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

 

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(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

 

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(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

 

 

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(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.