
X-ray ‘ghost images’ could cut radiation doses - yskchu
http://www.sciencemag.org/news/2018/03/x-ray-ghost-images-could-cut-radiation-doses
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gus_massa
Is this "compressed sensing"? Is "ghost images" an official name or it was
made up just for this article?

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phyzome
I think I've seen this term used before for single-pixel cameras.

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m3kw9
I don’t get if this light source is the x-ray source and how shooting it
through a filter thousands of times lowers radiation?

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VikingCoder
Each detector pixel receives a tiny fraction of the emitted radiation, right?
The problem is that xrays scatter. So it's not entirely obvious what path the
ray took as it passed through the body. That's noise. There are a lot of
techniques to minimize that noise, but it's always there.

Okay, now switch to a single pixel detector, with no filter, and picture if
you left the amount of radiation exposure the same... Well, there's just not
enough information in the signal.

But if you add a spacial filter, and you know its exact structure, then that
gives you a lot of information. And it turns out that the math is such that it
reduces noise A LOT.

So, then you have a choice - keep the radiation the same, and increase the
resolution... Or reduce the radiation, and accept the same resolution you had
before.

Well, you may not be able to actually increase the resolution, for lots of
reasons. So you might not be able to make that trade-off.

I know that's hand-wavy, but I hope it helps.

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petermcneeley
Ya I dont know how much sense this makes. Knowing the final detected position
is information that you are throwing away when you have a single detector. The
ultimate would be to know the exact ray as it entered and then the exact
position (and angle) as its detected.

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VikingCoder
"The ultimate," sure, but in practice that's not going to happen.

Also, don't forget, there are gaps between the pixel detectors. Maybe there's
just not enough information in multiple detectors to make the aggregate signal
loss of those gaps worthwhile.

