Introduction: This study, evaluate pediatric digital radiography. Due to the high rates of this test and the high sensitivity of children to ionizing radiation in comparison with adults, it is attempted to achieve near optimal conditions by reducing the dose and maintaining the image quality. The object of the study is to change the irradiation parameters such as kV and mA and change them to a point where the dose is as high as possible for improved image quality or image quality preservation.
Materials and Methods: Irradiation data from 50 children were collected for each of 2 age groups 0-1and 1-5 years old, and the mean values of voltage, current, and tube-to-table distance were obtained. To investigate Improving image quality as the dose reduced, a homogeneous phantom was constructed to produce an equivalent chest distribution with less than 5% accuracy. The Monte Carlo simulation and the equivalent human phantom ORNL were used to make this phantom. Then, with use of a digital radiographic system and dosimetric instruments that calculate the dose, the dose of homogeneous phantom was measured. Subsequently, irradiation parameters such as kV and current were changed to provide voltages higher than reference voltage and lower current flow rates than those referring to a dose lower than the reference dose, the choice of these conditions is due to the decrease in absorption dose. Finally, three parameters MTF, SNR and CNR are measured using the tools designed in this phantom.
Results: With the results obtained for three parameters of each of the two age groups, the result was that for the age group 0-1, the best selection for the voltage and current was 60 and 2.5, respectively, in which the dose reduced and image quality increased. For 1 -5 years the voltage 75 with a current range of 3.2 to 5 mAs was close to optimum.
Conclusion: This article has determined wide variations in radiation dose of x-ray examinations. Also, to Reduce patient dose and enhance image quality is suggested following solutions:
1-               utilization of Automatic Exposure Control (Of course, it's not easy to use for children with small body)
2-               Used additional filters such as copper: This filter by removing low-energy beam makes the beam harder, and photoelectric effect reduced, as a result, the patient dose is reduced.
The works that was done in this study: Improving the exposure parameter compared to dose reference extracted 50 images for each age group and as well as improved its image quality.