15% kVp Rule Effect on CR Exposure Index: An Initial Phantom Study

Abstract

In using the Computed Radiography (CR), radiographers usually carry out abdomen examinations with different exposure factors without any definite reference or standard, by setting higher kV and higher mAs. Without realizing it, this will certainly affect the Exposure Index as a dose indicator indirectly on Computer Radiography. It is necessary to have an appropriate standard for calculating the exposure factor to control the Exposure Index value in order to produce Exposure Index / within a safe range. This research was conducted using descriptive quantitative methods at the Bali ATRO Laboratory which was conducted in April 2020. The sample in this study was a water phantom which is equivalent to the abdominal organs of a normal person. From the results of research and data analysis, it can be concluded that in First variation 1 with 77 kV and 8 mAs show 332.4 average exposure index, in the second variation with 89 kV and 4 mAs, the average exposure index was 313.6, and the third variation with 65 kV and 16 obtained 335.6 average exposure index. From the results obtained, it allows flexibility in the use of combinations of exposure factors as needed. 15% increased kVp variation can be used for taking action on non-cooperative patients which can help minimize unsharpness and repetition caused by patient movement. 15% reduced kVp is good for extremities and certain examinations that require optimal detail.