I don’t know which to feel more of: amazement at this new X-ray technology and the images it’s produced, or grim respect for what COVID can do to your lung tissue.
In the November 4 issue of Nature Methods, a group of researchers from England, Germany, and France shows how to use ultrabright and focused X-rays (about 10,000,000,000,000 times more powerful than a typical X-ray exam) to reveal the 3-D internal details of organs down to a scale about 100 times smaller than that of a CT scan. The organs used were donated, because even though the imaging is non-destructive, it can mutate the bejeezus out of DNA. No living people need apply.
They made use of the new Extremely Brilliant Source at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, which officially began operations in August of last year.
If you’d like to see in really, really intricate detail what the inside of a human lung looks like, watch this 2-minute video. You just have to click the link and it starts; nothing to download. The first minute shows 3-D views at near actual size, not too unusual for imaging techniques. But then it progresses deeper and deeper, ultimately zooming in to about 100x. I challenge anyone to watch this and not say, “Daaaamn!” or something close to it.
That video was the COVID lung, and despite the wow factor, it’s hard for the viewer to grasp what the disease is specifically doing at those small scales.
So let’s look at some still shots of normal lung vs. COVID lung, also produced by this X-ray technology, to illustrate why you really don’t want any part of this disease.
First, a quick definition: a voxel is a three-dimensional version of a pixel:
In the image below, we have a resolution of 2.5 micrometers (millionths of a meter, µm) per voxel, so the image is made up of cubes having an edge length of 2.5 µm. That is about the size of a single bacterium or a single particulate within automobile exhaust.
First we see that the airspace within the lung tissue of a patient who died of COVID is severely restricted compared to that of a normal lung:
It’s pretty visually apparent why you can’t breathe.
To look at COVID’s effect on recognizable structures within the lung, we focus on the acinus, which is composed of a bunch of little air sacs (sort of like grapes) called alveoli at the end of a bronchial tube. This is where oxygen is absorbed into the blood and carbon dioxide diffuses out of it. Each one of us has about 300 million alveoli in our lungs:
Now that we have an idea of what normal alveoli look like, we can take a look at a 3-D reconstruction of normal alveoli (top) vs. those from a patient who died of COVID (bottom):
Geez. We can see that the alveoli in the COVID patient have literally collapsed, leaving little airspace for the O2-CO2 exchange. In effect, suffocation.
There are other videos included with this study, each not very long but extremely fascinating (again, simply click-n-watch):
Kidney
Brain
Lung (normal)
All of this information will be included in the ESRF-hosted Human Organ Atlas, which also launched November 4 and will continue to develop.
Switching gears for just a moment: If you’re wondering how on Earth a synchrotron produces X-rays, the basic principle is this, from the ESRF’s own explanatory article:
The entire world of synchrotron science depends on one physical phenomenon: When a moving electron changes direction, it emits energy. When the electron is moving fast enough, the emitted energy is at X-ray wavelength.
The electrons at ESRF move fast, all right. They are accelerated to 99.99999964% of the speed of light. The change of direction is provided as they whizz around the huge ring of the synchrotron, not by bending around the circle (though that does itself produce some unfocused X-rays), but because they periodically pass through arrays of magnets called “undulators”. Here magnets cause the high-energy electrons to briefly move in a wavy pattern, so that they change directions a few times and thus emit X-rays. Careful placement of those undulators allows the X-rays to be intensely focused and aimed at a target.
When the electrons are deflected like this by the magnets, they lose some momentum, and that energy has to go somewhere. In the case of the synchrotron, it manifests itself as X-rays that travel in the same direction as the electron was traveling when it decelerated. This phenomenon is known as “Brehmsstrahlung.”
The new synchrotron is being used in a very wide range of applications from nanomaterials to archaeology.
As the world around us seems to collapse into ignorance and insanity, we should be aware that rational, sane, intelligent, hardworking people are continuing to apply the principles of the Enlightenment in an attempt to understand our world and make our lives better. This is one precious facet of our civilization that we must not lose.