Comparison of two methods for evaluation of the image quality of lumbar spine radiographs.

Two methods for visual evaluation of image quality of clinical radiographs have been compared. In visual grading analysis (VGA) specified anatomical structures in an image are visually compared with the same structures in a reference image, and in a free-response forced error (FFE) experiment - an extension of conventional ROC (receiver operating characteristics) analysis - the objective is to correctly localise known lesions. The spatial resolution and noise of digitised clinical radiographs of the lumbar spine were altered by image processing, and pathological structures were added to the images for the FFE experiment. The images were printed to film and evaluated by seven European expert radiologists using VGA and FFE. The results of these two different methods showed a very good agreement. In conclusion, VGA methodology can be made as solid as the FFE experiment for evaluating image quality. The simplicity of VGA makes it very suitable for implementation in clinical practice

<title>Influence of the characteristic curve on the clinical image quality and patient absorbed dose in lumbar spine radiography</title>

The 'European Guidelines on Quality Criteria for Diagnostic Radiographic Images' do not address the choice of film characteristic (H/D) curve, which is an important parameter for the description of a radiographic screen-film system. Since it is not possible to investigate this influence by taking repeated exposures of the same patients on films with systematically varied H/D curves, patient images of lumbar spine were digitised in the current study. The image contrast was altered by digital image processing techniques, simulating images with H/D curves varying from flat over standard latitude to a film type steeper than a mammography film. The manipulated images were printed on film for evaluation. Seven European radiologists evaluated the clinical image quality of in total 224 images by analysing the fulfilment of the European Image Criteria and by visual grading analysis of the images. The results show that the local quality can be significantly improved by the application of films with a steeper film H/D curve compared to the standard latitude film. For images with an average optical density of about 1.25, the application of the steeper film results in a reduction of patient absorbed dose by about 10-15% without a loss of diagnostically relevant image information. The results also show that the patient absorbed dose reduction obtained by altering the tube voltage from 70 kV to 90 kV coincides with a loss of image information that cannot be compensated for by simply changing the shape of the H/D curve

Influence of the characteristic curve on the clinical image quality of lumbar spine and chest radiographs.

The &quot;European Guidelines on Quality Criteria for Diagnostic Radiographic Images&quot; do not address the choice of the film characteristic (H&amp;D) curve, which is an important parameter for the description of a radiographic screen-film system. The image contrast of clinical lumbar spine and chest radiographs was altered by digital image processing techniques, simulating images with different H&amp;D curves, both steeper and flatter than the original. The manipulated images were printed on film for evaluation. Seven experienced radiologists evaluated the clinical image quality by analysing the fulfilment of the European Image Criteria (ICS) and by visual grading analysis (VGA) of in total 224 lumbar spine and 360 chest images. A parallel study of the effect of the H&amp;D curve has also been made using a theoretical model. The contrast (DeltaOD) of relevant anatomical details was calculated, using a Monte Carlo simulation-model of the complete imaging system including a 3D voxel phantom of a patient. Correlations between the calculated contrast and the radiologists&#39; assessment by VGA were sought. The results of the radiologists&#39; assessment show that the quality in selected regions of lumbar spine and chest images can be significantly improved by the use of films with a steeper H&amp;D curve compared with the standard latitude film. Significant (p&lt;0.05) correlations were found between the VGA results and the calculations of the contrast of transverse processes and trabecular details in the lumbar spine vertebrae, and with the contrast of blood vessels in the retrocardiac area of the chest

Demonstration of correlations between clinical and physical image quality measures in chest and lumbar spine screen-film radiography

The ability to predict clinical image quality from physical measures is useful for optimization in diagnostic radiology. In this work, clinical and physical assessments of image quality are compared and correlations between the two are derived. Clinical assessment has been made by a group of expert radiologists who evaluated fulfilment of the European image criteria for chest and lumbar spine radiography using two scoring methods: image criteria score (ICS) and visual grading analysis score (VGAS). Physical image quality measures were calculated using a Monte Carlo simulation model of the complete imaging system. This model includes a voxelized male anatomy and was used to calculate contrast and signal-to-noise ratio of various Important anatomical details and measures of dynamic range. Correlations between the physical image quality measures on the one hand and the ICS and VGAS on the other were sought. 16 chest and 4 lumbar spine imaging system configurations were compared in frontal projection. A statistically significant correlation with clinical image quality was found in chest posteroanterior radiography for the contrast of blood vessels in the retrocardiac area and a measure of useful dynamic range. In lumbar spine anteroposterior radiography, a similar significant correlation with clinical image quality was found between the contrast and signal-to-noise ratio of the trabecular structures in the L1-L5 vertebrae. The significant correlation shows that clinical image duality can, at least in some cases, be predicted from appropriate measures of physical image quality

The influence of different technique factors on image quality for chest radiographs : Application of the recent CEC image quality criteria.

The aim of the first this work part of the EU-project, Trial I, was to evaluate and possibly improve the CEC image criteria for radiographic chest images. Chest images of healthy volunteers were acquired using different technique factors. The image criteria were used as a tool to discriminate between the different images. The technique factors were chosen so that the image quality would differ slightly. Four different technique parameters, each with two possible settings, used in clinical practice today, were used: tube voltage - 102 and 141 kV; screen/film speed - 160 and 320; maximum optical density in the parenchyma - 1.3 and 1.8; method for scatter reduction - air gap 30/390 and moving grid40/12. The results showed that the image criteria were able to separate between different technique groups. Some conclusions can be drawn from the results Optical density 1.8 was better than 1.3 independent of the other parameters. . Among the six combinations ranked best , four used tube voltage 141 kV and four used air gap technique for scatter reduction. No difference was seen for screen/film speed. No correlation was seen between the ranking of the systems and patient dose

The Influence of Different Technique Factors on Image Quality for Chest Radiographs: Application of the Recent CEC Image Quality Criteria

The aim of the first this work part of the EU-project, Trial I, was to evaluate and possibly improve the CEC image criteria for radiographic chest images. Chest images of healthy volunteers were acquired using different technique factors. The image criteria were used as a tool to discriminate between the different images. The technique factors were chosen so that the image quality would differ slightly. Four different technique parameters, each with two possible settings, used in clinical practice today, were used: tube voltage - 102 and 141 kV; screen/film speed - 160 and 320; maximum optical density in the parenchyma - 1.3 and 1.8; method for scatter reduction - air gap 30/390 and moving grid40/12. The results showed that the image criteria were able to separate between different technique groups. Some conclusions can be drawn from the results Optical density 1.8 was better than 1.3 independent of the other parameters. . Among the six combinations ranked best , four used tube voltage 141 kV and four used air gap technique for scatter reduction. No difference was seen for screen/film speed. No correlation was seen between the ranking of the systems and patient dose

The influence of different technique factors on image quality of chest radiographs as evaluated by modified CEC image quality criteria.

The Commission of the European Communities (CEC) research project Predictivity and optimisation in medical radiation protection" addressed fundamental operational limitations in existing radiation protection mechanisms. The first part of the project aimed at investigating (1) whether the CEC image quality criteria could be used for optimization or a radiographic process and (2) whether significant differences in image quality based on these criteria could be detected in a controlled project with well known physical and technical parameters, In the present study. chest radiographs on film were produced using healthy volunteers. Four physical/technical parameters were varied in a carefully controlled manner: tube voltage ( 102 kVp and 14 1 kVp). nominal speed class (160 and 320). maximum film density (1.3 and 1.8) and method of scatter reduction (grid (R = 12) and air gap). The air kerma at the entrance surface was Measured for all patients and the risk-related dose H-Golem, based on calculated organ-equivalent dose conversion coefficients and the measured entrance air kerma values. was calculated, Image quality was evaluated by a group of European expert radiologists using a modified version of the CEC quality criteria. For the two density levels. density level 1.8 was significantly better than 1.3 but at the cost of a higher patient radiation exposure. The correlation between the number of fulfilled quality criteria and H-Golem was generally poor. An air gap technique resulted in lower doses than scatter reduction with a grid but provided comparable image quality. The criteria can be used to highlight optimum radiographic technique in terms of image quality and patient dose, although not unambiguously. A recommendation for good radiographic technique based on a compromise between image quality and risk-related radiation dose to the patient is to use 141 kVp. an air gap, a screen-film system with speed 320 and an optical density of 1.8.

Influence of the characteristic curve on the clinical image quality of lumbar spine and chest radiographs.

The "European Guidelines on Quality Criteria for Diagnostic Radiographic Images" do not address the choice of the film characteristic (H&D) curve, which is an important parameter for the description of a radiographic screen–film system. The image contrast of clinical lumbar spine and chest radiographs was altered by digital image processing techniques, simulating images with different H&D curves, both steeper and flatter than the original. The manipulated images were printed on film for evaluation. Seven experienced radiologists evaluated the clinical image quality by analysing the fulfilment of the European Image Criteria (ICS) and by visual grading analysis (VGA) of in total 224 lumbar spine and 360 chest images. A parallel study of the effect of the H&D curve has also been made using a theoretical model. The contrast ({Delta}OD) of relevant anatomical details was calculated, using a Monte Carlo simulation-model of the complete imaging system including a 3D voxel phantom of a patient. Correlations between the calculated contrast and the radiologists' assessment by VGA were sought. The results of the radiologists' assessment show that the quality in selected regions of lumbar spine and chest images can be significantly improved by the use of films with a steeper H&D curve compared with the standard latitude film. Significant (p<0.05) correlations were found between the VGA results and the calculations of the contrast of transverse processes and trabecular details in the lumbar spine vertebrae, and with the contrast of blood vessels in the retrocardiac area of the chest