1-2_X_Tube_Gen_Introd_Triest_2012.pdfVIP

X-ray Tube and Generator – Basic principles and construction Dr Slavik Tabakov King’s College London H.V. X-ray Generator X-ray Tube X-ray stand (detector)H.V. X-ray Generator X-ray entrance Spectrum Object Patient X-ray exit Spectrum - Production of X-rays - X-ray tube construction - Anode - types, efficiency - X-ray tube working characteristics - Intensity of X-ray beam, housing and filtration - Classical X-ray generator (block diagram) - Medium frequency X-ray generator (block diagram) - Principle of radiographic contrast formation - X-ray film and film/screen combination - Mammographic contrast and X-ray tubes - Various radiographic contrasts (definitions) OBJECTIVES Approximately 90% of the total collective dose to UK population from man-made radiation sources arises from Diagnostic Radiology Safety in Diagnostic Radiology, IPEM, 1995 Patient radiation doses from diagnostic radiology, D Hart, 1996 In most industrialised countries there are between 300 and 900 X-ray examinations for every 1000 inhabitants every year. Over half of these are chest examinations (these figures does not include dental X-ray examinations or mass screening programs). Doses varies widely from hospital to hospital, even in the same country, sometimes by a factor of 100. Radiation and You, EU, Luxembourg 1990 1990, UK 2008 Estimated annual collective dose to UK population from Diagnostic Radiology (approx. figures): 1989 - 17,000 manSv; 1999 - 20,000 manSv (risk estimate approx. 700 cancer deaths/year); 2008 - 25,000 manSv Safety in Diagnostic Radiology, IPEM, 1995; UK population dose from medical X-ray examinations , D. Hart , B. F. Wall, 2002; Considerations for Radioactive Substances Regulation under the Radioactive Substances Act 1993 at nuclear sites in England and Wales, 2008 Collective dose to population from Diagnostic Radiology 100% 0.25% 1% 2% Distribution of X-ray dose from the Tube through the Patient to the X-ray film Exposure ~ 80 kV