Technical Terms

Geometric magnification is the ratio of the actual size of the sample to the size of the X-ray image projected on the X-ray camera. This value is the ratio of the distance from the X-ray focal point to the object (FOD) to the distance from the X-ray focal point to the camera (FID).
For example, if an object is placed 100 mm away from the X-ray focus and a camera is placed 400 mm away from it, geometric magnification = FID/FOD = (100+400)/ 100 = 5 [times].
Placing the camera farther away increases the geometric magnification, but reduces the amount of X-rays incident on the camera. To increase the geometric magnification, shorten the FOD (move the object as close to the X-ray tube as possible) to obtain a large geometric magnification.