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Abstract
Although x-rays have been widely used as the most important and reliable scientific
tool for effective proper diagnosis of diseases. Critical organs that present in or close to
irradiated area exposed during examination to a dose that might exceed its tolerance.
For superficial critical organs, these doses measured as Entrance Surface Dose (ESD)
by using Thermoluminescence dosimeters (TLDs).
The aim of this work was to estimate the Entrance Surface Dose (ESD) for superficial
critical organs of different radiographic examination modalities.
The materials used are Lithium fluoride chips (liF:Mg,Ti) TLD-100, Harshaw Model
4500TLD reader machine, Linear accelerator ”Elekta precise treatment system” with photon
energy 6 MV to calibrate TLD chips, ProOne Digital panoramic system, Toshiba Computed
radiography system (CR), DR Tech. Direct radiography system (DR), Computed tomography
“Siemens multi slices detector arrays with 6 scanners” and Computed tomography “Philips
multi slices detector arrays with 64 scanners”.
Head and neck region of 50 patients was scanned for panoramic study, CT brain
study, CR X-ray and DR X-ray radiography. TLDs were calibrated against a known exposure
measured by LINAC.TLD chips were placed inside plastic sachets on the skin of patients.
The sachets were placed on thyroid gland, left and right parotid glands, and eye lids.