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- Båth, Magnus, 1974, et al.
(författare)
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Nodule detection in digital chest radiography: effect of anatomical noise.
- 2005
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 109-13
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Tidskriftsartikel (refereegranskat)abstract
- The image background resulting from imaged anatomy can be divided into those components that are meaningful to the observers, in the sense that they are recognised as separate structures, and those that are not. These latter components (reffered to as anatomical noise) can be removed using a method developed within the RADIUS group. The aim of the present study was to investigate whether the removal of the anatomical noise results in images where lung nodules with lower contrast can be detected. A receiver operating characteristic (ROC) study was therefore conducted using two types of images: clinical chest images and chest images in which the anatomical noise had been removed. Simulated designer nodules with a full-width-at-fifth-maximum of 10 mm but with varying contrast were added to the images. The contrast needed to obtain an area under the ROC curve of 0.80, C0.8, was used as a measure of detectability (a low value of C0.8 represents a high detectability). Five regions of the chest X ray were investigated and it was found that in all regions the removal of anatomical noise led to images with lower C0.8 than the original images. On average, C0.8 was 20% higher in the original images, ranging from 7% (the lateral pulmonary regions) to 41% (the upper mediastinal regions).
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- Börjesson, Susanne, 1957
(författare)
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Computer Modelling of the Interaction between Water and Complex Solid Phases
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this work the program package PASSIPHIC is described. The program has been developed to calculate the equilibrium for an aqueous phase in contact with a complex solid. The complex solid is considered as consisting of pure minerals and /or solid solutions. Cement has been used as an example. Cementitious materials are likely to be present in large quantities in repositories for radioactive waste. The chemistry in the vicinity of such a repository will hence be influenced by the cement. Cement has been shown to serve as an immobiliser of many elements due to its high internal pH (> 12.5), large surface area and the ability of the hydrated phases in the cement matrix to incorporate radionuclides. Thus, the modelling of the evolution of cement-water interaction is an important factor in determining the release rates of radionuclides from a repository for radioactive waste. The PASSIPHIC program has been used to simulate leaching of cement with non-saline groundwater and the result is compared to experimental data. The agreement between experimental and calculated data has been found to be good.
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