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| Typical Number in Hospital: 3 | Cost Bands: 6,7 | References: 3 |
This is a cancer treatment machine employing high-energy electromagnetic radiation delivered from a point outside the body as opposed to sealed sources of radioactive material implanted within the body.
Machines for teletherapy include high-voltage X-ray machines, linear accelerators, high-energy isotope units and neutron generators. X-ray units for teletherapy include superficial X-ray generators (50-150 kV), orthovoltage units (150-500 kV), linear accelerators to produce electron or X-ray energies between 4 and 15 MeV, and isotope units which may produce 0.66 MeV (caesium-137) or 1.17 MeV and 1.33 MeV for cobalt-60 sources.
In the case of teleisotope units the rays cannot be directed and so they are restricted by a lead collimator. The primary collimator in the treatment head confines the beam to a broad cone covering the maximum possible area to be irradiated, and a secondary collimator or applicator further restricts this for the particular treatment regime required. If this is an applicator it is placed on the skin of the patient, thus defining the source-to-skin distance (SSD).
Content and Design Copyright 2000 Dr. Malcolm C Brown. See Title Page for more details