I have explained this to you twice now, and it sounds like you...

I have explained this to you twice now, and it sounds like you still don't understand. Did you DYOR?

X-ray velocimetry is an advanced measurement technique used to determine the velocity of materials or fluids, in dense or opaque environments where traditional optical methods like Particle Image Velocimetry (PIV) can't penetrate. For example, in the human body.

Particle Image Velocimetry (PIV), let's call this normal velocimetry, is a visualisation technique used to see and measure velocities (speed of movement) of a fluid or gas. It involves illuminating a thin layer of the fluid or gas with a laser light sheet, capturing sequential images of tracer particles within the fluid or gas, and then using computer algorithms to analyse the displacement of the particles to determine the velocity (speed of movement) in the field. This way one can see the movement of the fluid or gas.
For example, through velocimetry you could see the movement of the water around a fish when it swims, something the naked eye couldn't pick up.

Or the air around a cyclist.



Just like visible light, x-ray light picks up tiny particles too. In the first method invented, successive X-ray images are taken at short time intervals from multiple angles, capturing the motion of gases or liquids within the body. A computer algorithm is then used to track the movement of particles showing the movement of air or fluid. Compare to a still image using x-ray, which does not show the movement of the gas or liquid. This would be for XV LVAS, XV Scanner.

Using cross-correlation algorithms (similar to those in PIV), the displacement of features is calculated between frames. Dividing displacement by the time interval gives velocity vectors. Multiple camera angles and computational reconstruction are used to derive the full 3D velocity field.

With a CT scanner, it takes images from multiple angles anyway, however, the CT scanner is tuned in on the particles which may or may not be moving, and a computer algorithm is then used to track the movement of particles, showing movement of air or fluid.

This is a photo of a cyclist. Can you see the air moving?

This is velocimetry. Can you see the air moving?


Here is an x-ray of a lung. Can you see the air moving?


Here is a velocimetry image of a lung. The colour represents where the air faster or slower (its velocimetry).


4DMedical owns the patent on ALL aspects of medical x-ray velocimetry.