Text b. Radiation treatment planning

Radiation treatment planning is designed to ensure that the radiation therapy will have maximum benefits with minimal potential risk. This involves working out an exact site, angle of radiation, dose, and so on.

For example, in radiation therapy planning for breast cancer, patients undergo simulation sessions during which a tumour is scanned and analyzed, and marks are made on the skin with ink or tattoo - all contributing to the best delivery of the real therapy later on.

Radiation planning can be a detailed process involving a number of health care workers, including doctors (oncologists and specialist radiologists), nurses, radiographers and other technicians.

Just as side effects depend on the individual patient's circumstances, so to do the exact form of radiation therapy and the planning for it. The planning will:

• Reflect the type, position and size of the cancer, and whether the tumour is close to radiation-sensitive tissues or organs

• Take into account the depth to which the radiation will need to penetrate to reach the target, and consider the patient's general health and clinical history.

• Usually involve CT scanning, but sometimes make of less sophisticated X-ray imaging, or MRI and PET scans.

• Occasionally involve the use of contrast mediums or other markers that help to define tumours, and inks or tattoos and molds or masks that help to pinpoint the radiation target.

Modern radiation planning is usually computer-assisted and sophisticated and powerful enough to produce 3D images of tumours.