Radiation Therapy

Radiation Therapy or Radiation Oncology is a true-targeted therapy with treatment directed precisely at the site of the cancer. It may be used as part of a larger treatment strategy that includes a systemic therapy – either chemotherapy or hormonally-based therapy – or it may be administered alone. The science behind radiation oncology continues to make rapid advances in scope and technique, thus reducing side effects and sparing healthy tissues by targeting the disease more precisely.

• External Beam Radiation employs highly focused beams of energy that are directed at the cancer cells from outside the body. The planning and delivery of these beams are built upon a three-dimensional model of the individual patient, created from CT and MR scans of the patient. This 3-dimensional conformal planning uses these scans to show the exact location of the cancerous cells and the normal nearby organs, so that the safest delivery route can be determined.
• IMRT, or Intensity Modulated Radiation Therapy, is a particular type of 3D conformal radiation delivery that is well-suited to colorectal cancer treatment. Using this sophisticated technique, each of the beams is modified to reduce the risk of injury to nearby organs while delivering higher doses to the tumor itself.
• IGRT, or Image Guided Radiation Therapy, is a further improvement in IMRT that takes into account the fact the target and normal tissues may actually move during the time that treatment is being delivered. By using special imaging techniques, such as the placement of fiducial seeds in the tumor, or CT scans obtained immediately before each treatment, slight modifications in the setup can be made instantly that will improve the safety of the treatment by taking these motions into account.
• RapidArc™ Radiotherapy Technology is a technology that allows for daily IGRT treatment of the tumor in a matter of 2-3 minutes, thereby reducing the time which motion can occur.
• TomoTherapy® is a technology for IMRT delivery that divides a single radiation beam into many smaller, narrow “beamlets” that precisely conform to the tumors and minimize damage to surrounding healthy tissues.
• Brachytherapy is the placement of radioactive substances into direct contact with the target organ, thereby reducing the dose of radiation to nearby structures. These techniques require some surgical techniques. High Dose Rate (HDR) Brachytherapy uses temporary implants which are placed in a number of hollow tubes through the skin into the tumor site. A single radioactive seed is then temporarily routed through these tubes on multiple occasions to deliver the radiation dose before removing the tubes.

To select a radiation oncologist who treats colorectal cancer, visit our Colorectal Cancer Specialists web page.

Reviewed 01/2011