بررسی پرتوگیری تیرویید در سی تی اسکن مغز و رادیوگرافی معمول جمجمه با اعمال مقادیر مختلف شدت جریان و اختلاف پتانسیل با و بدون استفاده از شیلد تیرویید

Background and aim: nowadays, thyroid exposure is a major concern in skull radiological imaging. the aim of this study was to evaluate thyroid exposure in brain ct-scan and skull x-ray, using different levels of kvp (kilovoltd peak) and ma, with and without thyroid shield.methods: in this descriptive- analytic study, 350 outpatients were selected randomly. two tld-100 chips (thermo luminescence dosimeter) were placed on the thyroid of each patient. three levels of ma were applied in brain ct-scan (210 patients) and two levels of kvp were used in routine skull x-rays (140 patients). the experiments were performed with and without thyroid shield. the tlds were read and the statistical analysis was performed using student-t test.results: during brain ct-scan, decreasing current intensity from 150 to 125 ma, significantly decreased the thyroid exposure from 101±9.38 to 82.2±8.04 mili rem (p < 0.01). using a thyroid shield extremely reduced the thyroid exposure to 29±5.83 mili rem (p < 0.01). in routine skull x-rays, increasing voltage from 60 to70 kvp, significantly decreased the thyroid exposure from 72.6±7.74 to 67±8.41 mili rem (p < 0.05). moreover, using the thyroid shield remarkably reduced the thyroid exposure to 19.6±1.82 mili rem (p < 0.05).conclusions: using lower levels of ma in brain ct-scans and higher levels of kvp in skull x-rays, decrease thyroid exposure. furthermore, using thyroid shield during x-ray examinations of the skull remarkably reduces thyroid exposure.