Abstract
Various combinations of tube voltage and grid ratio were examined to, satisfy the following conditions in high voltage techinique of the chest.
Comparable or better findings concerning the fine petails of soft tissues, calcification and minor blood vessels underlying ribs in comparison with 60 kVp without rid were obtained in the voltage ranging from 80 to 140 kVp. Quantitative determinations of patient's exposure were carried out, which was one of the important factors in the improvement of chest radiography.
Results were as follows :
1. To secure the findings of fine details of soft tissue, it is only necessary to combine the grid of low ratio with high voltage.
2. Combination of high voltage and high grid ratio is preferable for the observation of the fine details of blood vessels underlying ribs.
3. For calcification, low voltage and low grid ratio is desirable.
4. Combination of high voltage and low grid ratio can improve radiogram and reduce patient's exposure time.
5. In general, various combinations of voltage and grid ratio can be adopted as standard in routine work : 80 kVp and 4: 1, 100 kVp and 6: 1, 120 kVp and 8: 1, 140 kVp and 12: 1, 140 kVp and 5: 1 cross grid.
