My Doctor Ordered a CT Scan. What Should I Know?

Jun 16, 2016 12:00:00 PM

Posted by Diane Campbell

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If your doctor has ordered a CT scan, you may have lots of questions: Why do I need a CT scan? Why not use another type of imaging? Are there risks involved? Below are answers to some commonly asked questions about CT imaging. Make sure to get satisfactory answers to all of your specific questions before you consent to any medical procedure.


Why should I have a CT scan?

Generally speaking, CT is a non-invasive way for doctors to obtain detailed information about structures in the body. It is especially helpful in obtaining high quality images of skeletal structures as well as of bone, soft tissue, and blood vessels all at once. CT is also used for cancer staging and determining the exact size and location of tumors before surgery. At times, a CT scan may eliminate the need for riskier procedures like exploratory surgery or biopsy.


Are there risks involved?

CT scanning is associated with a very low level of risk. The primary source of this risk is ionizing radiation. CT uses X-rays to capture multiple images from different angles, which are synthesized by a computer into a single image. This allows doctors to “see around” structures that would otherwise obscure a standard, flat X-ray. The National Cancer Institute estimates that an individual risk of developing fatal cancer from a CT scan to be 1 in 2,000 (0.05%), while the average risk of dying of cancer in the U.S. is 1 in 5 (20%).[1] Practitioners must follow guidelines to ensure that CT is used only when necessary, and Iowa Radiology uses dose-reducing software to ensure that when you to have a CT scan, the radiation doseyou receive is the lowest reasonably achievable. 

The other potential source of risk in a CT scan is contrast material. Not all CT procedures require contrast, but those that do commonly use iodine-containing contrast material. Some people experience allergic reactions to iodine that can be severe. Iodine is also contraindicated in combination with certain diabetes medications. [2] Be sure to tell your doctor about all medications that you’re taking as well as any known allergies.


Why not use MRI?

While MRI can offer some of the same benefits as CT without the use of radiation, CT has distinct advantages over MRI in some situations. For example, CT is much faster than MRI, making it ideal in emergencies. As a result, it tends to be the method of choice for detecting internal injuries after an accident. The speed of CT scanning also makes imaging much easier for claustrophobic patients and those who have trouble holding one position for a long time. Also, the powerful magnet in an MRI machine makes it unsuitable for use on patients with certain implanted medical devices or other metallic objects in their bodies.[3]


At Iowa Radiology, we want you to have all the information you need to make wise health care choices and to feel as comfortable as possible during procedures. For more detailed information about CT scanning and various types of CT imaging we perform at our clinics, click below to download our free eBook.


CT Scan Guide


[1] "Computed Tomography (CT) Scans and Cancer." National Cancer Institute, n.d. Web. 29 April 2016.

[2] "Contrast Materials." Radiological Society of North America, n.d. Web. 15 April 2016.

[3] "CT Scan vs. MRI." Differen. Diffen LLC, n.d. Web. 15 Apr 2016.


The information contained in the Iowa Radiology website is presented as public service information only. It is not intended to be nor is it a substitute for professional medical advice.You should always seek the advice of your physician or other qualified healthcare provider if you think you may have a medical problem before starting any new treatment, or if you have any questions regarding your medical condition.

Iowa Radiology occasionally supplies links to other web sites as a service to its readers and is not in any way responsible for information provided by other organizations.


Topics: CT scan

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Iowa Radiology

A compassionate, personal approach to medicine.

Iowa Radiology was founded in 2001 by a group of well-known central Iowa diagnostic professionals who wished to emphasize the personal side of diagnostic care as much as the technical side.


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