Collimation Radiation Safety

Radiation therapy, or the use of ionizing radiation such as x-rays or gamma rays to kill cancer cells, is one of the most common treatments for cancer. In recent years an advanced technique called intensity-modulated radiation therapy(IMRT) has become increasingly popular. IMRT relies on sophisticated technology to maximize dosage to the tumor while minimizing damage to surrounding tissues. Proper safeguards are vital, however, because of the danger high-dose radiation poses to human health and safety.

Collimation and IMRT

• A collimator is a device that helps to shape and narrow a beam of radiation. Multileaf collimators use individual "leaves" of a heavy metal like tungsten to block parts of the x-ray beam and control the amount of radiation delivered to the patient at each point. The process is typically computer-controlled; complex software algorithms determine how to shape the beam of radiation based on a treatment plan designed by an oncologist and a medical physicist.

Benefits

• Since IMRT is more precise and delivers less radiation to surrounding tissue, the chance of serious side effects is typically reduced. Moreover, doctors are able to treat tumors with radiation that might hitherto have been accessible because the impact on surrounding tissue would have been too great. IMRT is used for cancers of the head and neck, prostate cancer, central nervous system cancers and various other types of cancer.

Accidents

• While mistakes are rare, there are several possible sources of error that have caused accidents in the past. A high-profile January 2010 series in the New York Times documented a number of cases where deaths or serious injuries had occurred owing to either human or computer error; patients were improperly administered the wrong dose of radiation by the computer-controlled system. When they do occur, these kinds of incidents are often fatal or severely harmful because of the dangerous nature of ionizing radiation.

Safety Precautions

• It's essential that hospital or facility staff be properly trained on how to operate the computer software and equipment. Hospital physicians should also run tests or trial runs using a "phantom patient" to make sure the machine is delivering the correct dose of radiation prescribed by the treatment plan. As noted in the New York Times series, accidents typically occurred through a combination of human and computer error--when the computer software crashed, for example, and hospital staff did not catch the error.

Considerations

• In general IMRT/multileaf collimators are actually safer than past radiation therapy techniques because surrounding tissue exposure is minimized; consequently, they are a powerful tool to treat cancer and can often achieve highly successful results. While accidents are rare, however, they have happened in the past, so it's important that hospital physicians and staff be trained on proper procedure when working with IMRT.