This unit addresses scientific and technical principles of diagnostic ultrasound and the scanning modes. The fundamentals of ultrasound transducers, continuous-wave and pulse-wave high frequency sound, A-mode, M-mode and B-mode diagnostic ultrasound scanning, the Doppler effect, spectral Doppler, colour and power Doppler and associated instrumentation are introduced. Recent developments in harmonic imaging and the use of contrast agents are presented. Safety issues are also covered including an understanding of bio-effects and bio-hazards. Students will develop skills in the recognition of image artefacts, the implementation of a quality assurance program and in optimising image quality.