Hacker News Reader

Comment by echelon | Hacker News Reader

I got nervous watching him put his hand in front of the machine.

You don't want to subject yourself needlessly to ionizing radiation. A little here and there is probably okay at small doses and for valid reasons, but it all adds up over a lifetime.

He didn't mention how much X-ray radiation this puts out in the first half or so of the video. I worry it's more than a medical photograph as it's continuous high sample rate video, but I'm not an expert. Would be curious to know.

Also curious about the shielding and leaking.

Don't damage your DNA if you don't have to. This is a cool, semi-educational video. I don't think I'd take the same risk though.

View on HN

> He didn't mention how much X-ray radiation this puts out in the first half or so of the video. I worry it's more than a medical photograph as it's continuous high sample rate video, but I'm not an expert. Would be curious to know.

> Also curious about the shielding and leaking.

If you'd watch the video the last part explains exactly that. The energy levels involved, how the beam is stopped, how backscatter is checked. He is definitely no dummy who just found an x-ray machine in a dump and just powered it up for clicks and giggles.

Be rest assured Ben’s previous job was in the medial imaging industry. While he worked on MRI machines rather than ionizing radiation, I think he’s very well aware of the dangers of X rays and has many projects dealing with ionizing radiation. There’s a lot of bad safety science YouTubers, Ben isn’t one of them :)

Funny thing: it’s actually rare to get radiation damage to human hands and feet since there’s not too much growing tissue there!

>there’s not too much growing tissue there!

On the contrary, I was told stories in school that old IR doctors used to lose the hair on their hands after using the fluoro for years. The fingernails are also radiosensitive.

The main reason that X-rays of the hands and feet are usually very low risk is because the beam intensity (dose) required to penetrate the small amount of tissue is very low. Because the video uses a high-sensitivity detector (photon counter) the dose may be even less than usual. However, it would still be a regulatory violation if you did it in a hospital.

I think it's probably not true that it all adds up over a lifetime. That's the model that is widely used but there's some good evidence to suggest it's not accurate.

see: https://en.wikipedia.org/wiki/Linear_no-threshold_model

>I worry it's more than a medical photograph as it's continuous high sample rate video, but I'm not an expert. Would be curious to know.

Typical fluoro skin entrance exposure rate to go through someone's hand is on the order of 1-3 millisieverts per minute. With a more advanced detector (like this one) it may be lower, but increasing the frame rate or resolution will tend to require higher dose rate. The associated risk of skin cancer is quite small. But please be aware that unnecessary X-Ray imaging of living things is against the law in most jurisdictions.

I've wondered how much the average X-ray dosage dropped since they stopped using film and switched to detector-based imaging. Anyone know?

You can compare diagnostic reference levels (DRLs) from different years for the same exam; these correspond to the 75th percentile patient dose for a particular imaging study. It can be a little annoying to find older DRLs (I just tried).

NCRP 172 (published 2015) provides a direct comparison of digital to film for some examinations. For upper GI fluoroscopy without oral contrast the DRL for film is 3.9 mSv and for digital is 1.5 mSv. I think this is roughly typical.

Reply on news.ycombinator.com