Limitation of Radiation Dose Exposure with the Selection of Radiography Grid Ratio

Abstract

Background
The higher value of the grid ratio, the greater radiation absorbed by the grid strip, thus affecting the use of exposure factors on radiographic examinations. Increased exposure factors may cause an increase in radiation doses in patients.
Objective
This study aims to determine the grid ratio that produces optimal radiographic contrast (gamma) with a low dose.
Methods
The sample used 3 grid ratios of 1:5, 1:6, 1:8, and 1:10. The grid was exposed by placing on it a container filled with water with a water height of 10 cm. Step wedge was placed in water as high as 5 cm from the bottom of the container. Radiographic contrast was measured from gamma on a straight line curve. Samples were exposed with 70 kV, 75 kV, 80 kV, 85 kV, 90 kV and the radiation doses were measured. Statistical tests was conducted include grid ratio correlation test with gamma value, gamma value difference test, and EI index deviation test with tube tension.
Results
There was a significant difference between gamma value with the grid ratio of 1:5 (p <0.05) with 1:6, 1:8 and 1:10. There was no significant difference (p> 0.05) between gamma value with the grid ratio of 1:6 with 1:8 and 1:10. Increasing the grid ratio from 1:6 to 1:8 caused an increase in radiation dose adjustment by 22.35%.
Conclusions
It was concluded that grid ratio of 1:6 was capable of producing optimal radiographic contrast with a minimal radiation dose.