometry.
|
|
| 3. |
|
|
| 4. |
- Ásgeirsdóttir, Helga, et al.
(författare)
-
Depiction of anatomic structures of relevance for scoring of cystic fibrosis changes by chest tomosynthesis and computed tomography
- 2014
-
Ingår i: Journal of Cystic Fibrosis. 37th European Cystic Fibrosis Conference, 11-14 June 2014, Gothenburg, Sweden. ; 13:Suppl. 2
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Chest radiography (CR) and computed tomography (CT) are commonly used for imaging of patients with cystic fibrosis, and scoring is applied to assess disease severity. Chest tomosynthesis (CTS) is a new imaging modality providing better anatomic visualization than CR at radiation doses and costs lower than CT. Objective: To compare visibility and size of anatomic structures of relevance for scoring in CTS and CT images. Methods: 21 adult patients with cystic fibrosis were examined both with CTS (VolumeRAD; GE Healthcare) and volumetric CT (LightSpeed Pro 16, LightSpeed VCT, Discovery CT750HD; GE healthcare and Somatom Definition, Siemens Medical Solutions). The average effective dose for a standard patient was 0.13 and 4.5 mSv for CTS and CT, respectively. Comparison of visibility and manual measurements of diameters of the central and peripheral bronchi and their accompanying artery, as well as bronchial wall thickness (BWT), were performed in a non-blinded fashion. Results: All central structures could be evaluated. Mean difference in diameter of central bronchi, accompanying artery and BWT between CTS and CT was −0.6 (SD 0.6), −0.7 (SD 0.7) and −0.4 (SD 0.2) mm, respectively. Peripheral structures were more difficult to assess by CTS. Peripheral bronchial diameter, BWT and diameter of accompanying artery could be assessed by CTS in 20, 15 and 4 cases, respectively and mean difference between measurements was −0.5 (SD 0.5), −0.3 (SD 0.3) and −0.4 (SD 0.4) mm, respectively. Conclusion: This study indicates that peripheral structures are more difficult to evaluate by CTS and that CTS slightly underestimate size of structures in comparison to CT
|
|
| 5. |
- Asplund, Sara, 1976, et al.
(författare)
-
Extended analysis of the effect of learning with feedback on the detectability of pulmonary nodules in chest tomosynthesis
- 2011
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 7966
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In chest tomosynthesis, low-dose projections collected over a limited angular range are used for reconstruction of section images of the chest, resulting in a reduction of disturbing anatomy at a moderate increase in radiation dose compared to chest radiography. In a previous study, we investigated the effects of learning with feedback on the detection of pulmonary nodules in chest tomosynthesis. Six observers with varying degrees of experience of chest tomosynthesis analyzed tomosynthesis cases for presence of pulmonary nodules. The cases were analyzed before and after learning with feedback. Multidetector computed tomography (MDCT) was used as reference. The differences in performance between the two readings were calculated using the jackknife alternative free-response receiver operating characteristics (JAFROC-2) as primary measure of detectability. Significant differences between the readings were found only for observers inexperienced in chest tomosynthesis. The purpose of the present study was to extend the statistical analysis of the results of the previous study, including JAFROC-1 analysis and FROC curves in the analysis. The results are consistent with the results of the previous study and, furthermore, JAFROC-1 gave lower p-values than JAFROC-2 for the observers who improved their performance after learning with feedback. © 2011 SPIE.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
