1. IAEA International Atomic Energy Agency RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY Part 15.8: Optimization of protection in radiography Practical exercise - Grid IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

2. IAEA 15.8: Optimization of protection in radiography2 Contents/Overview Subject matter : quality control of general radiography system Step by step procedure to be followed to assess the grid performance Interpretation of results

3. IAEA International Atomic Energy Agency Part 15.8: Optimization of protection in radiography Grid (system factor, homogeneity) IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology

4. IAEA 15.8: Optimization of protection in radiography4 What Minimum Equipment is Needed? Dosimeter Acrylic 20 cm thick Densitometer

5. IAEA 15.8: Optimization of protection in radiography5 Antiscatter grid - grid system factor (I) The grid system factor can be measured with a dosimeter Produce two images, one with and one without the grid system Use manual exposure control to obtain images with an optical density of about 1.00.

6. IAEA 15.8: Optimization of protection in radiography6 Antiscatter grid - grid system factor (II) The first image is made with the cassette in the bucky tray (with grid system) and acrylic on top of the table, and the second with the cassette on top of the table (without grid system) and acrylic on top of the cassette

7. IAEA 15.8: Optimization of protection in radiography7 Antiscatter grid - grid system factor (III) The grid system factor is calculated by dividing the exposures, corrected for the inverse square law and optical density differences Limiting value :Grid system factor  3. Frequency :Initially and when dose or exposure time increases suddenly

8. IAEA 15.8: Optimization of protection in radiography8 Grid imaging To assess the homogeneity of the grid in case of suspected damage or looking for the origin of artefacts, the grid may be imaged by automatic exposure of the bucky at the lowest position of the AEC-selector, without any added acrylic In general, this gives a good image of the gridlines

9. IAEA Where to Get More Information 15.3: Optimization of protection in radiography9 Quality Control in Diagnostic Imaging, Gray JE, Winkler NT, Stears J, Frank ED. Available at no cost. http://www.diquad.com/QC%20Book.html