Examination of the personal dosimetry records of the past five years from 2012 to 2016 is conducted and average radiation doses received by the staff are calculated including the total accumulated last 5 years doses. The radiation doses were measured using thermo luminescence dosimeters (TLD). The total number of monitored staff was 538 and 274 from our medical center and from the other centers that we cover respectively. RESULTS: The levels of occupational exposures in our hospital and other medical institutions compares very well with the internationally and nationally reported results. The annual average for the five years period under examination in this work was 0.4, 0.8 and 0.5 mSv for the diagnostic radiology, nuclear medicine and radiation therapy groups respectively. Our minimal detection limit for personal dosimetry reporting is 0.1 mSv. CONCLUSIONS: The results of the measured annual doses were well below the ICRP recommended annual dose limit of 20 mSv. Our results compare very well with the UNSCEAR 2008 report. In general the application of ionizing radiation in Medicine is a safe practice for the occupationally exposed workers.

Purpose: During computed tomography (CT) helical scanning mode the patient surface dose distribution is assumed to be non-uniform, therefore point dose measurement methods may lead to imprecise estimation of the radiation dose received by the patient skin in particular. We have used XRQA2 films as in-vivo dosimeters to measure the entrance skin dose during sinus exams. Methods: The films were placed under the patient head rest in order to sample the entrance surface dose in-vivo. We have performed in-vivo film irradiation on 23 patients in this study to verify the clinical suitability of the method and were found adequate. Results: The measured average ESD in the sinus exam was 11.7 ± 1.0 mGy, the PSD was 15.7 ± 1.7 mGy and the CTDI (vol) was 13.3 ± 0.1 mGy. The ratio of ESD/CTDI (vol) and PSD/CTDI (vol) was 0.88 and 1.18 respectively. The results indicate that the scanner registered CTDI (vol) underestimates the PSD and in the same time it overestimates the ESD by 18% and 13.6% respectively. Conclusion: The observed differences between the ESD, PSD and CTDI (vol) although seem small for the radiation dose range measured during CT of the sinus [13.2-13.4] mGy, but important for the medical physicist to know, since monitoring of patients' doses from CT examinations is becoming more mandatory. The use of radiochromic film as in-vivo dosimeter does not interfere with the clinical radiological exam and does not produce any image artifacts. The method can be used to study other CT examinations specially the ones with large beam width, high pitch factor and high dose exams. The method allows measurement of the peak skin dose, examination of the CT dose profile and the 2D dose distribution in the XZ plan.

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