Chapter 2 – Principles of Radiation Biology and Radiation Protection
The International Commission on Radiological Protection (ICRP) and other organizations have worked diligently to investigate and educate scientific and regulatory agencies about the benefits and risks of ionizing radiation. The guidelines and recommendations created by the ICRP form the basis for radiological protection in Canada and most other developed countries. Exposure to ionizing radiation is monitored for healthcare workers and rules and regulations have been established that guide the use of protective clothing, shielding, and the safe acquisition of images for workers and patients. (4)
Facilities that administer radiation for diagnosis are regulated by provincial and federal agencies that oversee the safe and appropriate use of this diagnostic tool. These rules and regulations govern the assessment and maintenance of equipment, the radiation dose administered by this equipment, the monitoring of radiation exposure for patients and medical staff, and the proper protection of patients and staff from ionizing radiation.
The greatest exposure to radiation during an imaging procedure occurs at the source of the x-ray beam. Therefore, one should not stand in, or insert, any of their anatomy directly into the x-ray beam.
There is also radiation in the vicinity of the patient as a result of stray photons emitted by the x-ray tube or from radiation scattered during interaction with the patient’s anatomy. Increasing the distance from the source of the radiation will significantly reduce the quantity and the intensity of this in scattered radiation. The reduction in radiation intensity is related to the concept of the inverse square law i.e. the intensity of the radiation is inversely proportional to the square of the distance from the x-ray source. All medical staff must stand well back from the imaging equipment during exposures unless their direct attendance to the patient is required.
Personal protective equipment is very important. Barriers, shields, thyroid collars, aprons, leaded glass, leaded eyewear, etc. should be used in all situations where personnel may be exposed to radiation. Medical staff must wear protective lead garments to reduce their exposure to radiation.
Walls and doors of rooms that use radiation must be lined with lead. There must be appropriate signage identifying rooms or areas that deploy ionizing radiation. It is also required that warning lights are visible and lit when the x-ray machine behind the leaded door is emitting radiation to prevent inadvertent entry into the room without wearing radiation protection.
The annual exposure to radiation for medical staff must be monitored and reported. If staff exceed their annual limit for radiation exposure their duties must be adjusted to prevent any further exposure to radiation during the year.
If you are concerned about your exposure to radiation or how to protect yourself, you should contact the Head Medical Radiation Technologist of the medical facility you are working in or contact the local Radiation Safety and Protection Officer.