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293Regarding published studies on evaluation radiation doses for CT examinations Kanal et al 38 calculated the DRLs and median values of CTDIvol and DLP for CT from 1310727 of ten most common examinations in the United States They found an insignificant relation between the patient size and DRLs and achievable doses for head and neck examinations however the CTDIvol DLP and DRLs increased with patient s size for body examinations Toori et al 39 establishes local reference levels for patients undergoing common CT examinations Including chest sinus brain pelvic and abdomen in Iran They reported differing values of the DLP CTDIw and CTDIvol for the same examination among different centers For example the CTDIw for pelvic was ranged from 7 to 16 3 and the DRLs defined to be 11 mGy In 2014 Alzimami 40 assessed the dose in 182 paediatric patients undergoing abdomen chest and brain helical CT examinations in Sudan The range of age in Alzimami study range between one month and ten years and weight between 5 and 29 kg They reported a highest value of DLP for the brain with 321 mGy cm effective dose 2 05 mSv and found a significant relation between patient dose and technologist experience and CT protocol Concerning published studies on evaluation radiation doses during routine fluoroscopy examinations Wambani et al 41 reported 83 of kerma area product for 455 adult patients using the integrated measuring system were below international DRLs and 60 of 195 paediatric patients below international DRLs except the examination performed with longtime found to be above international DRLs
The quality of image will include evaluating the following CT number slice thickness position alignment CT number uniformity low and high contrast resolution The radiation dose in terms of MGD will be evaluated for all mammography systems in all hospitals with the same method described by Perry et al 24 The description of this method was explained below The standard breast can be simulated using 5 cm thickness of PMMA however it s recommended to calculate the glandular dose for different PMMA thicknesses The exposure parameters such as kVp mAs target and filter material in the automatic exposure control mode should be recorded after exposing 2 3 4 4 5 5 6 and 7 cm thickness of PMMA The average glandular dose AGD can be calculated to typical PMMA thickness by the following equation AGD Ka i g c s
