Do you believe in magic?
I’ve written a lot of blog posts trying to explain why 3D-DXA (3D-SHAPER) is a scam. However, I’ve had the most success with the following simple exercise.
Please examine the picture above (click on it with the mouse for a full size image). That is a DXA image on the left. It is noisy because it uses low energy X-rays, combines two separate X-rays together and because the X-rays bounce around through the tissue before they reach the detector. I magnified a part of the image so you can see the individual pixels. Each pixel is 0.6 mm times 1.05 mm. Have a closer look at this region. Can you distinguish the cortical bone? Now have a look at region b in the middle of the trochanter. Can you measure the cortical thickness in this region? It is very important that you are completely honest with yourself when answering the following question. Do you really think you can extract a three-dimensional model of the femur with a volume of the bone mineral density values and a surface map with the sub-millimeter cortical thickness as well as the cortical bone mineral density at every point from this noisy, low resolution DXA image?