Answer to Question #13292 Submitted to "Ask the Experts"
Category: Medical and Dental Patient Issues
The following question was answered by an expert in the appropriate field:
I had a chest computed tomography (CT) scan about three weeks ago. The hospital staff instructed me to keep wearing my clothes. When the CT was performed, I was wearing a cotton T-shirt and jeans, and my cellphone, car keys, and wallet were in my jeans pockets. I was also wearing my glasses. The hospital staff told me there would be no problem because I was not wearing any metallic objects in the scan area. A few hours after the CT I felt some unpleasant symptoms, including a burning sensation on my back, excessive thirst, and poor breathing. These symptoms and headaches have been affecting me since I had the CT scan. I have visited a doctor and no health issues have been found. I have started to think that something bad happened during the CT because I was wearing my clothes and there were all the objects in my jean pockets. I am terrified about this and hope someone please help me? I have the following questions:
- Could the chest CT have hurt me and be the reason for my symptoms? Is there an increased radiation if a patient is wearing their clothes, cell phone, or other objects, even if they are not in the scan area?
- Can they increase the radiation exposure?
- Could the cellphone (radio frequency) change the settings of the CT scan resulting in an increase in radiation exposure?
- Could these objects absorb radiation and become radiation emitters?
I came back to the hospital and explained my situation and they told me that there is no reason to worry. What can I do to make sure that it is true?
The following are the answers to each of your specific questions you ask:
- Could the chest CT have hurt me and be the reason for my symptoms? No, your symptoms are not from the x-ray radiation.
- Is there an increase in radiation if a patient is wearing their clothes, cell phone, or other objects, even if they are not in the scan area? Can they increase the radiation exposure? There is no significant change in the radiation you receive because of carrying or wearing objects which are not on the area of the body which is scanned. The technologist will make you remove clothing which has metal objects (zippers, jewelry, metal decorations, underwire bras, etc.) that are in the region of the body which is scanned. This is because those items can create distortions (called artifacts) to the image which make it difficult for your doctor to correctly interpret the picture. Large metal objects which are within the region imaged (say a large metal belt buckle when the abdomen is being scanned) could increase the radiation. Metal of the buckle would absorb x rays and decrease the amount of radiation which can reach your organs for imaging. Just as a cell phone camera may turn on its flash if there is not enough light to take a picture, the CT scanner may increase the x-ray intensity to get a good image in this circumstance. This could increase the radiation dose to the patient, but the metal object has to be in the direct CT beam (be in the area imaged) to cause this.
- Could the cell phone (radio frequency) change the settings of the CT scan resulting in an increase in radiation exposure? I am unaware of any cases of a cell phone in some way affecting the behavior of a CT scanner. There is some concern that electronic devices such as implanted pacemakers might be damaged or affected by the direct CT beam, but this is considered to be very unlikely. For further information, see this US Food and Drug Adminstration (FDA) website.
- Could these objects absorb radiation and become radiation emitters? No. Exposure to x rays of the energy and intensity used in a CT scanner will not make things exposed to the beam radioactive.
Jon A. Anderson, PhD, DABR
Professor of Radiology