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. 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.
Radioactive material is found naturally in the air, soil, water, rocks, and vegetation. 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. 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.
Computed tomography (CT): The patient lies on a table and enters a ring-shaped scanner. The patient moves slowly into the machine so that a series of “slices” can be taken to build up a 3D image.
For this reason, X-rays are classified as a carcinogen by both the World Health Organization (WHO) and the United States government. Each procedure has a different associated risk that depends on the type of X-ray and the part of the body being imaged.
However, X-rays provide such a low dose of radiation that they are not believed to cause any immediate health problems. The fact that X-rays have been used in medicine for such a significant length of time shows how beneficial they are considered to be.
Although an X-ray alone is not always sufficient to diagnose a disease or condition, they are an essential part of the diagnostic process. Non-invasive: An X-ray can help diagnose a medical issue or monitor treatment progression without the need to physically enter and examine a patient.
They can also help in the treatment of tumors and remove blood clots or other similar blockages Unexpected finds: An X-ray can sometimes show up a feature or pathology that is different from the initial reason for the imaging. For instance, infections in the bone, gas or fluid in areas where there should be none, or some types of tumor.
A recent report on the matter, published in the American Journal of Clinical Oncology, claims that X-ray procedures carry no risk. The paper argues that the type of radiation experienced in a scan is not enough to cause long-lasting damage.
The authors claim that any damage caused by low-dose radiation is repaired by the body, leaving no lasting mutations. CT scans in children may triple the risk of brain cancer and leukemia, especially when administered to the abdomen and chest at certain doses.
The authors go on to point out that despite being bombarded by cosmic rays and background radiation, the people of America are living longer than ever, partly because of advancements in medical imaging, such as the CT scan. Every six months like clockwork, Melissa O’Brien, a freelance writer in Kennesaw, Georgia, takes her two children, Alexandra and Evan, to the dentist for a cleaning.
It’s impossible to tell, because there are no good studies showing the right number of X-rays to give someone who isn’t having any particular dental problem. While some dentists do bite wing X-rays every six months on a healthy patient, others hardly ever do them, relying instead on a visual examination of the mouth with a sharp explorer and a mirror.
It’s an important question, since dental X-rays are the only form of medical radiation received on a regular basis by large numbers of American men, women, and children. “It’s crazy,” says Dr. Nicholas Hello Russo, an instructor in the department of oral and maxillofacial surgery at the Harvard University School of Dental Medicine.
“We’re doing an experiment on a vast number of people in this country, and we have no idea how it will play out in the next 15 or 20 years.” Four bite wing X-rays, which is what many people get in a routine exam, give about .005 millisieverts of radiation, according to the American College of Radiology.
But many dentists say too many of their colleagues aren’t following them, and are giving X-rays far too frequently, exposing patients to unnecessary radiation, not to mention increasing health care costs. “Bite wings cost about $50 or $60, and a lot of dental insurance plans pay for them once a year,” he says.
They’re so proud to have it, and in the back of my mind I’m thinking, am I paying for this machine every time you ask for an X-ray?” But if you have a healthy mouth and aren’t at high risk for decay, you don’t necessarily need X-rays every year.
Stuart White, a professor emeritus at the UCLA School of Dentistry, says the key is that each patient should be assessed by the dentist before getting an X-ray. “I would be wary of situations where the dental assistant makes the X-rays before the dentist has seen the patient,” he says.
“Be wary also of an answer along the lines of ‘We make bite wings on everybody every six months,’” White says. Sometimes it’s a part of the lead apron that covers your chest, and other times it’s a separate piece.
“When I take my grandchildren to the dentist, and they’re getting X-rays and there’s no thyroid collar, I’m jumping up and down and saying ‘Stop!’” Matheson says. In that process, unstable nuclei may emit a quantity of energy, and this spontaneous emission is what we call radiation.
As previously indicated, matter gives off energy (radiation) in two basic physical forms. Essentially, a half-life of a radioactive material is the time it takes one-half of the atoms of a radioisotope to decay by emitting radiation.
In some elements, the nucleus can split as a result of absorbing an additional neutron, through a process called nuclear fission. When a nucleus fission, it causes three important events that result in the release of energy.
Non-ionizing radiation includes visible light, heat, radar, microwaves, and radio waves. Consequently, when ionizing radiation passes through material, it deposits enough energy to break molecular bonds and displace (or remove) electrons from atoms.
This electron displacement creates two electrically charged particles (ions), which may cause changes in living cells of plants, animals, and people. For example, we use ionizing radiation in smoke detectors and to treat cancer or sterilize medical equipment.
These alpha emitters are primarily used (in very small amounts) in items such as smoke detectors. In other words, these particles of ionizing radiation can be blocked by a sheet of paper, skin, or even a few inches of air.
Beta particles, which are similar to electrons, are emitted from naturally occurring materials (such as strontium-90). Such beta emitters are used in medical applications, such as treating eye disease.
Nonetheless, a thin sheet of metal or plastic or a block of wood can stop beta particles. Similarly, x-rays are typically used to provide static images of body parts (such as teeth and bones), and are also used in industry to find defects in welds.
Several feet of concrete or a few inches of dense material (such as lead) are able to block these types of radiation. Of the five types of ionizing radiation discussed here, neutrons are the only one that can make objects radioactive.
This process, called neutron activation, produces many of the radioactive sources that are used in medical, academic, and industrial applications (including oil exploration). Fortunately, however, neutron radiation primarily occurs inside a nuclear reactor, where many feet of water provide effective shielding.
DISCOVERY OF X-RAYS were first observed and documented in 1895 by German scientist Wilhelm Conrad Roentgen. He discovered that firing streams of x-rays through arms and hands created detailed images of the bones inside.
To study the corona, scientists use data collected by x-ray detectors on satellites in orbit around the Earth. Japan's Hi node spacecraft produced these x-ray images of the Sun that allow scientists to see and record the energy flows within the corona.
Due to the high energy and penetrating nature of x-rays, x-rays would not be reflected if they hit the mirror head on (much the same way that bullets slam into a wall). NASA's Mars Exploration Rover, Spirit, used x-rays to detect the spectral signatures of zinc and nickel in Martian rocks.
The x-ray data reveal hot gases at about ten million degrees Celsius that were created when ejected material from the supernova smashed into surrounding gas and dust at speeds of about ten million miles per hour. By comparing infrared and x-ray images, astronomers are learning more about how relatively cool dust grains can coexist within the super-hot, x-ray producing gas.
These high-energy particles can be swept up by Earth's magnetosphere, creating geomagnetic storms that sometimes result in an aurora. The energetic charged particles from the Sun that cause an aurora also energize electrons in the Earth's magnetosphere.