Radiation, CT scans, and Cancer

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Radiation, CT scans, and Cancer

A recent set of reports in the Annals of Internal Medicine has
brought to our attention the risk of developing cancer from
excessive CT scans.

The relationship between radiation and cancer is well-established.

Everyone knows that if you get exposed to enough radiation, your
risk of cancer goes up. The more radiation, the more risk of cancer, too.

What is not so well known is that the body retains a memory of every dose
of radiation it experiences. That means if your body turns out to need
say 100 units of radiation to spark a new cancer, an exposure at age 2 to
45 units will actually add to an exposure at age 25 of 40 units, meaning that 
at age 50, all you have to do is be exposed to just another 15 units of radiation
and cancer can be sparked.

What is not known is how much actual radiation in a lifetime is the least 
amount to cause a case of cancer to not only begin, but take hold.

We do know that well under a certain total amount of radiation, there appears to be no 
risk of increased cancer. So, for example, the amount of radiation you
are exposed to when you get a chest X-ray is very minimal, comparable
to the increased exposure you get when flying from Boston to Denver. This
tiny amount does not seem to cause any cases of cancer.

But some X-ray images take a lot more radiation to get the image.
The most is generated by CT scans.  

The least is by MRI scans which generate no X-rays or radiation at all, 
only magnetic fields, which appear to be very, very safe.

But CT scans need to shine alot of radiation on the area under study, to
get all the level of detail necessary to create the incredibly detailed CT image.

The information is so detailed and helpful that the number of CT scans done
in the US has exploded in the last 30 years. This year, the United States will
get 72 million CT scans done. That is 23 times the number done in 1980!

One would hope that with the explosion in the use of CT scans that there would 
also be increased control and caution in the amount of radiation used to do each one.
Turns out, in San Francisco and Alabama, that the amount of radiation turns 
out to be quite variable. The CT scan with the most radiation delivered
13 times as much radiation as the CT with the least, for the same CT
imaging!

The studies published go on to estimate how many cases of cancer are generated
by the use of CT scans in the United States.
Their conclusion was that roughly 23,000 new cases of cancer will be caused
by exposure to CT scan radiation, every year. And that in time there will
be 15,000 deaths from cancer each year in the US from CT scanning.



What is a Reasonable Response?

At Advanced Pediatrics we have developed this stance:

1. We do not recommend you ever get an X-ray or CT scan unless it is clearly needed.
2. If detailed imaging is needed, but an MRI will work as well, we would recommend using an MRI rather than CT.
3. If a CT scan is done, it should be done at a facility known to be able to keep exposure to a very clear and consistent minimum. We are pleased to state that our neighbors in our office building, Advanced Diagnostics, goes to great lengths to keep their use of radiation to the minimum. To that end, they have made a commitment to only use state-of-the-art CT scanners that use a small fraction of the radiation older scanners require.

Bottom Line

• Radiation causes cancer and each exposure is added to subsequent exposures, the body remembers.
• CT scans deliver more radiation than usual X-rays, MRI scans deliver no radiation
• We should avoid getting CT scans unless they are truly necessary.
• Keep in mind that routine X-rays such as chest X-rays and finger and toe films use tiny amounts of radiation. It takes 100-400 chest X-rays to equal one CT scan.
• No X-ray should ever be done without good reason, but CT scans will require more caution in their use than other imaging choices.

Dr. Arthur Lavin

*Disclaimer*
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