X-rays are a type of electromagnetic radiation, just like visible light. An x-ray machine sends individual x-ray particles through the body. The images are recorded on a computer or film.
- Structures that are dense (such as bone) will block most of the x-ray particles, and will appear white.
- Metal and contrast media (special dye used to highlight areas of the body) will also appear white.
- Structures containing air will be black, and muscle, fat, and fluid will appear as shades of gray.
How the Test is Performed
The test is done in a hospital radiology department or in the health care provider's office. How you are positioned depends on the type of x-ray being done. Several different x-ray views may be needed.
You need to stay still when you are having an x-ray. Motion can cause blurry images. You may be asked to hold your breath or not move for a second or two when the image is being taken.
How to Prepare for the Test
Before the x-ray, tell your health care team if you are pregnant, may be pregnant, or if you have an IUD inserted.
Certain exams require a special dye, called contrast, to be delivered into your body before the test starts. Contrast helps certain areas show up better on the x-rays.
Let your doctor know if you have ever had a reaction to contrast. You may need to take medicines before the test in order to avoid another reaction.
- Contrast can be given several ways, and depends on the type of CT being performed.
- It may be delivered through a vein (IV) in your hand or forearm.
- It may be given into your rectum using an enema.
- You might drink the contrast before your scan. When you drink the contrast depends on the type of exam being done. The contrast liquid may taste chalky, although some are flavored. The contrast passes out of your body through your stools.
How the Test Will Feel
X-rays are painless. Some body positions needed during an x-ray may be uncomfortable for a short time.
X-rays are monitored and regulated so you get the minimum amount of radiation exposure needed to produce the image.
For most x-rays, the risk of cancer or defects is very low. Most experts feel that the benefits of appropriate x-ray imaging greatly outweigh any risks.
Young children and babies in the womb are more sensitive to the risks of x-rays. Tell your health care provider if you think you might be pregnant.
Adventist Health St. Helena
10 Woodland Road
St. Helena, CA 94574
Please check in at the admissions office. Walk into the front entrance of the medical center and turn left at the front desk. Follow signs for admissions.
To learn more, please call us at (707) 963-6570.