6.5 Medical Imaging
6.5.1 Using X-rays
Learners should be able to demonstrate and apply their knowledge and understanding of:
(a) basic structure of an X-ray tube; components – heater (cathode), anode, target metal and high voltage supply
(b) production of X-ray photons from an X-ray tube
(c) X-ray attenuation mechanisms; simple scatter, photoelectric effect, Compton effect and pair production
(d) attenuation of X-rays; where μ is the attenuation (absorption) coefficient
(e) X-ray imaging with contrast media; barium and iodine
(f) computerised axial tomography (CAT) scanning; components – rotating X-tube producing a thin fan-shaped X-ray beam, ring of detectors, computer software and display
(g) advantages of a CAT scan over an X-ray image.
6.5.2 Diagnostic methods in medicine
Learners should be able to demonstrate and apply their knowledge and understanding of:
(a) medical tracers; technetium–99m and fluorine–18
(b) gamma camera; components – collimator, scintillator, photomultiplier tubes, computer and display; formation of image
(c) diagnosis using gamma camera
(d) positron emission tomography (PET) scanner; annihilation of positron–electron pairs; formation of image
(e) diagnosis using PET scanning
6.5.3 Using Ultrasound
Learners should be able to demonstrate and apply their knowledge and understanding of:
(a) ultrasound; longitudinal wave with frequency greater than 20 kHz
(b) piezoelectric effect; ultrasound transducer as a device that emits and receives ultrasound
(c) ultrasound A-scan and B-scan
(d) acoustic impedance of a medium;
(e) reflection of ultrasound at a boundary;
(f) impedance (acoustic) matching; special gel used in ultrasound scanning
(g) Doppler effect in ultrasound; speed of blood in the patient; for determining the speed v of blood.