MEDICAL PHYSICS

Syllabus: Topic 3D

 

Edexcel Physics GCE syllabus: Topic 3C

D1 Nuclear medicine

  1. Radioisotopes for nuclear medicine; metastable radionuclides. Production by neutron irradiation and elution methods: in particular 123I, 131I and 99mTc.
  2. Radionuclides as tracers. Dilution studies; measurement of body fluids. Uptake studies; use of model or ‘phantom’. Imaging body parts.
  3. Physiological effects of radiation. Range and effects of alpha, beta and gamma radiation. Destruction and mutation of cells.
  4. Radioactive and biological half-lives; effective half-lives. Basic principles of radiological protection. 1/te = 1/tr + 1/tb
  5. Gamma camera. Principles of collimator, scintillation counter and photomultiplier.
  6. Use of gamma radiation for therapy. 60Co sources for destruction of tissue.
  7. Energy of radioactive emissions. keV and MeV as measures of the energy of emitted radiations.

D2 X-rays and ultrasonics

  1. X-ray production. The rotating anode X-ray tube. Energy of accelerated electrons in eV. Efficiency. (Photons and a knowledge of E = hf are not required.)
  2. MeV X-rays for therapy. Absorption not strongly dependent on proton number. Multiple beams and rotational treatment. Alignment devices. Criticality of dose.
  3. keV X-rays for diagnosis. Absorption strongly dependent on proton number. Detection with photographic plates. Radiographs of bones, tissues and air spaces.
  4. X-ray geometry. Point source, shadows, use of a lead anti-scatter grid. Inverse square law.
  5. Ultrasonics in medicine. The sonar principle. Knowledge of c = expected: small wavelengths give rise to better resolution.
  6. Scanning methods for ultrasonic diagnosis. Basic principles only. A-scans and B-scans.
  7. Reflection and absorption. Acoustic impedance Z. Dependence of Z on speed of wave and density of medium; Z = cρ; Reflection coefficient = (Z1 Z2)2/(Z1 + Z2)2; The need for a coupling medium.
  8. Comparison of ultrasonic and X-ray techniques in diagnosis. Health and safety aspects of the use of ultrasound and X-rays.


Further reading: an informative book is 'Medical Physics' by Martin Hollins

 

stuff to be included in medical physics web pages