Dose Reduction to the Thyroid Gland in Pediatric Chest Radiography

Authors

1 Medical Physics Student (MSc), Department of Medical Physics, Student Research Committee, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

2 Assistant Professor, Department of Medical Physics, School of Medicine, Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

3 Assistant Professor, Department of Medical Physics, Lorestan University of Medical Sciences, Khorram Abad, Iran.

4 Assistant Professor (PhD), Department of Oral and Maxillofacial radiology, School of dentistry, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

5 Radiologist, Department of Radiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

Abstract

Background
 It is remain a main concern that pediatric chest radiographies contribute to the significant radiation exposure to the thyroid gland as a more susceptible organ to radiation induced cancer. The aim of this study was to evaluate the entrance surface dose (ESD) of pediatric chest radiography compared to the diagnostic reference levels (DRL) and evaluation the efficacy of the lead (Pb) shield in radiation dose reduction to the thyroid gland.
Materials and Methods
After assessing each patient against specific inclusion-exclusion criteria, 40 pediatric patients who were undergoing anterior-posterior (AP) projection of the chest x-ray were considered eligible for this study. The ESD of the chest and also ESD of thyroid gland with and without a 1 mm butterfly-shaped lead shield which placed on the thyroid gland were measured using high sensitive thermo luminescent dosimeters (TLD-GR 200).
Results
The average of ESD for chest radiography was 0.068+ 0.006 mGy (0.021 - 0.232 mGy). The unshielded average thyroid ESD was 0.065 + 0.003 mGy compared to the shielded average thyroid ESD of 0.001 + 0.0005 mGy. The use of Pb-shield produced a statistically significant decrease in the average thyroid dose by about 97% (P< 0.001).
Conclusion
The use of Pb-thyroid shield in the AP projection of pediatric chest radiography has potential to reduced radiation dose without compromising image quality.

Keywords