Evaluation of image quality of lumbar spine images: a comparison between FFE and VGA

PURPOSE: The aim of the present study is to compare two different methods for evaluation of the quality of clinical X-ray images. METHODS: Based on fifteen lumbar spine radiographs, two new sets of images were created. A hybrid image set was created by adding two distributions of artificial lesions to each original image. The image quality parameters spatial resolution and noise were manipulated and a total of 210 hybrid images were created. A set of 105 disease-free images was created by applying the same combinations of spatial resolution and noise to the original images. The hybrid images were evaluated with the free-response forced error experiment (FFE) and the normal images with visual grading analysis (VGA) by nine experienced radiologists. RESULTS: In the VGA study, images with low noise were preferred over images with higher noise levels. The alteration of the MTF had a limited influence on the VGA score. For the FFE study, the visibility of the lesions was independent of the sharpness and the noise level. No correlation was found between the two image quality measures. CONCLUSIONS: FFE is a precise method for evaluation of image quality, but the results are only valid for the type of lesion used in the study, whereas VGA is a more general method for clinical image quality assessment. The results of the FFE study indicate that there might be a potential to lower the dose levels in lumbar spine radiography without losing important diagnostic information.     

Planning - topography and climate

The presentation of local climatic data has wide-reaching effects for planners, designers and those living and working in an area, report Sven Lindqvist and Jan O. Mattsson of the Department of Geography at the University of Lund.     

Nodule detection in digital chest radiography: introduction to the RADIUS chest trial

Most digital radiographic systems of today have wide latitude and are hence able to provide images with a small constraint on dose level. This opens up for an unprejudiced dose optimisation. However, in order to succeed in the optimisation task, good knowledge of the imaging and detection processes is needed. As a part of the European-wide research project 'unification of physical and clinical requirements for medical X-ray imaging'-governed by the Radiological Imaging Unification Strategies (RADIUS) Group-a major image quality trial was conducted by members of the group. The RADIUS chest trial was focused on the detection of lung nodules in digital chest radiography with the aims of determining to what extent (1) the detection of a nodule is dependent on its location, (2) the system noise disturbs the detection of lung nodules, (3) the anatomical noise disturbs the detection of lung nodules and (4) the image background and anatomical background act as pure noise for the detection of lung nodules. The purpose of the present paper is to give an introduction to the trial and describe the framework and set-up of the investigation.     

Application of the finite element method to machinery

The finite element method has given the designer of machinery components and structures a new tool for analysis of stresses, temperatures and dynamic vibrations.In the following some applications of the tool to different problems within this field are shown (by some examples), using the SESAM-69 complex.Three-dimensional solids as well as three-dimensional plate and bar structures are treated, and the results are compared to analytical or experimental solutions where such are known.These examples should verify the FEM as very attractive to the modem machinery-designer.     

Perceived and actual change in job satisfaction.

Analysis of identified questionnaire data collected from 196 office employees at the start and end of a 6-mo period showed that change in overall job satisfaction as perceived at the end was a very poor, though statistically significant, proxy measure of change as computed from initial and terminal reports on levels of satisfaction. Perceived change in job satisfaction had zero regression on initial satisfaction but regressed very significantly on terminal satisfaction and on change in 14 job aspects as perceived at the end of the period. The findings cast serious doubts on the usefulness of the quasilongitudinal design in studies of the impact of technological and organizational changes upon job satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A dense network sub-grouping algorithm for co-citation analysis and its implementation in the software tool Sitkis

Summary Clustering algorithms are used prominently in co-citation analysis by analysts aiming to reveal research streams within a field. However, clustering of widely cited articles is not robust to small variations in citation patterns. We propose an alternative algorithm, dense network sub-grouping, which identifies dense groups of co-cited references. We demonstrate the algorithm using a data set from the field of family business research and compare it to two alternative methods, multidimensional scaling and clustering. We also introduce a free software tool, Sitkis, that implements the algorithm and other common bibliometric methods. The software identifies journal-, country- and university-specific citation patterns and co-citation groups, enabling the identification of “invisible colleges.”