1996 tech diving fatality - X-ray?

[rwpatterson357]

The following link describes a fatality that appears to have occured in 1996. My question is about the x-ray. The caption says it shows gas. How does an x-ray show gas in tissue?

http://www.mja.com.au/public/issues/sep2/lawrence/lawrence.html

thanks,
russ

 

[quimby]

Russ,
Good question but you have to remember that a xray, the actual photon itself, is at the mercy of materials that absorb, deflect, and both at the same time. So imagine two xrays traveling through water side by side, one travels through two inches of water and loses A amount of energy, the other goes through one inch of water and a one inch bubble and essentially looses A/2 energy. Now they hit film or Image Intensifier and the first with more energy is going to be darker the the second.
So their not looking at desolved gas its actual bubbles they are talking about. If it had been ultrasound, the bubbles actually reflect higher levels of energy because again the differences in density. Sorry for the desertation but there you go

 

[beche de mer]

rwpatterson357 once bubbled...
My question is about the x-ray. The caption says it shows gas. How does an x-ray show gas in tissue?

thanks,
russ

Gas shows up in X-rays as dark (black) areas. Dense tissues show up as light grey or white.

In the X-ray in the article, look for the following:

In the centre of the X-ray is the heart. (The thing that looks vaguely like a cone, leaning on one side). The heart should be uniformly white. See the black gas in it? In particular the wall of the right atrium (on the left side of the heart as you look at it) is beautifully outlined by gas.

Look at the left lung. (The right one as you look at it.) See how much darker it is than the other one. This is because of gas within the torn lung tissue. The diver evidently suffered pulmonary barotrauma. The gas got there either during ascent or during attempts at resuscitation.

Look at the left side of the neck. (The right side, as you view it.) See the vertical black track, about the width of a finger, passing across the upper ribs? That, I think, is the internal jugular vein. (Too wide for the carotid artery.) It's normally not visible, but can be seen here because it's full of gas.

There are other features also, but those are the main ones.

 

[beche de mer]

And thanks for the link, Russ.

If I'm understanding the fatality report correctly, the set-up that guy was using was suicidal.

He had his bottom mix and his EAN50 both being delivered through a common hose to a common second stage, switching between them via a simple lever switch.

The only way of knowing which mix he was breathing was a piece of yellow tape on the EAN50 hose. Tell me that's going to work at 47m! Not only that, but from the looks of the photo, it could easily be knocked from one setting to another.

When I did my advanced nitrox training, (IANTD), we had a totally independent circuit for our EAN50, which could only be accessed by releasing 2 independent and separate mechanisms.

Unfortunately people are ever more imaginative in finding novel ways to kill themselves.

 

[pipedope]

then the AGE and lack of decompression did.

This points out the need for training on how to handle a toxing diver.

This also points out the reason for having a very solid way to be sure of the gas you are breathing.

 

[Rick Inman]

Quote from article:
"During the inquest the New South Wales State Coroner declined to recommend legislation to regulate recreational technical diving, preferring that it remain subject to a voluntary code of conduct. "

Yeah, that's the part that always worries me. Too many of these and we'll all be subject to State regulations...