What Is Radiation?
Radiation is simply a type of energy; the most familiar form of radiation is visible light (like that produced from the sun or a light bulb). Other forms, like X-rays and gamma rays, are employed in a number of beneficial applications, including medicine. Natural radiation exposure comes from the earth (rocks, soil) and outer space (cosmic rays). A small amount of radioactive material even exists naturally in our bodies. Every year, each person is exposed to this natural radiation and a variety of other sources, including household smoke detectors and color television sets. Air travel increases exposure to cosmic radiation due to the higher altitudes (less atmospheric shielding).
Does Medical Imaging Save Lives?
Yes. Millions of Americans benefit each year from various radiological procedures used to diagnose and treat a wide variety of diseases. The use of radiation in these procedures — with low risks—offers a safe and cost-effective means to provide doctors with information that would otherwise require exploratory surgery, necessitate more costly and invasive procedures or simply be unavailable. The risks of not performing a needed medical exam are usually much greater than the risks of the radiation exposures associated with the exam.
As a Patient, What Do I Need To Know?
As with all medical procedures, the safety of radiological procedures is enhanced when patients are well informed about the particular test or treatment and there is a clear and open line of communication between patients and medical teams regarding safety and the treatment protocol. The value of diagnostic imaging is great and the risks are negligible compared to the health benefits of having the procedure.
The Radiation Risk from CT exams vs. the Beneficial Medical Uses of Radiation
CT scans account for approximately 4% of medical imaging exams. Unlike other medical imaging exams, such as conventional x-ray imaging, CT has the ability to image a combination of soft tissue, bone, and blood vessels. The exam can be very useful in providing diagnostic information on several areas of the body, including:
- the brain, vessels of the brain, eyes, inner ear, sinuses
- the neck, shoulders, cervical spine and blood vessels of the neck
- the chest, heart, aorta, lungs, mediastinum
- the thoracic and lumbar spine
- the upper abdomen, liver, kidney, spleen, pancreas and other abdominal vessels
- the pelvis and hips, male and female reproductive system, bladder, and GI tract
- the skeletal system including bones of the hands, feet, ankles, legs and arms, and jaws
In most cases, the benefits of finding disease with a CT scan outweigh the risks of x-ray radiation exposure and/or injections of imaging contrast and use of sedatives during the scan.
To balance image quality with any radiation safety concerns, radiologists use a protocol known as the ALARA principle, short for As Low as Reasonably Achievable. It’s meant to ensure that “CT dose factors are kept to a point where risk is minimized for maximum diagnostic benefit.”
There are times when performing a scan is very valuable and absolutely worth the risk. In the case of diagnosing acute appendicitis, for example, CT scans have become an almost indispensable tool, reducing the chances of removing a healthy appendix from 24 percent down to just 3 percent. Similarly, with life-threatening or potentially debilitating problems from head trauma, the obvious risks from radiation are outweighed by the benefit of the test.
Scientists have not yet determined whether low doses of radiation actually increase cancer risk or whether the risk rises only after exposure levels reach a certain threshold.
What about the radiation dose for CT scans?
There was an article published in the New England Journal of Medicine titled, “Computed Tomography — An Increasing Source of Radiation Exposure” to which the American College of Radiology (ACR) responded that it “may be inappropriate and cause patients to mistakenly avoid getting life-saving medical imaging care.”
The full ACR response to the article can be read here, in which the ACR expressed concern over the conclusions and comparisons made in the study. There continues to be similarly exaggerated “news” regarding the CT dose and its “link” to cancer.
Reducing the Amount of Radiation for CT Exams
Efforts are ongoing to protect patients from unnecessary radiation exposure from medical imaging procedures, including the Image Gently initiative for safety in pediatric radiology and an ACR-RSNA task force for adult radiation protection. In addition to following strict appropriate imaging utilization standards, radiologists and medical physicists stress the importance of minimizing dose without sacrificing diagnostic ability. Advances in CT technology over recent years have markedly decreased dose while maintaining optimal image quality.
It is important that radiologists and radiologic technologists subscribe to the principle of “As Low as Reasonably Achievable” (ALARA) or “As Low as Reasonably Possible” (ALARP). In essence, the ALARA/ALARP principle emphasizes using as little radiation as possible in order to achieve a needed diagnostic result. This can be accomplished by various means including controlling: how many x-ray exams are ordered, the type of x-ray exam ordered, how often the exam is performed, performing the exam as accurately as possible to avoid repeat x-rays, and using the lowest x-ray dose possible to achieve the needed diagnostic result.
In general, newer systems like the ones that are in use at Hillsborough Radiology, are more sensitive than older CT systems and may acquire a suitable image using a lower x-ray dose. CT scanner manufacturers continue to work with radiologists to create technology and protocols to acquire high quality CT images at the lowest possible dose.
Great effort has been made throughout radiology and the medical community to ensure patient safety while providing quality diagnostic images. It is important to realize that in a properly performed individual exam, the potential health benefits almost always outweigh the potential risks of radiation exposure. Simply put, patients should not hesitate having a study if it is medically indicated.
