X-rays are a vital imaging tool used around the globe. Since first being used to image bones over 100 years ago, the X-ray has saved countless lives and helped in a range of important discoveries.
X-rays are a naturally occurring form of electromagnetic radiation. They are produced when charged particles of sufficient energy hit a material.
Over the years, scientists have shown concern over the health implications of X-rays. After all, they involve firing radiation at the patient. But, do its benefits outweigh its risks?
This MNT Knowledge Center article will discuss what X-rays are, how they are used in medical science, and the level of risk that they pose.
Fast facts on X-rays
Here are some key points about X-rays. More detail and supporting information is in the main article.
X-rays are a naturally occurring type of radiation.
They are classed as a carcinogen.
The benefits of X-rays far outweigh any potential negative outcomes.
CT scans give the largest dose of X-rays compared to other X-ray procedures.
In X-rays, bones show up white, and gasses appear black.
What are X-rays?
The first X-ray was carried out over 100 years ago.
Wilhelm Röntgen is credited with first describing X-rays. Just weeks after he discovered that they could help visualize bones, X-rays were being used in a medical setting.
The first person to receive an X-ray for medical purposes was young Eddie McCarthy of Hanover, who
fell while skating on the Connecticut River in 1896 and fractured his left wrist.
Everyone on the planet is exposed to a certain amount of radiation as they go about their daily lives. Radioactive material is found naturally in the air, soil, water, rocks, and vegetation. The greatest source of natural radiation for most people is radon.
Additionally, the Earth is constantly bombarded by cosmic radiation, which includes X-rays. These rays are not harmless but they are unavoidable, and the radiation is at such low levels that its effects are virtually unnoticed.
Pilots, cabin crew, and astronauts are at more risk of higher doses because of the increased exposure to cosmic rays at altitude.
There have, however, been few studies linking an airborne occupation to increased incidence of cancer.
To produce a standard X-ray image, the patient or part of their body is placed in front of an X-ray detector and illuminated by short X-ray pulses. Because bones are rich in calcium, which has a high atomic number, the X-rays are absorbed and appear white on the resulting image.
Any trapped gases, for instance, in the lungs, show up as dark patches because of their particularly low absorption rates.
Radiography: This is the most familiar type of X-ray imaging. It is used to image broken bones, teeth, and the chest. Radiography also uses the smallest amounts of radiation.
Fluoroscopy: The radiologist, or radiographer, can watch the X-ray of the patient moving in real-time and take snapshots. This type of X-ray might be used to watch the activity of the gut after a barium meal. Fluoroscopy uses more X-ray radiation than a standard X-ray, but the amounts are still extremely small.
Computed tomography (CT): The patient lies on a table and enters a ring-shaped scanner. A fan-shaped beam of X-rays passes through the patient onto a number of detectors. The patient moves slowly into the machine so that a series of “slices” can be taken to build up a 3D image. This procedure uses the highest dose of X-rays because a large number of images are taken in one sitting.