Tuesday, June 12, 2012

Danger of medical imaging

  There is an article on MSNBC about the increase in imaging in the last 15 years. The general idea of the article is great, though not very surprising or novel. A basic summary is that the number of imaging studies have increased, they cost a lot, there is a risk of incidental findings and CT's have a risk of radiation. Unfortunately, as with most pieces of medical journalism, there's a lot that is left out, it's filled with errors and the word choice tries to get the most shock value.
  Here's the title: "MRI, CT scan use spikes, study finds. Should we be worried?" It is true that there are more scans being performed today than ever before, but it has been a gradual increase with the spread of imaging technology throughout the country over the last few decades. That's hardly a "spike." Then, of course, there's the meaningless "Should we be worried?" The proper place for "Should we be worried?" in a title is for a threat that you can't do much about (i.e. "Rat shit found in drinking water. Should we be worried?"). No one is forced to get scans and, although there are a lot of unnecessary scans performed, it is not something that the public needs to start stocking up food rations for. A proper question would be "Should doctors change?"
  The article goes on to talk about magnetic "resource" imaging and PET scans that use MRIs. Both incorrect and a sign of how sloppy this article is. Then, he talks about cost, false positives and this:
The biggest danger of all with scanning comes from CT, or computed tomography. A CT scan exposes the patient to huge amounts of X-rays. One CT scan of the chest, for example, zaps a patient with the same amount of radiation as 150 old-fashioned X-rays. In their survey of medical records, the authors of the latest study found that 3.9 percent of patients were receiving an exposure or more than 50 millisieverts every year. In comparison, that is about the equivalent of the one-time amount that the Japanese government estimates that the nearby residents of the Fukushima power plant got in the hours before they evacuated.
 Yes, CT scans have a large amount of radiation. But, it's disingenuous to pick one of the higher radiation forms CT. High-resolution CT scans looking for specific types of lung disease have the same radiation of "150 old-fashioned X-rays," but most common chest CT's have less than half of that. There are new low-dose CT scans that have less than a tenth of that. I'm not saying that even those low levels are completely safe, but it's not right to make something seem worse than in actually is. What's worse is comparing the amount of radiation exposed to patients over the span of a year, to the high-dose, one-time exposure that the Japanese living near Fukushima got. It makes no sense. Over our lifetimes, cumulatively, we get exposed to an enormous amount of radiation from just normal background sources. That doesn't mean that our daily exposure to cosmic rays is the same as being in an nuclear war zone.
  Overall, MSNBC and Dr. Robert Bazell wasted an opportunity to present the problem of overuse of medical imaging to a biased, mistake-filled useless article that tries to scare people away from all types of imaging.

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