X-ray tests for cancer

ALSO KNOWN AS: Radiology, medical imaging, radiologic procedures, radiographic imaging

DEFINITION: An X-ray test uses a machine to produce radiation passed through a particular body part. The size and density of the part show up as light and dark tones in the image on radiographic film, which helps the doctor diagnose the patient. Radiology encompasses many diagnostic types of imaging. Body parts, regions, and systems that can be seen by radiography include the chest, abdomen, skeletal system (skull, pelvis, spine, facial bones, extremities), brain, sinus, circulatory system (veins, arteries), lymphatic system, glands, muscles, urinary system, digestive system, reproductive system, cysts and tumors, and any soft tissues or organ in the body.

Radiologic exams may include routine X-rays; computed tomography (CT) scans, previously known as a computed axial tomography (CAT) scans; angiography to study the veins and arteries; intravenous urography (IVU), previously known as intravenous pyelogram (IVP), which uses tomography imaging to view the kidneys, ureters, and bladder; upper gastrointestinal (UGI) series, also known as barium swallow, to show the esophagus, stomach, and small intestines; colon imaging, also known as barium enema or lower GI, to demonstrate the large intestine, colon, rectum, and appendix; dental radiography and panoramic tomography, also known as Panorex imaging, to view the teeth, jaw, and tempromandibular joint; sinus radiography to view the paranasal sinus; bone densitometry scans to evaluate bone porosity; digital subtraction angiography (DSA) to illustrate the blood vessels; ER, also known as emergency room, portables, and trauma, to take radiographic images during emergency situations in surgery and in the emergency room; fluoroscopy, which shows an actively moving video image of the part being evaluated; mammography, which takes medical images of the breasts; single photon emission computerized tomography (SPECT) scans which shows an increase in blood flow; and nuclear medicine and positron emission tomography (PET) which use radioactive tracer materials or radiopharmaceuticals that are injected, inhaled, or swallowed by the patient to create images of the whole body and show areas of increased radioactive uptake according to the organ’s functioning ability.

Other imaging technologies that fall outside the scope of X-ray technologies include magnetic resonance imaging (MRI), ultrasound, and endoscopy, which do not use radiation to produce an image. MRI uses a powerful magnet to produce images on film, ultrasound uses sound waves to create images, and an endoscope is a flexible viewing camera inserted orally or rectally to take internal pictures.

Cancers diagnosed: Medical imaging using X-rays is designed to help diagnose cancers, metastases, diseases, fractures, or abnormalities. These diagnostic tests are not to be confused with radiation therapy, which is used to destroy cancers. Most cancers can be seen with radiographic imaging; however, all cancers vary widely in their visibility. Some cancers hide until late in the disease process and then (grow and spread) quickly.

X-ray tests help diagnose bone cancers, bone marrow cancers, soft-tissue cancers, cancers of vital organs, blood-related cancers, lung cancers, lymph node and cancers, spinal cord cancers, abdominal and pelvic cancers, head and neck cancers, liver and gallbladder cancers, reproductive organ cancers, breast cancers, leukemia, esophageal and colon cancers, Hodgkin and non-Hodgkin diseases, advanced skin cancers, brain cancers, and metastases.

Why performed: Diagnostic X-rays are used to identify fractures, pneumonias, cancers, sinus infections, bowel obstructions, foreign objects, and anatomical abnormalities or to confirm that there are no abnormalities. CT, MRI, nuclear medicine scans, and angiography are extremely helpful in locating diseases and cancers that are hard to find. Clinical observation and laboratory tests, combined with X-ray imaging, give the physician a more complete view of the extent of a particular disease. Combining all tests and exams helps the doctor form a treatment plan for the patient. Any of these imaging devices may also be used to assist with guiding a biopsy, in needle placement, or to verify the location of wires and instruments during surgical procedures.

Patient preparation: Because there is such a wide variety of exams and a vast range of reasons for a radiology exam, the patient should consult with the medical doctor or discuss the preparation with the technologist three days before the exam. Some of the tests are routine and involve no preparation. Others may require eating or drinking restrictions, an increase in the amount of fluids in the bladder, or ingestion of contrast preparations for enhanced viewing in certain areas.

Steps of the procedure: The patient should tell the X-ray technician if there is any chance of pregnancy. If pregnancy is not a factor, then the patient is positioned between the X-ray tube and the radiographic film. Depending on the procedure and part being radiographed, the patient may sit, stand, or lie on a table for the exam. A lead shield (radiation protection device) is placed on the area surrounding, but not on, the region to be radiographed. The technique is set according to the size and density of the part. The procedure time varies from five minutes to two hours, depending on the test. Often, several images using different angles are needed. Some X-ray exams require the use of a contrast medium (dye). It may be taken orally or injected into the patient before or during imaging. Contrast materials are used when specific parts need to be enhanced or defined on film.

Contrast materials include barium sulfate (for upper GI and colon studies), iodine-based media (for IVP, CT, and angiography), gadolinium (for MRI), radioactive pharmaceutical materials and radioactive isotopes (for nuclear medicine scans), and xenon gas (for lung scans).

After the procedure: A radiologist will view the X-ray images and document the findings. The report will be given to the patient’s doctor. At a follow-up appointment, the results will be discussed. If the imaging used a contrast material, it is often suggested that the patient drink plenty of fluids to flush the contrast from the body. Over the next several days, the body’s waste products will eliminate the contrast. Depending on the type of contrast and amount used, an unpleasant taste can linger in the mouth for a few weeks.

Although X-rays have long been an important part of diagnosing conditions, including cancers, advancements continued in X-ray technology in the twenty-first century. Efforts to create more precise delivery of radiation have decreased residual damage to healthy tissues. Digital radiography, unlike traditional film and 3D X-ray imaging, has made clearer images, allowing for better diagnosis and more efficient treatment plans. Artificial intelligence and machine learning have enhanced doctors' abilities to interpret X-ray images, which can also be more easily shared within the medical community thanks to technological advancements and electronic medical records. Finally, portable X-ray machines have allowed patients increased access to the technology. 

Risks: The physician will evaluate the patient’s medical situation and determine if the diagnosis and treatment from the radiographic knowledge outweigh the potential risk from the X-rays. If the patient is pregnant, then the procedure may be canceled or rescheduled, or the patient may be double-shielded to protect the fetus. With high-speed film, fast and accurate imaging equipment, collimation, and lead shielding, radiation is kept to a minimum for the patient. Diagnostic X-ray procedures carry no short-term effects; however, any amount of radiation can potentially harm cell structure. High doses of radiation that produce ill effects are seen in radiotherapy for cancer treatments. Long-term or high-dose effects of radiation can cause fetal or genetic defects, mutations or cancers, nausea, diarrhea, vomiting, or death.

In addition to medical and dental X-rays, the general population is exposed to background radiation that increases their total body exposure when they live in a brick house, walk by a brick building, fly in an airplane, smoke or breathe secondhand smoke, live at higher elevation levels, heat their home with natural gas, breathe air pollution, work with natural elements or radiation in their profession, watch television, and work or play on a computer. One can calculate the radiation dose from many potential sources at https://www.epa.gov/radiation/calculate-your-radiation-dose.

Other risks of X-rays include claustrophobia in CT or MRI scanners and allergic reactions to contrast materials. Allergic reactions can include rash, itching, hives, nausea, vomiting, coma, or death.

Results: The radiographic image is developed and viewed by the radiology technician, who gives the film to the physician or radiologist. Depending on the procedure, the patient may receive a preliminary diagnosis or may have to wait until the final report from the radiologist, which may be several days later. The patient’s current health status and extent of disease help determine a treatment plan.

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