Martin E. Liebling, M.D., FACP
An x-ray is a painless test in which an image of part of the body is created by using low doses of electromagnetic radiation and recorded on film or fluorescent screens. X-rays can be used to diagnose a wide range of conditions, from bronchitis to a broken arm. Depending upon a physician’s evaluation of an x-ray image, further tests may be ordered.
X-rays are often used to help detect and diagnose cancers in the body, including those of the lungs, intestines, stomach, kidneys and breasts. An X-ray may detect a tumor in an organ such as the lung, and can indicate if the cancer has spread (metastasized) to other parts of the body.
X-ray images typically are taken with no preparation, but in some cases, the physician might use a special dye called a contrast medium. This dye appears on the x-ray image and is helpful in highlighting certain structures and conditions within the body. If contrast medium is going to be used in an x-ray, the patient may need to alter his or her diet or medication schedule. Women who are pregnant or who might be pregnant are urged to either avoid x-rays or to wear a protective lead apron over their abdominal area.
About x-rays & cancer
An x-ray is a painless test in which an image of part of the body is created by using low doses of radiation and recorded on film or fluorescent screens. These images, also known as a radiograph or roentgenogram, are used to diagnose and monitor the treatment of various diseases. They are noninvasive, relatively inexpensive and fast.
Standard x-rays can be used to detect many types of cancer. For example, x-rays of the chest are frequently used to check for lung tumors that have either started in the lungs or spread to the lungs from elsewhere in the body. In other cases, x-rays might help distinguish the nature of a disease. For example, an x-ray can help determine whether an individual’s sinus problems are related to an infection or a more serious condition.
Radiologists (physicians who specialize in reading x-rays) and other healthcare professionals can use the details gleaned from x-rays to identify cancerous growths. For example, bone cancer may be suspected when the bone appears to be ragged rather than solid. In other cases, the cancer may appear as a hole in the bone or a mass that extends to other tissues.
In some cases, standard x-ray procedures may not be sensitive enough to detect very small abnormalities or tumors hidden in the body by other organs. In such situations, an x-ray procedure known as a CAT scan (computed axial tomography) may be helpful. Instead of taking a single x-ray image, a CAT scanner rotates around the body to capture multiple images. A computer combines these images into detailed “slices” of a person’s internal body structure.
X-ray technology is often used to treat cancer and other conditions that involve rapid and harmful tissue growth. High doses of radiation are meticulously calculated and aimed to destroy cancer cells and tumors in various parts of the body while sparing the healthy normal cells. This is known as radiation therapy and is not considered an x-ray.
How x-rays work
Imagine that an individual is standing between a wall and a window through which sunlight is streaming. Because sunlight cannot pass through the solid barrier created by the body, it will cast a shadow against the wall. X-rays have been likened to rays of sunlight because they cannot pass through solid barriers such as bones, organs or tumors. As a result, these barriers will appear on the special x-ray film in white, whereas less dense barriers, such as organs, muscle and fat, will appear in varying shades of grey. Bones, which are dense and calcium-rich, will appear the whitest of all internal structures. Any solid objects, such as metal, will appear as bright white.
Additional techniques may be necessary to get a clear view of softer 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.
X-rays were 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 imaging.
Today, the special silver-coated x-ray film is contained in a flat cassette that is placed on the far side of the patient. The area to be examined is placed between the metal film cassette and the x-ray tube. This tube 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 chemical element known as tungsten, emitting photons that travel straight and outward from a point on the target to the area being x-rayed.
X-ray images can be recorded on either film or a fluorescent screen. Increasingly, digital x-ray technology detects and transmits the image to a computer’s memory and can produce it in some digital media. Such technology involves lower radiation doses and instant images with instant accessibility.
Some of these photons pass directly through the body, while tissues in the body absorb the rest. The energy contained in the photons may cause some cell damage. Most of this cell damage is repaired quickly, but some may be permanent and exposure to x-ray doses is cumulative. Considering the low doses of radiation in modern x-ray tests, most physicians feel the benefits of x-rays outweigh the very small risk associated with them. However, young children, including developing fetuses, are more sensitive, and women should advise their physicians if they are pregnant or think they might be pregnant.
Before the x-ray test
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. X-rays may be taken in a laboratory, physician’s office or hospital. If a dye will be used, then 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 his or her medication. The physician will also 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, he or she will ask the patient to remove any objects that may block or blur the image (e.g., clothing, jewelry, wigs, watches and/or dentures). Patients should inform the examiner if they have had an x-ray using a contrast dye or barium in the past few days. Patients 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, or if they currently have an IUD (a form of birth control) implanted. Although today’s modern equipment and technology uses only minimal radiation when taking an x-ray, pregnant women are advised to either avoid x-rays or are required to wear a lead apron over the abdominal area if testing is necessary. X-rays cannot pass through the lead in the apron, offering protection for the fetus. Sometimes women of childbearing age prefer to wear a lead apron even if they are not pregnant to protect their reproductive organs. Both male and female examiners may also wear these lead aprons themselves to protect their reproductive organs against any cumulative effects of x-rays.
During the x-ray test
Depending on the area of the body that needs to be x-rayed, the patient will be instructed how to position the body accordingly. An x-ray of an arm may only require the patient to put the arm in a certain position on a table, whereas a chest x-ray will require patients to lie on the table or stand in front of the machine and hold their breath.
The technician (radiographer) who operates the x-ray machine will tell the patient when to move, shift, take a deep breath or perform other actions that may be necessary to take a clear image.
Examples of x-rays that may be used in diagnosing cancer include:
- Chest x-rays to detect lung cancer or Hodgkin’s disease (which may enlarge the chest lymph nodes). Chest x-rays can be taken from either a posterior-anterior view (x-rays pass through the chest from the back to the front) or lateral (x-rays pass through the chest from side to side).
- Mammograms to detect breast cancer. During the test, patients stand in front of an x-ray machine designed for mammography. A technician positions the breast on a platform that holds the x-ray film and raises or lowers the platform depending on the patient’s height. A clear, plastic plate then gradually compresses the breast against the platform. Patients are asked to stand still and hold their breath as images are taken. Usually, multiple images will be taken of both breasts. During a diagnostic mammogram, the technician takes images from various angles and may increase the magnification of images or focus in on areas of concern.
- Bone scans to look for primary bone cancers. The majority of bone cancers can be detected from standard x-rays of the bone. The affected bone may seem ragged instead of solid. On the image the cancer may appear as a hole in the bone, and there may be a mass around the cancer. Often, a radiologist can determine if the tumor is malignant by its x-ray appearance.
- Angiography (x-ray of the blood vessels) to view the arteries that supply blood to a cancer. For example, dye which outlines blood vessels is injected into an artery supplying the liver before the x-rays are taken. The blood vessels are outlined on the pictures, revealing the vessels that supply blood to the liver cancer. Surgeons use the images to determine whether the cancer can be removed and the best procedure.
X-rays also may be taken of the intestines, stomach and kidneys to detect cancer in these organs.
After the x-ray test
Patients can resume normal activities immediately following an x-ray procedure. Either a radiologist or the patient’s physician will interpret the findings and review them with the patient. Depending on the patient’s condition, the physician will review the results with the patient either that same day or at a follow-up visit.
Based on what is detected by the x-rays, additional tests may be necessary for further diagnostic information. These tests could include the following:
- CAT scan. X-ray procedure that produces detailed, cross-section images of the body.
- Magnetic resonance imaging (MRI). An imaging test that uses powerful magnets to produce images of body structures.
- Biopsy. Removal of a sample of tissue, fluid or bone marrow from the body for laboratory analysis.
- Positron emission tomography (PET) scan. A test that can produce three-dimensional images of the body using a tiny amount of a radioactive substance (tracer). It is often used to determine if cancer has spread in the body.
- Radionuclide bone scan. Helps uncover the extent of cancer damage in bone and whether it has spread to other bones. These scans also are done using tracer amounts of a radioactive substance.
Potential risks with x-rays
The levels of radiation used in x-ray procedures are so low that they pose only minimal risk to most 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 might be pregnant should inform their physician or x-ray technologist of their condition. It may be necessary to take certain precautions to protect the fetus.
Some precautions that can be taken before consenting to an x-ray procedure include:
- Ask the physician the reason for the x-ray. 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.
- Keep current on mammography developments. New information is constantly being learned about the proper role of a mammography in preventing and detecting breast cancer. The American Cancer Society (ACS) recommends that women age 40 and older have a mammogram every year. Women who are at higher risk may need to have mammograms more often or earlier in life.
- Request gonad shields when having an x-ray 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 by any patient who wishes to have children in the future. In some cases – such as in x-rays of the pelvic region – 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 stored. 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. In addition, some patients may be given the option of obtaining a copy of their x-rays for their own files.
- Some x-ray procedures require the patient to swallow or to be injected with a contrast medium. In rare cases, patients can experience an allergic reaction to this dye. Patients with a history of such reactions should inform their physician or x-ray technologist. Patients with kidney problems may be harmed by contrast media and may not be permitted to take any.
Treatments that may follow x-rays
If an x-ray and other tests reveal that a patient has cancer, the disease may be treated by a number of therapies. The method of treatment depends on the location, type and stage of the cancer and can include:
- Chemotherapy. Uses powerful drugs to target dividing cancer cells to destroy them and keep them from reproducing and spreading throughout the body. Some normal cells may also be injured with this treatment.
- Radiation therapy. Uses an energy called ionizing radiation to kill cancer cells and shrink tumors. Radiation targets dividing cancer cells and disrupts or destroys their genetic material, preventing the cells from continuing to grow and spread throughout the body. The radiation beams are carefully focused on the targeted area to minimize injury to normal tissue.
- Biological therapy. Various treatments that repair, stimulate or enhance the immune system so that it can better recognize and destroy cancer cells. In some cases, biological therapy can be used to directly attack cancer cells. This therapy is also used to blunt side effects associated with cancer treatments, such as chemotherapy.
- Hormone therapy. Some cancers depend on hormones to grow and spread. Patients who undergo this treatment sometimes take medications that reduce the levels of certain hormones, such as estrogen (in women) and testosterone(in men). In other cases, patients may take drugs that prevent the hormones that help the disease to thrive from attaching to the cancer cells.
- Surgery. Used for the complete or partial removal of a tumor.
- Bone marrow transplants. Replace bone marrow damaged by cancer or cancer treatments with healthy marrow obtained from a donor. Bone marrow contains stem cells that produce red blood cells, white blood cells and platelets necessary for life.
Questions for your doctor regarding x-rays
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctors ore healthcare professional the following questions about x-ray tests:
- What is the purpose of the x-ray?
- What type of x-ray will I need?
- What are the risks involved with the x-ray?
- Where can I have the x-ray done and how long will it take?
- Will I need contrast dye for the test?
- When and from whom will I learn the results of the x-ray?
- Can an x-ray definitively diagnose my suspected cancer?
- Will I need additional tests following the x-ray?
- How can an x-ray affect my fertility?
- Is their a limit to the amount of x-rays I can receive in my life?