Question

Energy subtraction technique takes advantage of the difference in _ during contrast injection:

1. compton scatter
2. tissue density
3. patient thickness
4. k-edge absorption

Answer 1

The energy subtraction technique in medical imaging utilizes the difference in k-edge absorption when a contrast agent is injected, leading to enhanced visualization of body structures.

Step-by-step explanation:

The energy subtraction technique in medical imaging, particularly involving contrast injection, leverages the differences in k-edge absorption. As X-ray energy increases, the Compton effect influences the attenuation of X-rays, which is related to the density of the material and its thickness.

These factors, however, are not as significant in energy subtraction as k-edge absorption. By introducing a contrast agent with a high atomic number, like barium or iodine, the X-rays are absorbed differently, increasing contrast and enabling the visualization of certain body structures. This is because different elements have distinct k-edges, which are the binding energies of the electrons in the K-shell of an atom. When the X-ray energy is just above this edge, there is a drastic increase in absorption, providing a much clearer image of the body part containing the contrast agent.