By assuring quicker and more precise diagnosis and disease monitoring, diagnostic radiology has become essential to every specialty of medicine. According to some estimates, plain-film radiography, CT, fluoroscopy, and other modalities accelerate the
By assuring quicker and more precise diagnosis and disease monitoring, diagnostic radiology has become essential to every specialty of medicine. According to some estimates, plain-film radiography, CT, fluoroscopy, and other modalities accelerate the diagnosis of disease at least half of the time. Screening procedures such as mammography have proved they can save lives, and interventional techniques are attacking diseases in the heart, blood vessels, and liver.
But diagnostic procedures that deliver ionizing radiation carry a risk. Even low doses of ionizing radiation involve risks that cannot be eliminated entirely. Every person who undergoes an x-ray examination of the head and neck at a dose of 0.1 mSv has an added lifetime risk of developing cancer in the range of one in one million to one in 100,000. Every mammography exam or radiographic procedure in the abdomen and pelvis, hip, and spine at a dose of 1 mSv adds a cancer risk from one in 100,000 to one in 10,000. An intravenous pyelogram or barium enema carries a risk between one in 10,000 and one in 1000.
And entrance doses at the site of the body exposed to an x-ray beam vary widely from country to country. The International Commission on Radiological Protection (ICRP) has found that the difference between the lowest and highest doses in a radiology facility can fluctuate by a factor of about 100.
Although the risk level from a common radiographic examination increases the risk of cancer only a fraction, organizations such as the ICRP caution against exposing patients to ionizing radiation unnecessarily and suggest minimizing doses whenever possible. The ICRP believes that even small levels of risk can be reduced further by optimizing protection against unnecessary exposure to radiation.
RADIATION PROTECTION GUIDELINES
The ICRP has been formulating guidelines and recommendations on radiation protection since it was founded in 1928 by the International Society of Radiology. In 1999 and 2000, the organization released a series of four downloadable slide sets on its Web site (icrp.org) that deal with pregnancy and medical radiation, interventional radiology, CT dose management, and accidents in radiotherapy.
The ICRP also offers a download of its document Radiation and Your Patient: A Guide for Medical Practitioners, which advocates taking a number of steps to reduce the risk of radiation during diagnostic examinations. One sets a diagnostic reference level for every investigation to learn when a facility or a particular x-ray machine should be adjusted to reduce the average dose to patients.
The ICRP also recommends that certain diagnostic procedures should be avoided, including fluoroscopy and photofluorography for tuberculosis screening in children and adolescents. The group notes that fluoroscopy without electronic image intensification, which has been outlawed by developed countries because it delivers high doses to patients, should be abandoned in emerging nations as well.
RADIOGRAPHY SAFETY EDUCATION
Since the International Society of Radiographers and Radiological Technologists (ISRRT) held its first seminar on the use of ionizing radiation and radionuclides in Teheran, Iran, in 1971, the organization has stressed radiation safety and protection of patients in all its educational programs. It's not that schools of radiography throughout the world aren't well aware of international standards and local regulations for protecting patients against excessive exposure to radiation. It's just that radiography is no different from any other everyday activity-it's like driving a car.
"You know all the rules when you have to take your driving test, but I'm not sure that 10 years down the road, you're practicing all of them. The same thing happens in our field. People have to be reminded what they should be doing," said Shirley Hundvik, ISRRT director of education.
The ISRRT presents the fundamentals of patient dose evaluation and positioning, physical parameters of the equipment (mAs, kVp), calibration and operation of dosimetry and monitoring equipment, and overall QA and QC in meetings and workshops. It sponsors these meetings around the world because no place is immune from lapses in safety and radiation protection, Hundvik said.
"I can take you to places in the U.S. and Canada where safety is an issue," she said. "So we always deal with radiation safety and protection to improve the health system for the patient."