This is explained above, but with a typo saying x-ray velocity instead of x-ray velocimetry.
X-ray velocimetry is a whole new way of using the concept of x-ray to see 'lung function' rather than still lung images. This is done by a process called 'x-ray velocimetry', which 4DMedical owns the patent of, and is the only company in the world to do. 4DMedical brands it XV technology.
Velocimetry is part of physics that measures the movement of gas or liquid in a space. You fire a laser from an angle at said gas or liquid in little bursts, take pictures or a video of the light bouncing back at the same time, and you can see the microscopic particles moving.
4DMedical invented a way of using x-ray instead of lasers for inside the body, with the x-ray entering from multiple angles to see the microscopic particles moving inside the lungs, blood vessels, etc, in the same way a laser picks up the microscopic particles in air or water. This was made possible by the advancements in x-ray technology that now provide extremely detailed images alongside the advancements in digital imaging.
See above for more details. It's the foundations of 4DMedical (not Imbio) and they have the patents for all of it. Noone else can do it but them.
Here is a thread of the two of us discussing it last year:
https://hotcopper.com.au/threads/interpreting-4dx-technology-for-non-doctors.8256760/Here is my explanation from last year:
https://hotcopper.com.au/threads/interpreting-4dx-technology-for-non-doctors.8256760/page-11?post_id=76408211
(20min delay)