BackgroundrnThe thyroid gland, located between C5 and T1 vertebrae, is a butterfly shaped endocrine glandrnwhich is divided into two lobes and connected by an isthmus [1]. Along with the breast, lung andrnbone marrow, thyroid gland is among the most sensitive organs for radiation due to their rapidrncell division [2].rnrnThe potential risk factors for thyroid carcinoma development include genetic predisposition,rnexposure to therapeutic or environmental ionizing radiation, residence in areas of iodinerndeficiency or excess, history of preexisting benign thyroid disease, as well as hormonal andrnreproductive factors. [3]rnrnThe radiation dose (mGy) towards the thyroid gland is greater during Chest CT as compared tornHead CT and Paranasal sinus CT. The association between radiation exposure and thernoccurrence of thyroid cancer has been well documented, and the two main risk factors for therndevelopment of a thyroid cancer are the radiation dose delivered to the thyroid gland and the agernat exposure. The risk increases after exposure to a mean dose of more than 0.05-0.1 Gy (50100mGy).rnrnThe risk is more important during childhood and decreases with increased age atrnexposure, being low in adults [4].rnrnObjectivernThis study is designed to assess the rate of unnecessary radiation exposure to the thyroid gland inrnpatients who presented to radiology department and had Computed Tomography of the chest atrnTikur Anbessa Specialized Hospital.rnrnMethodrnHospital based retrospective cross-sectional study was conducted on 1306 patients who rnunderwent a chest CT at TASH and thyroid gland inclusion in these studies along with the CT rndose of the studies were evaluated over a period of 6 months from July 2018 to January 2019.rn rn rn7 rnData was collected by evaluating chest CT scans from PACS (Medweb). The data was checkedrnfor clarity and completeness. Computerized data analysis was conducted by using SPSS versionrn24.0 software.rnrnResultrn1803 Chest CT scans were done over a period of 6 months out of which, 341 were chest alongrnwith another body part (chest + abdomen, chest + head and neck, etc); 83 had missing variablesrn(such as DLP, CTDIvol and/or mean CTDI); 35 had thyroid pathology; 23 scans were done forrnCT guided biopsy purpose and 15 patients had scans done at least twice within this time framernfor which the most latest scan was reported and the others reported as â€˜previous CTâ€™s. These rndataâ€™s, in accordance with the exclusion criteria, were not included. rnrn1306 patient CT scan were included in this study over a period 6 months. Intravenous iodinatedrncontrast media was used in 95.4% of the CT scans. Thyroid was included in 99.8% of the scans,rnout of which 76.9% included the whole thyroid gland. 12.6% of the patients were scannedrnpreviously in addition to the current one. Among the patients who had previous CT scans, 75.3%rnhad one previous scan and 24.7% had two previous scans. rnrnFemale had lower scan length compared to male. There was a tendency for linear increment inrnscan length as age increases. The mean ED was slightly higher than the recommended ED of 57mSvrnwith,rnhowever,rn5%rn(calculatedrnby conversionrnfactorrnofrnICRPrn60) andrn7% (ICRPrn103)rnwerernrnexposedrnforrnhigherrnthanrnthernrecommendedrnEDrn(2-20mSv).