CT scans ordered for headaches?

For those who don't know, the CT scanner (Computed Tomography Scanner, or more famously the CAT scanner) is the big donut-shaped device seen in Gray's anatomy or House whenever the doctors have no idea what to do with a patient. It can magically view the insides of a person with great clarity by acquiring x-ray images from multiple angles and computer processing the data to create a salami-thin slice of your gooey insides. Although it is an invaluable tool (imagine hospitals without x-rays, it's practically impossible), the main problem in recent years has been the debate over how often these diagnostic tests should be performed.

Below is a youtube video of what goes on in the scanner as it`s spinning around you (I loved the "patient goes here" caption, hilarious!). It's simply for entertainment purposes.



Now back to the conversation at hand. The only problem is that the x-rays generated are a form of ionizing radiation: electromagnetic energy that can damage living cells and could lead to different forms of cancer. Now, despite sounding like a horror story where everyone will get cancer that undergoes medical imaging, the reality is that the dose of radiation received from a standard chest x-ray is about the same as the dose you get from being outside in the sun all day.

The dosage of radiation received by the CT scanner is a bit more pronounced however; it's the equivalent of getting 200 chest x-rays! And it accumulates, so the more scans you receive over your lifetime, the larger your risk of developing cancer. However, the risks and benefits need to be weighted according to the situation, if you're potentially going to die in the next few minutes from a heart attack, the benefits of getting a diagnostic image far outweigh the small risk of developing cancer 20 years down the road.

The main controversy over the use of these devices is that many physicians are over ordering these tests for minute complaints, such as headaches. A recent paper in the American Journal of Medicine showed that of 623 patients receiving scans for a complaint of headaches, fewer than 2% were found to have any relevant findings on their CT scans. However, there was one patient where the CT image and analysis showed a malignant brain tumor! Something that would be worth catching early on in any case.

What are your thoughts on this issue? Personally I'm quite divided. Being in the medical physics field I'm a huge proponent of medical imaging and it's ability to identify various diseases in patients (like brain tumors), however I think it needs to be used more responsibly on the part of those ordering the tests, many who (at least to the best of my knowledge) seem to have no formal training in the understanding of radiation exposure risks associated with medical imaging.

The paper from the American Journal of Medicine can be found here:
http://www.amjmed.com/article/S0002-9343%2810%2900754-0/abstract