More than a “picture” 

A couple of weeks ago, I heard a conversation as triage doctor in a busy ED. A trainee was talking to a young patient about obtaining a chest CT scan: “We’re going to take a picture of your lungs.” I’d also recently heard a similar statement at the dentist’s before a planned cone beam CT scan, “We’d like to get a detailed picture of all your teeth.” 

Neither of the above statements were a true representation of what was being proposed. Clinicians are encouraged to speak in straightforward terms to help patients understand their care plans, but the above were too simplified and inappropriate. While CT scans are invaluable in many diagnostic and therapeutic processes, we shouldn’t ignore their risks completely. 

CT scans are advanced forms of radiological imaging that use ionizing radiation to help image body parts. The radiation beams are much more potent than X-rays and unfortunately, most clinicians aren’t able to estimate radiation doses of CT scans when compared to X-rays. 

Patients need to be made aware of the potential risks of CT scans including radiation exposure and risk of cancer especially with multiple CT scans.

Here are facts to know and share: 

1. A single CT scan can deliver several times the radiation compared to an X-ray.

For example, a CT scan of the chest can be like getting 100 or more Chest X-rays at the same time in terms of the radiation dose. 

2. There’s no level of ionizing radiation that’s completely safe. Every X-ray carries some risk. 

3. The risks are mainly the development of future cancers and the risk of DNA damage.

If DNA damage occurs in reproductive cells, these defects can be passed on to the offspring. 

4. While calculating individual risk from exposure to radiation is very complicated and needs to include age, type of radiation, and tissue type exposed, most doctors need to be aware of the population estimates.

It’s estimated that patients exposed to even moderate doses (10mSV- equivalent to 1-5 CT scans depending on body part and type of imaging) will have a one in a 1000 chance of a future malignancy. 

5. There’s a long latency period before we see any malignancies. Two to four percent of all future cancers are estimated to be caused from exposure to ionizing radiation from medical imaging. 

While technical advances have helped to reduce radiation doses and risks in recent years, it’s not to be overlooked. Believe it or not, survivors of the Hiroshima bombing were exposed to similar levels of radiation. Clinicians must explain diagnostic imaging studies in simple but accurate terms. CT scans aren’t “taking a picture.” Instead, say, “CT scans are a series of X-rays taken at various angles and use computer technology to create detailed images.” Benefits and risks should be clearly explained. Review guidelines for imaging carefully and order advanced imaging only if it’s indicated. Avoid duplication and waste in CT scan utilization. Be extra careful to follow guidelines when ordering CT scans on children and young patients. Finally, we must call for more innovation in this area to make imaging safer for our patients. 

This piece expresses the views solely of the author. It does not necessarily represent the views of any organization, including Johns Hopkins Medicine.