An x–ray is a generally painless test that creates an image of part of the body by using low doses of electromagnetic radiation that are reflected on film or fluorescent screens. Standard or specialized x–rays can be used in diagnosis of a wide range of painful conditions, including:
Bone chips and fractures
Jaw or dental pain
Osteoporosis
Herniated discs and degenerative disc disease
Benign prostatic hyperplasia
In addition, x–rays are used in diagnosing nonspecific causes of pain (e.g., back pain, joint pain). However, x–ray examinations have limitations and explain only a relatively small number of the pain complaints that physicians receive. X–ray tests alone are often unable to diagnose a pain source. They are used most effectively for pain diagnosis when they are combined with other tests (e.g., physical exam, MRI) and correlated with specific symptoms.
X–ray tests do not typically cause any side effects when administered correctly. A lead apron is often worn to protect organs from radiation damage. Although they pose very little risk, x–rays may be harmful to developing fetuses. Therefore, women who are or may be pregnant should inform their physician or x–ray technologist of their condition.
Some modern tests (e.g., CAT scan) use computers along with x–rays to create three–dimensional imaging. X–ray tests are often viewed by an x–ray specialist (radiologist) before the results are explained to the patient.
Special requirements may be necessary prior to administering some specialized x–rays. Certain x–ray tests, such as barium enema, require a contrast medium (dye) to be injected, swallowed or inserted. This helps outline certain internal structures on x–ray film. X–ray tests requiring a contrast medium can take as long as an hour. However, most standard x–rays take only a few seconds or minutes.
About x–rays
An x–ray is a test in which part of the body is imaged by using low doses of electromagnetic radiation that are reflected on film or fluorescent screens. These images, also known as radiographs or roentgenograms, are used to diagnose and monitor the treatment of various diseases.
X–ray tests are fast and relatively inexpensive. They are usually noninvasive and painless but are sometimes minimally invasive, meaning they may involve injection with a contrast medium (dye) to help highlight internal structures. They are generally safe for people of all ages when used correctly. Medical professionals often perform x–ray exams in the diagnosis of many painful conditions, including:
Detecting fractures and other trauma to bones
Assessing sprains and strains
Locating or checking causes of dental pain
Screening for osteoporosis
In addition, x–rays are sometimes used to diagnose nonspecific sources of pain, such as:
Back pain
Joint pain (e.g., knee or wrist)
Internal problems (e.g., abdominal pain)
Head or brain injury
Chest pain
Motor, bowel, bladder or sexual problems
Progressive conditions, such as advanced arthritis
Examinations with x–ray tests explain only a small percentage of the nonspecific pain complaints physicians receive. X–ray results are two dimensional, with the boundaries between internal structures often blurred on x–ray film. X–rays may be useful in determining irregularities in the body but cannot image pain itself. Consequently, results may be misleading or inconclusive in some instances. They are used most effectively for pain diagnosis when they are combined with other assessments (e.g., physical exam) and correlated with specific symptoms.
Other medical tests that combine computer and x–ray technology (e.g., fluoroscopy, CAT scan) may also be used to confirm the source of some types of pain (e.g., back pain, tooth pain). In some cases, a series of x–ray tests over a period of time may also be needed to assess a condition or compare changes.
In addition to their diagnostic roles, x-rays are used at much higher intensity in radiation therapy for cancer.
How x rays work
X–ray tests work by passing small amounts of electromagnetic radiation through the body to produce images of bones, teeth and internal organs. The type of x–ray test administered depends on which part of the body needs to be examined.
The x–ray is the oldest imaging technology still in use today. It was discovered almost by accident in the 1890s by a German scientist named Wilhelm Conrad Roentgen. Because no one understood the rays that were at work in forming these images, the rays were initially called x–rays. Much more is now known about this form of radiation.
Bones and cartilage tend to be dense and absorb x–rays better than do soft tissues (e.g., skin, fat, internal organs). As a result, bones appear white on x–rays whereas tissues often are gray. Organs or structures containing mostly air, such as the lungs, appear black. Generally, the denser the bone or organ, the more clearly it will show up with an x–ray. The results may first be viewed by a physician with special training in interpreting x–ray results (radiologist) before they are explained to the patient.
An x–ray machine produces a beam of radiation that is pointed by a tube at the part of the body being examined. The area to be examined is placed between the metal film cassette and the x–ray tube, which is surrounded in lead casing except for a small opening through which the rays are beamed. Within the x–ray tube, a beam of electrons is fired into a target made of a metallic element known as tungsten, emitting photons that travel straight and outward from a point on the target to the area being x–rayed. The resulting images are recorded on either film or a fluorescent screen.
The energy contained in the photons may cause some cell damage. Most of this cell damage is repaired quickly, but some may be permanent. Considering the low doses of radiation in modern x–ray tests, most physicians believe the benefits of x–rays outweigh the very small risk associated with them. However, young children and developing fetuses are more sensitive to radiation. Women should advise their physician if they are pregnant before getting an x–ray.
Additional techniques may be necessary to get a clear view of soft tissues, hollow areas or fluid–filled body parts. For example, a physician may administer a special dye known as a contrast medium to produce sharper contrasts in light and dark areas on the x–ray. These contrasts give the physician a clearer image of areas such as the urinary tract, the spinal cord, blood vessels and the gallbladder.
Types and differences of x–rays
In some cases, standard x–ray tests are not enough for diagnosis of the pain source. In these instances, there are a number of specialized x–ray tests available, including:
CAT scan (computed axial tomography). This noninvasive or minimally invasive test uses multiple x–ray images, taken from different angles, to create three–dimensional images of body structures. It may be performed alone or with the use of a special dye called a contrast medium. This test may be used when an area inside the body needs to be viewed from multiple angles and in greater detail.
Arthrography. This minimally invasive test involves injection of a contrast medium into a joint, followed by a standard x-ray, CAT scan or MRI (magnetic resonance imaging). Its uses include identification of tendon and ligament injuries, torn rotator cuff and loosening of joint replacements or other prostheses.
Discography. This test is often performed on patients who are considering back surgery or who have not responded well to conventional treatments for back pain caused by conditions such as degenerative disc disease or a herniated disc. The patient wears a metal–free hospital gown and lies on an imaging table. After the skin is numbed with anesthetic, a needle is inserted into the intervertebral disc using x–rays as guidance. Once in place, the needle injects contrast dye to outline any damaged areas and CAT scans are taken. Pain medicines may be administered if pain persists beyond the usual recovery time, typically about one hour.
Fluoroscopy. This type of test uses x–rays to image internal body organs while they are in motion. A continuous x–ray beam is focused on the part of the patient being examined to create a detailed, moving image that appears on a monitor, much like a movie. Fluoroscopy can be used in pain management - for example, to guide corticosteroid injections inside a joint.
DEXA scan (dual-energy x-ray absorptiometry). Also known as a bone density scan, DEXA is the standard method of measuring bone mineral density. DEXA scans are often used to screen for the bone-thinning disease osteoporosis, especially in women after menopause. Some DEXA units use ultrasound instead of x-rays.
Angiography. This is an x–ray procedure in which contrast material is injected into one of the arteries of the heart. This allows the physician to detect if there is obstruction in coronary arteries. Angiography may be performed if the patient is experiencing chest pain.
Barium x-rays. These imaging tests use a chalky element called barium as the contrast medium. They include:
Upper GI (gastrointestinal) barium tests, such as barium swallow, barium meal and small-bowel series. Fluoroscopy or other x-ray techniques are performed after the patient consumes a liquid or solid containing barium. These tests can be used in diagnosing conditions that cause esophageal or abdominal pain, such as gastroparesis (delayed emptying of the stomach).
Barium enema. The patient is given an enema with a solution containing barium. The barium coats the insides of the intestines, allowing this area to be viewed in greater detail with an x–ray. This test may be used to determine causes of intestinal or pelvic pain, such as colon cancer.
Intravenous pyelography (IVP). These x-rays of the urinary tract use a contrast medium to help detect conditions such as kidney stones, bladder cancer and prostate enlargement (benign prostatic hyperplasia).
Mammography. Mammograms are specialized x-rays that create detailed images of the breasts. They are used to screen for and diagnose breast cancer and other breast conditions, such as cysts. The American Cancer Society recommends that women have annual mammograms starting at age 40.
Before the x–ray test
X–rays may be taken in a laboratory, physician’s office or hospital. In general, no special preparation is needed before an x–ray is taken, unless a special dye called a contrast medium is going to be used. Contrast mediums outline a specific body area internally. They can be swallowed, injected into a vein or inserted rectally, and have a dull, opaque appearance on film.
If a contrast medium will be used, patients may be asked not to eat or drink after midnight before the test, and the physician may make minor changes in how the patient takes medication. The physician will ask about the patient’s history of allergies to screen for a potential allergic reaction to the dye.
A radiology technician or specially trained nurse generally takes x–ray films. At the time of the test, the examiner will ask the patient to remove any objects that may show up on the image (e.g., clothing, jewelry, wigs, watches or dentures). Splints or prosthetic limbs may also be removed in some cases.
Patients should inform the examiner if they have had an x–ray using a contrast dye or barium in the past few days. They should also make sure the examiner is aware of all medications that have been taken recently, including over–the–counter medications.
Female patients should be sure to inform the examiner if they are or may be pregnant because x–rays can be harmful to fetuses in rare cases. In cases where the benefits of the x–ray outweigh the potential risks, pregnant women may wear a lead apron over their abdomen during the test.
A lead apron is also often worn by patients to help protect sex organs from x–rays. In high doses, women’s eggs and men’s sperm can be affected by radiation. However, the risk of this occurring as a result of an x–ray test is extremely low. Women should also inform the examiner if they have an IUD (a form of birth control) implanted.
During and after the x–ray test
X–ray tests are performed by most physicians and dentists for a variety of conditions and diseases. Depending on the procedure, the patient will sit, stand or lie down between the x–ray machine and x–ray film. Pillows or soft weights may be used to hold the patient in position if necessary. Momentary compression of the body area being examined is occasionally needed for some x–ray tests.
The x–ray machine is then pointed at the area being examined. While exposed to x–rays, the patient may be encouraged to hold their breath to help remain still. Movement during an x–ray test can cause images to blur on film. Multiple x–rays may be taken from different angles if necessary. In the case of dental x–rays, a small piece of film is usually placed in the mouth behind the teeth being tested. The patient bites down on attached paper to hold the film in place before the x–ray is taken.
X–ray tests can be as short as a few seconds (e.g., dental x–rays) or minutes (e.g., bone x–ray), or take as long as an hour in cases where a contrast medium has been administered (e.g., barium enema). Occasional swelling, pain or redness may be experienced at the injection site if a contrast medium is administered this way.
The x–ray film is usually developed within a few minutes. A physician who specializes in interpreting x–rays (radiologist) may first view the results before they are explained to the patient. Additional x–rays may be taken from different angles if necessary.
Patients can resume normal activities immediately following the x–ray(s). The radiologist or the patient’s physician will interpret the findings and review them with the patient either that same day or at a follow–up visit. Additional tests (e.g., MRI, radionuclide imaging, arthroscopy) may be necessary if the x–rays do not provide enough information on the tissues or structures being studied) may be necessary if the x–rays do not provide enough information on the tissues or structures being studied.
Potential risks and benefits with x–rays
The levels of radiation used in x–ray procedures are so low that they pose only minimal risk to patients. As a precaution, some patients may be asked to wear a lead apron to shield sex organs from exposure to radiation. At very high doses, radiation can damage a woman’s eggs or a man’s sperm.
High doses of radiation can also be harmful to a developing fetus. Therefore, women who are or may be pregnant should be sure to inform their physician or x–ray technologist of their condition. It may be necessary to take certain precautions to protect the fetus.
Precautions that can be taken in an x–ray procedure include:
Ask the physician how an x–ray will help. Patients have a right to understand why a physician believes an x–ray is necessary. If it is medically necessary, it should not be refused, as the small risk of radiation is much lower than the risk of not having a condition properly diagnosed. Patients should not insist on having an x–ray if it is not medically necessary.
Ask for gonad shields for x–rays of the lower back, abdomen or area near the sex organs. These lead shields can protect a man’s testicles or a woman’s ovaries from radiation, which protects reproductive cells. This shield should be considered for any patient who may have children in the future. In some cases – such as in x–rays of the gonads – these shields are not an option.
Keep track of x–rays with an x–ray record card. Patients who have x–rays taken should record the date, type of exam and where the x–ray is kept. In some cases, these old x–rays can be used instead of taking new x–rays. Each family member should have an x–ray card.
Some x–ray procedures require the patient to swallow a contrast medium. In rare cases, patients experience an allergic reaction to this dye. Patients with a history of such reactions should inform their physician or x–ray technologist.
Questions for your doctor
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about x–rays:
What type of x-ray is recommended for me?
How long will this particular x–ray test take?
Will this x–ray test require the use of a contrast medium?
Does it require any preparation on my part?
I think I’m pregnant. Should I wait to have an x–ray?
How much radiation will be used for this particular x–ray test?
What is the margin of error for x–ray tests in detecting diseases, broken bones, etc.?
Will I receive other tests in addition to the x–ray test?
I recently had an x–ray. Am I at risk for being exposed to too much radiation if I have another?
When is it safe for my child to have an x–ray test?
