RADIOTHERAPY EQUIPMENT

Typical Number in Hospital: 3

Cost Bands: 6,7

References: 3

Ionizing radiation may be used as therapy since tumour cells are more susceptible to radiation damage than normal cells. The radiation used may be X-rays, beta-rays (electrons), gamma-rays, alpha particles, or neutron beams.

The effect is to displace electrons from atoms, thereby causing disruption of cell chemistry. The radiation dose which reaches the tumour depends upon the distance between the source and the skin, how well the radiation penetrates the tissues, and the quantity of radiation scattered into the treatment area from surrounding tissues. The depth of penetration of the radiation increases as the energy of the source increases and treatment is therefore provided for superficial tumours using low voltage X- rays (15-150 kV) and much higher energies (e.g.15 MeV) using an accelerator for deep-seated tumours.

Teletherapy apparatus produces radiation beams outside the body and directs them through the skin, varying the point of entry to the body to reduce the average dose at the skin if the area to be treated is deep within the body. Alternatively, sealed radioactive sources may be placed within body cavities to provide localized radiotherapy in a particular organ.

Radiotherapy is a complex subject, usually conducted in a special department employing doctors expert in cancer treatment, radiographers (therapy), physicists for treatment planning and dose calculations and technicians to manage the apparatus.