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Dosimetry for mammography DS /CM/JlH IAEA International Atomic Energy Agency Mammography dosimetry • Measurements using phantoms • Measurements on patients Kampala 2 Mean glandular dose (MGD or Dg) - UK • 5.3 cm standard breast. • DG = g53 c53 s Ki • g53 c53 determined by computer • s depends on targets and anodes • Ki IAK b 2a Kampala 3 Mammography equipment • 45 mm thick PMMA phantom for use in breast dosimetry • Use of a multi-slab phantom allows the possibility of measurements at thickness other than 45 mm INTERNATIONAL ELECTROTECHNICAL COMMISSION, Medical Electrical Equipment Dosimeters with Ionization Chambers and/or Semi-conductor Detectors as used in X-Ray Diagnostic Imaging, IEC-61674 Kampala 4 Measurements on Patients • Measuring the mean glandular dose to the standard breast has for many years been the main means of assessing the doses from mammographic systems. • Although this is a valuable and simple approach to dose measurement it provides limited information on the doses received by individual women. • Consequently the periodic measurement of doses for samples of women undergoing mammographic examinations is recommended in the UK by the NHSBSP. Kampala 5 Selection of patients • • Kampala For each patient and patient exposure record the following data: selected target/filter combination, tube voltage, tube loading (post exposure mAs) and indicated breast thickness. Data should be recorded separately for left and right breasts and the radiographic projection used for each exposure should be noted. Collect data for the required series of patients. 6 Calculations for each patient case DG =gc s Ki Kampala 7 Results – Perth Royal Infirmary Kampala 8 NHS BSP Software Kampala 9 Scottish National Picture Kampala 10
