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by DINKDINK 2903 days ago
>Coloring is arbitrary

By my understanding, it's not possible to determine an objections interaction characteristics with a wavelength of X with a wavelength of Y. (Unless you were able to create some sort of beat frequency tuned to mimic X by sending in Y+delta? Just thinking off the top of my head). It seems fraudulent for the company to say that it's capturing color.

>these type of sensors are able to put different bands to different buckets.

Would the best summarization be, photon counting sensors allow for the capture of x-ray imagine with higher dimensionality?

1 comments

Pretty much. Normal x-ray sensors are like camera sensors and produce an estimate of total energy of the photons / pixel. Photon counting sensors are able to estimate how many photons of certain energy range hit the sensor. So instead of value ’1023’ you might get ’63’ of < 20kv, ’500’ of 20-50kv and ’50’ of > 50kv. So poor mans spectroscopy. Naive way to produce ’color images’ would be to put those buckets to red green and blue channel and now different materials along the beam path might yield equal values with normal x-ray sensors but slightly different colors with photon counting sensors. edit: clarified last sentence
The way "color images" are produced is to map the Hounsfield scale to the visible colour spectrum: i.e. blood red, bone white, steel gray etc.

https://en.wikipedia.org/wiki/Hounsfield_units#Value_in_part...

CT machines have this calibrated as standard, DICOM images have the corresponding fields for the values. Any DICOM viewer will do this (i.e. 3D Slicer, ParaView, OsiriX etc.)

As you say, there is nothing new in this, just PR. Medipix also has been around for a while, it's basically a solid state detector with an integrated USB readout on the silicon. Neither has been invented at CERN, its COTS.

To be more precise, CERN took part in Medipix3's development.

https://medipix.web.cern.ch/medipix3-collaboration-members

Yes, this is a PR release for tech using the Medipix3. If I understand correctly (which I very probably don't since this HN thread is the first time I've heard of this technology), this is analogous to faster/more accurate AI software being developed with some chip company's latest massively parallel processor - representative of real, but nowhere near groundbreaking, technological advancement.

In this case it’s more than HU value LUT though. Photon counting allows per energy bin attenuation to capture more information. It’s cool and promising but costly and not new per se.
Agreed. Photon counting has been around in (medical) imaging for ages.