Radiation therapy

Radiation therapy (or radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to control malignant cells (not to be confused with radiology, the use of radiation in medical imaging and diagnosis). Although radiotherapy is often used as part of curative therapy, it is occasionally used as a palliative treatment, where cure is not possible and the aim is for symptomatic relief. Other rare uses are to wipe out the immune system prior to transplant to reduce the incidence of tissue rejection, called total body irradiation (TBI); to calm hyperactive muscles—such as might cause twitchy eyes—with mild superficial treatments; and to form scar tissue around a stent to reinforce the vascular wall.

Image Guided Radiation Therapy

Image Guided Radiation Therapy (IGRT) machines have a CT scanner integrated with the treatment system, or an X-Ray Tube and aSi-detector mounted on the gantry of the linear accelerator. The patient can be scanned and the tumour located in 3D space immediately before treatment. The ability to correct for movement and setup errors allows smaller margins to be used, sparing healthy tissue and escalating the tumour dose. First systems using ultrasound for guidance are on the market. Using ultrasound instead of CT has the advantages of a higher soft tissue contrast, no additional ionizing radiation and cost efficient application.

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