What made me even care about x-ray exposure anyway?

My 6 year old daughter broke her elbow a few weeks ago.  Ouch!

She’s an avid climber.  She loves climbing rocks, trees, snow banks, etc.  She’s had wall climbing lessons.

After she learned about Mt. Everest, she wanted to practice.  So, when we’d walk home from school in the winter she’d climb every snowbank on every front lawn (up the bank, down the shoveled driveway, up the next bank, etc.).  All. The. Way. Home. Every. Day.

A few weeks before she broke her elbow, she was up so high in our neighbour’s maple tree that we couldn’t see her between the leaves.

I reminded her of that yellow-painted line 8 feet up in the climbing class.  That’s the line where you’re not allowed to go above unless you’re properly harnessed and have a belayer.

“Don’t go higher than the 3rd branch” I said; and she got down just fine.

She loves climbing!

And she’s good at it.

We have a tree on our front lawn that is on a slope, so the ground on one side of the tree is higher than the other.  She always gets on and off the side with the higher ground (see the little wooden “step”?).

Except a few weeks ago when she lost her balance.  🙁

We were all getting ready to go out for dinner and ended up at the Emergency Department of the children’s hospital instead.

Of course, they needed to take x-rays to see if there was a break, where the break was, and what kind of break it was.  Of course, diagnostic x-rays are low dose, and rarely have side effects.  Of course in the vast majority of cases the benefits outweigh the risks.

So we had them done.  Two images of her elbow (different angles are used to see the bones from different sides).

She had fractured the end of her humerus (funny bone).

The orthopedic surgeon said that that kind of injury happens when someone lands on their palms with their arms outstretched and elbows locked straight.

The biggest concerns on my mind were:  Can YOU fix her?  HOW are you going to fix her?  And, WHEN will she be fixed?

And over the course of her 2-day stay at the hospital, she had 7 sets of x-rays done (elbow, wrist, neck, more elbow).  She had to take a number of medications.  And she ended up needing a quick surgery to have pins inserted into the bone to properly place it so it would heal straight.

It’s been a few weeks.  The cast is off.  Everything is turning out well, and she is well on her way to recovery.

Then I thought, “I can’t be the only person who wonders about x-ray safety”.

So here’s what I found out to share with you

What are x-rays?  What are their risks and benefits?  As patients, what can we do to reduce any risks?

To sum up the research I did, basically diagnostic x-rays have a very good benefit:risk ratio and in many cases are really needed to identify and diagnose a problem, and to check on healing progress.(1)

Having said that, there are 4 things we can do as patients to reduce our risks even further:

• Ensuring the tests are justified;
• Ensuring the exposures are optimized;
• Tracking the images we’ve had done; and
• Reporting adverse events if they do occur.(1)

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What are x-rays?

Just like light, x-rays are a form of electromagnetic radiation and they are used to diagnose and treat a number of common conditions.(2,3)

In fact, there is a standard amount of naturally occurring “background” radiation that you and I and everyone else are exposed to every day.  This is from naturally-occurring radioactive materials such as radon gas, as well as cosmic radiation from outer space.(4)

They are a “high-energy” light that can go right through the skin and show “shadow-like” images of bones and organs.(2)  And, just like a light bulb, as soon as the machine is turned off, all of the x-rays stop.(3,4)  Medical x-rays are considered to be an “external” exposure, since the patient is exposed to the radiation, NOT the radioactive material itself.(3)  X-ray imaging, therefore does NOT induce radioactivity.(2,4)

Nuclear medicine procedures, on the other hand, use radioactive isotopes that are placed into the body (“internal” exposure) and slowly decay.(2,4)  This occurs, for example, with the use of Iodine-131 for treatment of hyperthyroidism and thyroid cancer, and is not covered in this blog post.(3)

NOTE: X-rays are used for many applications including lower dose diagnostic imaging such as x-rays, mammograms, bone density tests, and CT scans.  In addition to these external diagnostic uses, x-rays are also used to assist with treatments of conditions.  For example, to monitor therapies, and watch complex life saving procedures such as inserting catheters or stents to open partially blocked blood vessels.(1,4)  Fluoroscopy and angiography use x-rays.(2,8)  Radiation therapy is used to treat tumours.(1,2)  None of these are covered in this blog post.

And, for the record, neither ultrasounds nor MRIs use radiation.(2,4)

What are the benefits of having x-rays done?

X-ray imaging is considered to be a valuable medical tool and its use has been a major advance to medicine providing many benefits.(1,5)

X-rays are painless and non-invasive.(1)  They are used for accurately diagnosing conditions (such as broken bones).(1,4)  For example, the most common reason for a CT scan of a child’s head is to look for issues after a head trauma.(6)

Of course, knowing exactly what the problem is (Is it broken? Where is it broken? What type of break is it?) can help to properly fix it!

X-rays are also used to for bone density tests, to better plan surgeries, and to find early stages of cancer, such as in mammograms.(1,4,7)  CT scans use multiple x-rays to create 3-D pictures of an area.(2,8)   These are examples of diagnostic x-rays covered in this blog post.

So, there are definitely benefits to having x-rays done if you need them.  In fact, the risks of refusing or delaying x-rays may very well be greater than the risks of having them done as soon as they’re needed!(6,9)

We want to be accurately diagnosed, right?

What dose of x-rays are we exposed to?

As with medications, you can measure a dose of radiation.  This “effective” dose is measured in units called “milliSieverts” (mSv).(4,10)  Note that with technological advances and to reduce risk, doses of radiation from a single CT scan now are smaller than they were in previous decades.(4,6)

The average person in the US receives an effective dose of about 3 mSv per year just due to natural background exposure.(4)  This is approximately the same dose as 3,000 arm or leg x-rays.

Here is a link to a chart where you can see the amount of radiation from various x-ray tests compared with the background radiation; as well as the estimated added risk of fatal cancer.(4)

As you can see in the chart, an arm (extremity) x-ray would expose you to approximately 0.001 mSv, which is essentially the same as being on earth for 3 hours.  These x-rays are the lowest exposures.(4)

To put this another way, one coast-to-coast commercial flight would expose you to about 0.03 mSv (about 30 arm x-rays).(4)

Since CT scans use multiple x-rays to create a 3-D picture of the area, x-ray exposures for these are a bit higher.(1)  An abdomen/pelvis CT scan and PET/CT would expose a patient to 20-25 mSV, the equivalent of 7-8 years of background radiation.(4)

We’ve all heard that health care workers who work with x-rays every day try to reduce their exposures, and measure and track their exposure(3).  So we should mention why this is so for them, but not for patients.  This is because they’re close to an x-ray machine all day, every working day, and exposure to the rays is not for their own health benefit.

But for patients with medical conditions, the use of x-ray procedures should be based on the health benefit of having the procedure done, versus the risk of not doing it.(3,9,11)

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What are the risks of getting x-rays?

We can all agree that nothing is completely safe, right?

Side effects of diagnostic x-rays are very uncommon.(2,4)

Yes, extremely, horrifically large doses of radiation (100-200 mSv or more), such as atomic bomb exposure, are known to cause cancer.(6,9)  In fact, the data collected from these regrettable incidents is what is used to estimate the cancer risk of low dose x-rays, and that can be a very tricky and crude way of estimating risk for exposures thousands of times smaller!(9)

Small dose medical imaging x-rays rarely cause adverse effects.(2)  However, they do have enough energy to potentially damage DNA which can increase a person’s risk of certain effects such as developing cancer later in life, so we should try to reduce those risks.(1,5)

“The very low radiation doses that are received during imaging procedures generally produce no adverse effects.”(2)

Immediate (deterministic) tissue effects can include red skin at the site of exposure and/or hair loss or cataracts.(1,2,5,10)  Some of these effects have been documented, albeit rarely, after hour-long fluoroscopy procedures.(1,2,10)

Longer term genetic mutation (stochastic) effects can include an increased risk of cancer, infertility, or effects to a developing embryo or fetus.(1,2,8,11)

“The vast majority of medical x-rays do not pose a critical risk to a developing child, there may be a small likelihood of causing a serious illness or other complication”.(4)

Children are more sensitive to x-ray exposure,(2,12) so their dose should be minimized to ALARA (As Low As Reasonably Achievable)(2,4), and the smallest number of images should be taken (8).

“When an individual has a medical need, the benefit of radiography far exceeds the small cancer risk associated with the procedure.”(8)

The risks of developing cancer increase with:

• Higher number of exposures, and/or higher doses of radiation(1,2,10);
• The younger the patient(1,2,10);
• Women are at higher risk for developing radiation-associated cancers(1); and
• Certain organs are more sensitive than others(1,4).

As you can see in the chart, an arm (extremity) x-ray at 0.001 mSv has an estimated added risk for fatal cancer so small it’s considered to be less than 1 in a million (negligible).(4)

And those abdomen/pelvis CT scan and PET/CT scans (20-25 mSV), have an estimated increased risk of fatal cancer of 1 case in 500-1,000 exposures.(4)

In fact, many experts agree that some of the methods that have been used to calculate potential risks from x-ray images are based on data that make it too hypothetical to even be meaningful.(9)  They argue that any risks associated with doses below 50-100 mSv (basically all diagnostic exposures) are actually too small to be measured.(9)  But a few recent reviews of the medical records of over 100,000 patients have shown an increase in risk of certain cancers with increasing exposure of children to CT scans.(6)

One study of in utero x-ray exposure of 10 mSv (approximately the same as 10,000 arm x-rays), showed a 39% increase in malignancies.(10)

“…If a radiological examination is required for the diagnosis or management of an urgent medical problem it must be done, irrespective of whether the patient may or may not be pregnant.”(11)

A study of children exposed to CT scans with an average of 4.5 mSv concluded that there was an average increased risk of cancer of 24%, and that number increased for each additional scan.(6)

Another study of adults who have had an exposure of 10 mSv for heart issues (angiographies or fluoroscopies), their rates of malignancy increased by 3% over a 5-year period.(10)

So, as you can see, very large doses of x-rays can be damaging, especially to children, but regular doses of x-rays for many medical procedures are quite safe.  Of course, we need to consider the risks of not getting a proper diagnosis of your condition, broken bone or seeing damage done from a head trauma say, which may be much higher than the risk of taking those images.

“The clinical benefit of a medically appropriate x-ray imaging exam outweighs the small radiation risk.  However, efforts should be made to help minimize this risk.”(1)

One more risk to consider is the possibility of a reaction to the contrast dye if that’s used in your procedure.(1)  I personally am allergic to it, so that needs to be considered as well.

As patients, what can we do to reduce our risk?

1. Justification (When your doctor recommends that you get an x-ray):

Ask the doctor if x-rays are truly necessary to answer the clinical question.  Have you already had this exact image taken (see point #3) to avoid a duplicate?  Do the benefits substantially outweigh the risks?  Are x-rays the best imaging procedures for your condition?(1,2,5,6,11,13)

If there is a definite clinical reason, the risks of not having your doctor see an x-ray can be greater than the tiny risk of exposure, and it should be done.(1,4,6,8,13)

Two reasons to consider not having an image taken are: 1) If a previous image shows EXACTLY what needs to be known right now, to prevent unnecessary duplication;(2,14) or, 2) If an x-ray is not the best test for your situation, and a different technique would be more suitable.(2)

Since children do have a higher risk, x-ray imaging should be limited only to what is absolutely necessary.(12)

As mentioned before, special considerations should be made for pregnant patients, as there is an increased risk of effects to the fetus, so make sure the doctor knows if there is a possibility that you are pregnant.(1,2,4,11)

“The aim is to minimize exposure to the unborn child.”(2)

Also, if, like me, you’ve had an allergic reaction to an x-ray contrast dye, make sure you tell your doctor!

Remember, if there is an urgent medical problem that requires a radiological exam, it should be done.(11)

2. Optimization (Just before you’re about to have an x-ray done):

Ask the radiologist or technologist what techniques they use to minimize radiation doses for children, and that they take the minimum number of images, and use doses ALARA (As Low As Reasonably Achievable).(1,6,8,9,11,13)

It is important to note here that “reasonably achievable” means that a clear, accurate, quality image is necessary, so a high enough dose of x-rays is needed to properly see the issue without requiring additional images.(2,3,13)

As long as the image contains the necessary information, it should NOT be repeated.(11)

Make sure the radiologist or technologist also knows if there is a possibility that you are pregnant, and they can ensure your abdomen and pelvis are shielded whenever possible.

Regardless of whether you are pregnant or not, shields should be used whenever possible to cover your gonads (ovaries/testes).(11)

3. Keep Records (Right after you had your x-rays done):

Over the course of a lifetime, there may be several times where tests using x-rays are prescribed.  To avoid unnecessary repeat tests, and to keep track of your images, you can use a simple chart that I created for you here.(2,4)

4. Report Radiation Injuries (After you’ve had the x-ray done, and only if you suspect an injury is related to the x-ray):

IF you experience a radiation injury, you should discuss this with your doctor.  Also know that both Health Canada’s MedEffect and FDA’s MedWatch programs accept reports from patients because x-ray machines are regulated medical devices in Canada and the USA.

That, my friends, is what you need to know about diagnostic x-rays!  🙂

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References

1 – http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/default.htm
2 – https://rpop.iaea.org/RPOP/RPoP/Content/InformationFor/Patients/patient-information-x-rays/index.htm
3 – http://www.jacr.org/article/S1546-1440(10)00492-8/abstract
4 – http://www.radiologyinfo.org/en/info.cfm?pg=safety-xray
5 – http://www.ejradiology.com/article/S0720-048X(10)00308-6/fulltext
6 – http://www.bmj.com/content/346/bmj.f2360.full.pdf+html
7 – http://link.springer.com/article/10.1007%2Fs00247-014-3018-9
8 – http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm175028.htm
9 – http://pubs.rsna.org/doi/10.1148/radiol.12112678?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed
10 – http://link.springer.com/article/10.1007%2Fs12350-011-9402-z
11 – http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/safety-code_20-securite/index-eng.php
12 – https://rpop.iaea.org/RPOP/RPoP/Content/SpecialGroups/2_Children/index.htm
13 – http://www.ajronline.org/doi/abs/10.2214/AJR.14.12834
14 – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4075532/