Investigation of grid performance using simple image quality tests
kVp-mAs contrast relationship by Sandy Everage - February 24, hangman, crossword, word scramble, games, matching, quizes, and tests. Describe the relationship between exposure time and density, Directly proportional mAs. What is the relationship between kVp and scatter? Directly proportional. Antiscatter grids improve the X-ray image contrast at a cost of patient radiation doses. The aim of this work is to understand the relation between grid performance . Reproducibility of X-ray exposure and accuracy of the kVp settings were.
Although the removal of the grid is recommended for some cases, especially for the fluoroscopic pediatric examinations, it is not frequently done in the routine work because of practical limitations. Adjustment of image contrast in these systems gives the user an option to remove the grid when the patient radiation dose becomes critical.
Some predictions can be made for patient dose image quality optimization from the grid parameters for some adult patient examinations, but this becomes more difficult for pediatric patients because of their thinner body parts and higher radiation sensitivities. It is also not easy to define a range of patient thickness where removal of grid is suggested. In digital radiology and fluoroscopy, flexibility of using different type of grids in one system or making the examinations without any grid require better understanding of the grid parameters by the users.
Grid manufacturers specify their products with grid pattern, focus range, grid ratio, strip density, cover, and inter-space materials.
The performance characteristics of grids are given by some other parameters. However, performance of a specific grid for a particular examination cannot be predicted from these data alone. Evaluation of grid specifications may assist the users to have a relative idea about the patient dose-image quality optimization for the selection of a specific grid. Although manufacturers make recommendations for the appropriate grids to be used for the clinical applications, it is the responsibility of users to select the optimum grid for their specific clinical procedure and to implement the examination with or without grid in the case of pediatric examinations.
The aim of this work is to understand the relation between grid performance parameters and some numerical image quality metrics for digital fluoroscopic examinations. We also investigated if any information can be obtained from the use of these metrics regarding the prediction of grid efficiency, especially for pediatric examinations. For this purpose, grid parameters were measured together with some image quality metrics for different acquisition geometries. To find the grid parameters, primary, scatter, and total radiation were measured using four grids with different grid ratios, strip densities, and cover materials for various scatter thicknesses and tube voltages, using the acquisition geometries suggested by International Electrotechnical Commission IEC and grid parameters mentioned above were calculated.
These results were evaluated to determine the relation between grid parameters and image quality metrics. In addition, the variation of grid parameters as a function of scatter thicknesses and tube voltage were investigated.
Patient thickness ranges that can be examined with or without grid for pediatric examinations are also suggested.
Materials and Methods A prototype digital fluoroscopy unit dedicated for research and training purposes was used in this study. The system is equipped with an amorphous silicon flat panel of Focus to chamber distance of cm was kept constant for all the measurements.
The X-ray tube voltage was set to 70, 90, and kVp. The range of densities the image receptor is capable of recording. How does mAs affect radiographic contrast Under or over exposure How does focal spot size affect radiographic contrast No influence.
- Effect of mAs and kVp on resolution and on image contrast.
- Investigation of grid performance using simple image quality tests
- There was a problem providing the content you requested
How does the anode heel effect affect radiographic contrast? Little effect How does filtration affect contrast? How does beam restriction collimation affect contrast? How do grids affect contrast?
What are two types of motion? Give an example of involuntary motion.
By a factor of 4 inversely. What are the seven types of radiologic tissue types. The overall blackness on the image.
Free Radiology Flashcards about Radiographic Exposur
Also described as the amount of black metallic silver on a film. Unwanted density on the film. Source to image distance SID Low radiographic contrast is called?