By Michael Johnson, Assistant Department Manager, Diagnostic Imaging, Samaritan Albany General HospitalWhen you’re hurt or sick, diagnostic imaging is a great tool that let’s medical professionals see inside your body to help diagnose the problem. There are several types of diagnostic imaging and each has different purposes. No need to be in the dark: here’s a sample a what each test is capable of.
X-ray: View Your Bones and Other Anatomy
X-rays are a kind of electromagnetic radiation. When X-rays strike an object, some X-rays will be absorbed and some reflected, depending on the density of the object. Those various densities can be captured as an image on a photographic plate or detector.
The concentration of calcium in our bones absorbs more radiation. X-rays can form a good picture of existing skeletal structures. The X-ray absorbing bones show up as lighter patterns while the softer tissue allows X-rays to pass through and show up as darker tones. Modern X-rays are normally taken by placing a body part (such as an injured arm or leg) in front of an X-ray detector and subjecting it to a short burst of X-rays; the process usually takes less than a second. X-rays can also be taken of the lungs where trapped gases absorb less radiation than the surrounding tissue.
X-ray technology has become a standard and crucial tool for diagnosing a wide range of medical problems. As the number of patients and their medical images accumulate, there are systems in place that allow efficient storage and retrieval of these images. A physician can share X-rays with specialists all over the world for diagnosing and treating special problems, which means better health care for everyone.
Ultrasound: Assess Internal Structures
Ultrasound imaging uses sound waves to produce pictures of the inside of the body. It is used to help diagnose the causes of pain, swelling and infection in the body’s internal organs and to examine a baby in pregnant women, and the brain and hips in infants. It’s also used to help guide biopsies, diagnose heart conditions, and assess damage after a heart attack. Ultrasound is safe and painless.
Ultrasound imaging, also called sonography, involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the probe through the gel into the body. The transducer collects the sounds that bounce back and a computer then uses those sound waves to create an image. Ultrasound examinations do not use ionizing radiation (as used in X-rays), thus there is no radiation exposure to the patient. Because ultrasound images are captured in real-time, they can show the structure and movement of the body’s internal organs, as well as blood flowing through blood vessels.
Computed Tomography(CT) Scan (or CAT scan): Advanced X-ray Imaging
A CT (computed tomography) scan uses special X-ray equipment to take multiple images around the body. A computer then processes the information to produce an image that shows a cross section of the area being examined. To help visualize the process, imagine looking at one end of a loaf of sliced bread. If you pull a slice out of the loaf, you can see the entire slice, from the outer crust to the center. The body is seen on CT scan “slices” in a similar way, from the outer skin to the central part of the body. The exam produces multiple slices showing multiple views of the area being examined. The “slices” can be displayed on a computer monitor and saved for analysis. CT scans can be used to view or diagnose muscle and bone disorders, such as tumors and fractures, diseases such as cancer or heart disease, infections, blood clots and internal injuries.
Magnetic Resonance Imaging (MRI) Scan: Soft Tissue Examination
An MRI scanner uses a powerful magnet and radio waves linked to a computer to create detailed cross-sectional images of the body. The MRI allows the physician to see many different “slices” of a body part. The “slices” can be displayed on a computer monitor and saved for analysis. MRI can be used to view and diagnose the spine, joints, muscles, abdominal tumors and disorders, brain tumors and abnormalities, breast tissue, heart tissue and blood vessels.
Nuclear Medicine: Diagnose Disease
Nuclear medicine imaging uses small amounts of low-level radioactive compounds, which are given as an injection or by mouth (swallowed). These compounds are attracted to specific organs, bones or tissues, which absorb the radioactive material. Once an organ or tissue has absorbed the radioactive material, it produces emissions, which can be detected by a special camera, or scanner. The scanner works with a computer to convert the emissions into an image.
In addition to showing the structure of an organ, nuclear medicine imaging allows the doctor to see how the organ is functioning. A diseased or poorly working organ will appear differently on the scan than will a healthy organ. The information from this test is valuable in diagnosing many diseases, including cancer. Because this test shows internal areas that are not visible on standard X-rays, nuclear medicine imaging can help identify problems very early in the course of a disease. Treatment often is most effective when it is begun in a disease’s early stages.