s / Physica Medica 30 (2014) e75ee121 e118 Fig.3. Mean values of the G-SSIM index for the two diameters used and two different nominal attenuation values. Images were obtained at 64-slice scanner using three acquisition modes and 60 bpm heart rate. ESTABLISHMENT OF LOCAL DIAGNOSTIC REFERENCE LEVELS AT “THEAGENEIO” CANCER HOSPITAL OF THESSALONIKI S.G. Chanlaridis , M. Chatzimarkou , A. Makridou , N. Servitzoglou , E. Soidou , S. Stoulos . Aristotle University of Thessaloniki, Department of Physics, Section of Nuclear & Elementary Particle Physics, GR-541 24, Thessaloniki, Greece; b Theageneio Hospital for Cancer Treatment, Department of Medical Physics, GR-546 39, Thessaloniki, Greece Motivation: Estimation of doses received by patients undergoing radiological examinations for establishing local diagnostic reference levels (LDRL) for routine procedures of diagnostic radiology department along with minimization of patients' radiation exposure. The obtained results were compared with the national values of DRL provided by the Greek Atomic Energy Commission (GAEC) for the audit of malpractice in this department. Materials and methods: Numerous parameters were measured for a large sample of patients undergoing radiography exams and CT scans. The mean value of these parameters was selected for irradiation of patients and measurement of the delivered dose. A standard ionization chamber was selected to measure the suitable dosimetric quantity. For Radiography exams the dosimetric quantity that was measured was the air-kerma at a distance of 1 meter from the source. The entrance skin dose was calculated by multiplying the obtained air-kerma value with suitable backscatter factors and correcting according to the inverse square law for the standard patient’s dimensions. For CT exams the dosimetric quantities that were measured were the weighted Computerized Tomographic Dose Index (CTDIw) and the Dose Length Product (DLP) for one acquisition and a complete examination. Results: For the two operating radiographic units the doses in term of entrance surface air-kerma are as follows: Rad. UnitExam CPI CPM 200DR BMI BRG 200R MERATE MERATE Chest Radiograph (PA) 0,297 mGy 0,284 mGy Chest Radiograph (LAT) 1,28 mGy 1,259 mGy Lumbar Spine Radiograph (PA) Not enough data 4,06 mGy Lumbar Spine Radiograph (LAT) Not enough data 6,938 mGy