MEDICAL+IMAGING

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Define the terms //attenuation coefficient// and //half-value thickness//.

Students may study these concepts in the context of a parallel beam of X-rays but should appreciate their wider application.

Derive the relation between attenuation coefficient and half-value thickness.

Solve problems using the equation Students may use simulation exercises to study X ‑ ray attenuation.

Describe X ‑ ray detection, recording and display techniques.

Students should be aware of photographic film, enhancement, electronic detection and display.

Explain standard X ‑ ray imaging techniques used in medicine.

Students should appreciate the causes of loss of sharpness and of contrast in X ‑ ray imaging. They should be familiar with techniques for improving sharpness and contrast.

Outline the principles of computed tomography (CT).

Students should be able to describe how a three ‑ dimensional image is constructed.

Describe the principles of the generation and the detection of ultrasound using piezoelectric crystals.

Define //acoustic impedance// as the product of the density of a substance and the speed of sound in that substance.

Solve problems involving acoustic impedance.

Students should understand the use of a gel on the surface of the skin.

Outline the differences between A ‑ scans and B ‑ scans.

Identify factors that affect the choice of diagnostic frequency.

Students should appreciate that attenuation and resolution are dependent on frequency.

Outline the basic principles of nuclear magnetic resonance (NMR) imaging.

Students need only give a simple qualitative description of the principle, including the use of a non-uniform magnetic field in conjunction with the large uniform field.

Describe examples of the use of lasers in clinical diagnosis and therapy.

Applications such as the use in pulse oximetry and in endoscopes should be discussed. Students should be familiar with the use of a laser as a scalpel and as a coagulator.

[|COMPUTED AXIAL TOMOGRAPHY] Explanation of the technique on Physics 2000 website [|FILM OF CAT SCAN THROUGH CADAVER] [|MRI APPLET] [|PHET SIMPLIFIED MRI]