John Seawright, B.S.
We’ve all seen it; the vicious collision that leaves a football wide receiver writhing in apparent pain; his strenuous, assisted walk to the locker room; and his eventual return to rejoin his team on the sideline with the accompanying statement from the sideline reporter, “The x-rays are negative.”
X-rays are a form of high energy, ionizing radiation with a wave frequency much smaller than visible light on the electromagnetic spectrum. A medically useful feature of an x-ray is its ability to deposit energy at altered rates through materials of different composition. This feature allows the imaging of dense structures inside the body, such as bones. The deposition of energy can also be used to damage and destroy tissue, making x-ray radiation a viable option to treat cancers. However, unfortunately x-rays do not differentiate between normal tissue and cancerous tissue, thus damaging healthy tissue, regardless of whether the application is for radiotherapy or diagnostic imaging. As ionizing radiation, e.g. x-rays, travels through tissue it will generate free radicals. These free radicals can diffuse through tissue and alter or damage cellular proteins and DNA, the genetic information of the cell. Exposure to and damage from ionizing radiation is frequently discussed as a promoter of cancer, but it is seldom mentioned that ionizing radiation exposure has also been associated with the development of cardiovascular diseases, like cardiomyopathy and atherosclerosis.
Many cardiovascular diseases involve endothelial dysfunction. This impairment of the endothelial lining of the blood vessels prevents proper dilation and blood flow. Endothelial dysfunction can be initiated by elevated levels of free radicals, which can either affect molecules involved with blood vessel dilation or damage the endothelial cell DNA and ultimately kill the endothelial cell. The more frequent the exposure to and/or the
higher the dose of ionizing radiation, the greater the risk for the development of radiation-induced cardiovascular diseases. The culture and mindset of today’s athlete encourages “playing through the pain” and returning to the game as soon as possible. A consequence of this mindset is immediate and frequent diagnostic imaging, which frequently exposes today’s athletes to ionizing radiation, and thus increasing their risk for cardiovascular disease. The incidence of Sudden Cardiac Death, largely due to cardiomyopathies and atherosclerosis, among young athletes is 2.5 times greater than in non-athletes. Medical irradiation represents the public’s largest source of manmade ionizing radiation exposure. The athlete population in particular, is at a greater risk for frequent radiation exposure, due to their higher propensity for injury from participating in competitive sports, than their non-athlete counterparts.
While the International Commission of Radiological Protection has set radiation dose limits for radiation workers, the dose limit for medical care patients is left up to the physician. It is therefore of greater importance for athletes and patients to understand the risks from diagnoses and treatments involving ionizing radiation, like radiography and computed tomography (CT) scans.
Further Reading:
- Cross TM, Smart RC, Thomson JEM. Exposure to Diagnostic Ionizing Radiation in Sports Medicine:Assessing and Monitoring the Risk. Clinical Journal of Sport Medicine. 2003;13(3):164-170. http://www.ncbi.nlm.nih.gov/pubmed/12792211
- Adams MJ, Hardenbergh PH, Constine LS, Lipshultz SE. Radiation-associated cardiovascular disease.Critical Reviews in Oncology/Hematology. 2003;45(1):55-75. http://ac.els-cdn.com/S104084280100227X/1-s2.0-S104084280100227X-main.pdf?_tid=a6589984-f652-11e3-ab90-00000aab0f6b&acdnat=1403032239_65b36f704b476260a0a9d8a825b1bd7d
- Montagnana M, Lippi G, Franchini M, Banfi G, Guidi GC. Sudden Cardiac Death in Young Athletes.Internal Medicine. 2008;47(15):1373-1378. https://www.jstage.jst.go.jp/article/internalmedicine/47/15/47_15_1373/_pdf