Location of Shielding Material and Size of Radiation Field in Radiographic Procedures for Neurocranium Affect Entrance Surface Dose in Major Organs

Abstract

Objectives: The purpose of this study was to determine the effect of the location of cylinder thyroid shielding materials and the size of radiation field in radiographic procedures for neurocranium on entrance surface dose in major organs.Methods/Statistical Analysis: Two SID (100cm and 70cm) of DR system with exposure conditions at 76 kVp and 25 mAs were used. ESD was measured by using OSLD and ART phantom with maximum radiation field of and 8 inch x 10 inch.Measurement points included the left, the right, the anterior and the posterior of the thyroid area using thyroid shielding. Findings: The ESD values of maximum field at the back shield were lower (SID 100cm and 70cm: 85.9% and 63.4% lower,respectively) than those at the front shield. For 8 inch x 10 inch field, the ESD values were lower by 64% and 54.3% for SID 100 cm and 70 cm, respectively. The ESD values when the cylinder device was used were lower by 67% and 27.6% for SID 100 cm and 70 cm, respectively. In addition, for SID 100 cm, the orbit ESD with maximum field was the highest (200.62uSV). Orbit ESD value was lower by 54.4% (91.57 uSV) for a field of 8 inch x 10 inch. It was also lower by 57% (86.28 uSV) when cylinder device was used. For SID of 70 cm, orbit ESD value with the maximum field was the highest (262.18 uSV).It was lower by 28% (188.87 uSV) than that for a field of 8 inch x 10 inch. It was also lower by 64% (94.59 uSV) when the cylinder was used. Improvements/Applications: Using cylinder device and back shielding for the thyroid could reduce ESD in sensitivity organs of patients.