Computed tomography (CT), sometimes called "computerized tomography" or "computed axial tomography" (CAT), is a noninvasive medical examination or procedure that uses specialized X-ray equipment to produce cross-sectional images of the body. Each cross-sectional image represents a “slice” of the person being imaged, like the slices in a loaf of bread. These cross-sectional images are used for a variety of diagnostic and therapeutic purposes.

CT scans can be performed on every region of the body for a variety of reasons (e.g., diagnostic, treatment planning, interventional, or screening). Most CT scans are performed as outpatient procedures.

How a CT system works

A motorized table moves the patient through a circular opening in the CT imaging system.

While the patient is inside the opening, an X-ray source and a detector assembly within the system rotate around the patient. A single rotation typically takes a second or less. During rotation the X-ray source produces a narrow, fan-shaped beam of X-rays that passes through a section of the patient's body.

Detectors in rows opposite the X-ray source register the X-rays that pass through the patient's body as a snapshot in the process of creating an image. Many different "snapshots" (at many angles through the patient) are collected during one complete rotation.

For each rotation of the X-ray source and detector assembly, the image data are sent to a computer to reconstruct all of the individual "snapshots" into one or multiple cross-sectional images (slices) of the internal organs and tissues.

CT images of internal organs, bones, soft tissue, and blood vessels provide greater clarity and more details than conventional X-ray images, such as a chest X-Ray.

Uses

CT is a valuable medical tool that can help a physician:

• Diagnose disease, trauma or abnormality

• Plan and guide interventional or therapeutic procedures

• Monitor the effectiveness of therapy (e.g., cancer treatment)

Benefits/Risks

When used appropriately, the benefits of a CT scan far exceed the risks. CT scans can provide detailed information to diagnose, plan treatment for, and evaluate many conditions in adults and children. Additionally, the detailed images provided by CT scans may eliminate the need for exploratory surgery.

Concerns about CT scans include the risks from exposure to ionizing radiation and possible reactions to the intravenous contrast agent, or dye, which may be used to improve visualization. The exposure to ionizing radiation may cause a small increase in a person’s lifetime risk of developing cancer. Exposure to ionizing radiation is of particular concern in pediatric patients because the cancer risk per unit dose of ionizing radiation is higher for younger patients than adults, and younger patients have a longer lifetime for the effects of radiation exposure to manifest as cancer.

However, in children and adults, the risk from a medically necessary imaging exam is quite small when compared to the benefit of accurate diagnosis or intervention. It is especially important to make sure that CT scans in children are performed with appropriate exposure factors, as use of exposure settings designed for adults can result in a larger radiation dose than necessary to produce a useful image for a pediatric patient.

CCH Radiology

The Radiology Department at Campbell County Memorial Hospital and the Outpatient Imaging Center in the Stocktrail Building provides diagnostic imaging services to patients in Gillette, Wyoming.

Diagnostic imaging exams provide your health care provider with information about your health. Staff at CCH Radiology are certified in their respective specialties, and most have multiple certifications for different specialties. Learn more about the services available at Campbell County Health Radiology.

Source: FDA