“How many CT scans in a span of one month are considered safe?”
I am a 32 year old female and in the last 2 months I have had two CT scans for my abdominal region. How many CT scans are considered to be safe?
8 Answers
Good question, but a difficult one to answer as CT machines have some variability and it depends on the type of scan involved as well.
Modern day CT scanners incorporate methods to reduce radiation exposure to the patient while still providing good quality images for the radiologist to interpret.
Regarding cancer, you first have to start with the fact that cancer is a common disease and it is estimated that about 42% of a given population will develop cancer in their lifetime, a shocking figure I believe.
For women, the lifetime cancer risk without any radiation exposure is about 37.5%. The exposure you received depends on the machine, the type of scan, and your body (heavier patients require more radiation to penetrate the body).
An average abdominal CT using dose reduction techniques results is an exposure of about 6 millisieverts, abbreviated 6 mSv.
A CT examination with an effective dose of 10 millisieverts (abbreviated mSv; 1 mSv = 1 mGy in the case of x-rays.) may be associated with an increase in the possibility of fatal cancer of approximately 1 chance in 2000. This increase in the possibility of a fatal cancer from radiation can be compared to the natural incidence of fatal cancer in the U.S. population, about 1 chance in 5 (equal to 400 chances in 2000). In other words, for any one person the risk of radiation-induced cancer is much smaller than the natural risk of cancer. If you combine the natural risk of a fatal cancer and the estimated risk from a 10 mSv CT scan, the total risk may increase from 400 chances in 2000 to 401 chances in 2000.
As with many things in medicine, you have to weigh the risks vs. benefits.
Bottom line, your increased risk of cancer from the two scans is likely negligible.
Hope this helps!
Modern day CT scanners incorporate methods to reduce radiation exposure to the patient while still providing good quality images for the radiologist to interpret.
Regarding cancer, you first have to start with the fact that cancer is a common disease and it is estimated that about 42% of a given population will develop cancer in their lifetime, a shocking figure I believe.
For women, the lifetime cancer risk without any radiation exposure is about 37.5%. The exposure you received depends on the machine, the type of scan, and your body (heavier patients require more radiation to penetrate the body).
An average abdominal CT using dose reduction techniques results is an exposure of about 6 millisieverts, abbreviated 6 mSv.
A CT examination with an effective dose of 10 millisieverts (abbreviated mSv; 1 mSv = 1 mGy in the case of x-rays.) may be associated with an increase in the possibility of fatal cancer of approximately 1 chance in 2000. This increase in the possibility of a fatal cancer from radiation can be compared to the natural incidence of fatal cancer in the U.S. population, about 1 chance in 5 (equal to 400 chances in 2000). In other words, for any one person the risk of radiation-induced cancer is much smaller than the natural risk of cancer. If you combine the natural risk of a fatal cancer and the estimated risk from a 10 mSv CT scan, the total risk may increase from 400 chances in 2000 to 401 chances in 2000.
As with many things in medicine, you have to weigh the risks vs. benefits.
Bottom line, your increased risk of cancer from the two scans is likely negligible.
Hope this helps!
Depending on your medical circumstances, CT imaging might be necessary to identify and treat something important. Having said that, it is also important to limit the amount of radiation you get. Two CT scans is unlikely going to be of any consequence. Make sure to ask your physicians about alternative imaging modalities if you need additional imaging. This could include MRI or ultrasound.
I would like to say first that if imaging is necessary for a medical purpose, it is considered safe and appropriate. Each CT of the abdomen and pelvis has a dose of approximately 10 mSv. This is the same as the background radiation dose we are all exposed to in our lives during a 3-year period. Radiologists and radiology technologists try to keep CT doses as low as possible while achieving diagnostic images. The newest CT scanners have the ability to give the same information with lower doses. When possible, if the information is comparable, we will use US or MRI. These modalities do not require radiation.
There is no right number. The main question is: are those medically necessary? If you have a few CTs in a month, it is generally not a big problem, but if every month or year you are having several CTs, then it may increase the chance of problems because radiation has a cumulative effect.
I am not sure why you add the CT scans twice during one month. You have to always weigh the risk versus benefit. If the scan was absolutely necessary to either follow a condition or diagnose a condition, two scans in one month is not a critical situation.
It's all about the risk-benefit ratio. One chest CT is the same amount of radiation as flying from Chicago to Denver. How many flights per month is safe? The answer is, no one really knows, just don't do any unless you have to.
We try to minimize radiation exposure. The decision about whether to do a CT is about the need to diagnose vs trying to avoid radiation exposure. You have not told me what the scans were for so it is hard for me to give a definitive answer.
Robert Cruz
Radiologist
Hello Good question!! Lots to talk about, but...
Answer: try to avoid a single (or multiple) CT scans as much as possible. A single CT increases the risk for you to get cancer in the future years (or might not/not always, it depends on how much of your body has been exposed, or if the machine is properly calibrated to deliver the lowest does of radiation possible, risk also increased with age, young/ under 18 yrs higher risk) cause cancer...but A CT sometimes is quite necessary depending on your condition. Talk to your doctor or a radiologist directly. IS there a CT really necessary (or a 2nd CT)? Is there other imagine modality like ultrasound or MRI that could give us the same (or better) answer. Be careful!! Some private institutions need to pay the lease or the purchase on that machine so they need tons of CT scans to pay the debt off... Always talk to your doctor, ask questions: can the CT be avoided/ or delay (to avoid rapid accumulative radiation dose to your body) if a second CT is necessary for rechecks...
I hope this helps...
cheers!
Answer: try to avoid a single (or multiple) CT scans as much as possible. A single CT increases the risk for you to get cancer in the future years (or might not/not always, it depends on how much of your body has been exposed, or if the machine is properly calibrated to deliver the lowest does of radiation possible, risk also increased with age, young/ under 18 yrs higher risk) cause cancer...but A CT sometimes is quite necessary depending on your condition. Talk to your doctor or a radiologist directly. IS there a CT really necessary (or a 2nd CT)? Is there other imagine modality like ultrasound or MRI that could give us the same (or better) answer. Be careful!! Some private institutions need to pay the lease or the purchase on that machine so they need tons of CT scans to pay the debt off... Always talk to your doctor, ask questions: can the CT be avoided/ or delay (to avoid rapid accumulative radiation dose to your body) if a second CT is necessary for rechecks...
I hope this helps...
cheers!
