PENGARUH RASIO GRID TERHADAP KUALITAS RADIOGRAF FANTOM KEPALA

Abstract

This study aims to determine the effect of the grid ratio on the quality of the radiographic examination of a head phantom. The study was conducted by using grid ratios of 5:1, 6:1, and 8:1, the head phantom. The focus-film distance (FFD) was 100 cm. In the antero-posterior projection used voltages of 70, 75, and 80 kVp with a current-time of 25 mAs, while in the lateral projection using voltages of 65, 70 and 75 kVp with a current-time of 20 mAs. The densities of radiographs were measured using a densitometer. Measurement was repeated in 10 locations. The contrast of radiograph was calculated as the difference between adjacent density values. The results showed that the higher level of the grid ratio would lower the density of radiograph, however it does not always give effect to the increase or decrease the contrast of radiographs. It was found that the optimal quality radiographs in antero-posterior projection at a grid ratio of 6:1 for tube voltage of 75 kVp with a current-time of 25 mAs, and in the lateral projections at a grid ratio of 5:1 grid for tube voltage of 75 kVp with a currenttime of 20 mAs.