Not Exactly the Transparency in Government We Were Hoping For

[beamjockey]

After singlemaltsilk recently told me that millimeter-wave and X-ray backscatter scanners would soon be in use at Chicago's O'Hare Airport by the Transportation Security Administration, I went looking for more information.


Here is TSA's example of millimeter-wave imaging (with facial features deliberately blurred):

Here is TSA's example of x-ray backscatter imaging:


Here's a description of a backscatter system from one vendor (not necessarily the one deployed at O'Hare). Dose is said to be less than 10 microrems per scan. Americans average about one millirem per day from environmental and medical exposures.

Here's a paper that discusses the risks of squirting X-rays at random travelers, and piously states that the benefits must be balanced against the risks. But it is mighty vague about quantifying the benefits.

(Presumably millimeter RF is less hazardous than X-rays are.)

In the comments of this airport blog, Airline Biz, I found a brilliant suggestion.

Posted by fratermus @ 6:35 PM Fri, Jun 13, 2008

Want to get buy-in? Have each screener post the scans of their own bodies at the entrance to the checkpoint. "Hello. You are being scanned by Tim {pic here}".

If it's no biggie then why not post the scans of the screener (and, hey, the head off the TSA and FAA while we're at it).

If they get to look at us millimeter-nude, we should at least get to look at them millimeter-nude.

An even better idea: Don't use these machines to peer under the clothing of airline passengers, at all.

Comments

[madtechie2718.livejournal.com]

Have a look at these, for image quality:

http://www.caravan-ny.com/th_personal.html

Here's an interesting point - radiologists have been sued for malpractice if they've missed a lesion in, say, a lung, while diagnosing the requested (and different) part of the body - abdomen, let's say.

So, a TSA screener who has medical experience (radiographer, doctor, nurse, failed med student...) may be exposed to a potential lawsuit if a traveller goes through and there is a detectable lesion visible in the image, that is not then acted upon...

I'll have to show some of these images to my chest radiological colleagues - given the spread of TB recently, I have to wonder if it is detectable in images like these - something else for DHS/INS/CDC to get their teeth into?

Or maybe this is just the fine point of a wedge strategy for universal health screening - for frequent travellers...

[beamjockey.livejournal.com]

Looks like they've re-invented the fluoroscope.

I note that the Caravan company's logo appears to show a Saturn V flying over the Moon, which cannot be right. Unless the Lunarians have learned to build copies of the Saturn V.

Could the legal issues you raise be countered by arguments about spatial resolution and signal-to-noise ratio?

[madtechie2718.livejournal.com]

Yes but!

In a case with which I am familiar:

A CT scanner (and also an MR imager) takes a low res scoutview or topogram image, a longitudinal image used only for locating the higher res diagnostic axial images.

At the reporting time, this image is presented, with lines overlaying it to show the location of the axial images. It is not deemed to be of diagnostic quality.

In this case, a request was made to scan a particular part of the anatomy - the scoutview, as is usual, covered a greater chunk of the body than required.

The radiologist reported no lesion seen on the axial images he was asked to review.

Right on the very edge of the scoutview image, in low resolution, was a vaguely suspicious lesion (in retrospect, of course) which later turned malignant.

There is a claim that he should have studied *all* of the data presented - even that outside the specifically requested area, outside his area of exprertise(*) and of non-diagnostic quality, 'just in case'.

Not heard if the case has been resolved. My guess is that the case will not proceed.

(*) IIRC it was a chest radiologist looking at axial chest images and the scoutview extended into the neck, where - with some squinting and if you knew it was there - you could just see a little oddity near the spinal cord in the neck.

Maybe.