1. X-ray imaging Radiography Photographic plate or digital detector X-ray machine X-rays absorbed by dense parts of patients body White indicates dense parts of body Grey indicates less dense regions Radiograph Patient image used with permission of Jens Langner, adapted from: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-23509

2. X-ray imaging X-rays Radio wavesInfraredVisible Ultraviolet X-rays/Gamma rays Increasing wavelength electrons Cathode Anode X-rays + High voltage Evacuated glass tube

3. X-ray imaging Computerised tomography (CT) Play X-ray source Detectors Patient image used with permission of Jens Langner, adapted from: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-23509

4. X-ray imaging X-ray dose Effective dose0.02 mSv6.6 mSv Equivalent background exposure3.5 days 3.1 years IonisationChest radiographChest CT image Sources of background radiation (UK) Radon gas from ground Food and drink Buildings and the ground Medical X-rays Cosmic rays Schools and colleges lecture