Applied Dosimetry (MDPH602)

COURSE MDPH602: 3 CREDITS

Prerequisites : MDPH601
Corequisites : None
Instructor : E.B. Podgorsak

The course deals with techniques, dosimetry, and equipment used for external and internal irradiation of patients with sealed radiation sources.


COURSE OUTLINE


1. The interaction of single beams of X and gamma rays with a scattering medium.

Percent depth dose. Scatter function. Peak-scatter-factor. Tissue-air-ratio. Scatter-air-ratio. Tissue-maximum-ratio. Tissue-phantom ratio. Equivalent squares and circles. Irregular fields. Beam modifying devices. Phantoms. Bolus materials.

2. Treatment planning with single photon beams.
Isodose distributions. Surface dose. Integral dose. Exit dose. Isodose distributions.Tissue inhomogeneities. Contour corrections.

3. Treatment planning for combinations of photon beams.
Opposing pairs. Combinations of opposing pairs. Angled fields and wedged pairs. Three-field technique. Rotational therapy. CT in treatment planning. Non- coplanar beams.

4. Radiotherapy with particle beams: electrons, pions, neutrons, heavy charged particles.
Isodose distributions and percentage depth dose. Advantages and disadvantages of particle beams.

5. Special techniques in radiotherapy.
Total and half-body irradiation with photon beams. Total skin electron irradiation. Electron arc therapy. Stereotaxy and radiosurgery. Rectal irradiation. Intensity- modulated radiotherapy.

6. Equipment for external beam radiotherapy.
Cobalt units. Orthovoltage and superficial x-ray units. Betatrons. Neutron generators. Simulators. Computerized treatment planning systems.

7. Medical linear accelerators.
Waveguide theory. Components of medical linear accelerators.

8. Relative dosimetry techniques.
Thimble ionization chamber. End-window ionization chamber. Thermoluminescent dosimetry. Radiation sensitive diodes. Radiographic film. Thermally activated currents. Radioelectrets.

9. Dosimetry in radiotherapy using small sealed sources.
Comparison of radium and radioisotope sources for brachytherapy. Source specification and calibration. Calculation of dose distribution in tissue around a sealed source. Sievert integral and more recent calculation algorithms.

10. Dosimetry of distributed radioisotope sources.
Absorbed dose per disintegration from internally administered radionuclides. Dosimetry of beta-type and gamma-type radiations. MIRD system. Integral dose from radioisotopes. Permissible doses and concentrations.

11. Dosimetry in radiobiology and radiation protection.
Dose equivalent. Patient dose (entrance and organ doses) in diagnostic radiology and nuclear medicine. Irradiation of experimental specimens and animals.