X-ray Interactions photoelectric and compton scattering are the main ways that x-rays engage with matter.

chapters:
00: 00 Introduction
01: 11 Photo-electric effects
03: 34 Compton Scattering
04: 37 Relative Contribution
05: 53 Summary

For more information and figures from this video on x-ray interactions please see this post on our site:
https://howradiologyworks.com/x-ray-interactions/

When x-rays connect with the human body during an x-ray direct exposure, they form an image that is extremely dependent on the type of interactions of matter and x-rays. Diagnostic x-ray interactions are controlled by 2 various physical interactions– the photoelectric result and Compton scatter.

Understanding the impact of the photoelectric result and Compton scatter and their habits as a function of energy can greatly enhance your capability to pick the very best technical specifications for a provided clinical situation.

We start with a high level summary graphic that shows the distinctions between the x-ray interactions of: photoelectric, compton and meaningful scattering and then go into detail on each of the interactions.

X Ray Interactions
The photoelectric result is the dominant factor to the generation of signal in an x-ray image as the x-ray is can be found in and will be stopped and deposit its energy locally.

The photoelectric result takes place when an x-ray communicates with an electron in the matter. The picture is entirely soaked up and its energy is transferred to an electron that is gotten rid of from the electron cloud.

Considering that the electrons that remain in the inner shells are at a more stable setup the electrons in the external shells will transition to an inner shell and a particular x-ray will be emitted. These secondary events are really low energy and are absorbed fairly in your area and do not contribute to the measured image signal.

The likelihood of such interactions with inner shells depends strongly on atomic number Z (i.e. Z ^ 3), or how many protons are in nucleus.

For that reason, image contrast in x-ray and CT is better for products with high Z elements.

Throughout this interaction, electrons which transfer to the inner shell, maintain energy and emit secondary x-ray photon.

Another crucial point is that the likelihood of interaction is much higher for lower diagnostic x-ray energies, i.e. (1/E ^ 3), where E is the energy of the x-ray photons.

When possible it is typically helpful to utilize lower energy photons for a given imaging job, supplied that they can penetrate the client.

Rad Take-home Point: In the photoelectric impact an x-ray comes in and transfers its energy in your area mainly in an energetic electron (which then deposits its energy locally).

Compton Scattering
Compton Scattering is the second dominant impact in x-ray imaging. In this case, the x-ray photon communicates with an electron in the external shell, and thus the possibility of Compton Scattering does not depend on Z.

X-Ray Interactions with Matter and Image Signal Generation in X-Ray Imaging
As shown in the Figure the X-Ray photon knocks the electron out. The photon goes out in an opposing direction from the knocked out electron in order to conserve momentum.

It is essential to remember here is that unlike in the photoelectric result, the energy is not all deposited in your area.

The spread photon might still have a significant portion of the energy of the incoming photon. It can still travel through the patient and potentially could have a secondary scatter result or might get measured on the detector.

For more information on the impact of x-ray scatter on image quality and the result of technical criteria on x-ray scatter please see our post on x-ray scatter.

Rad Take-home Point: In the Compton impact an x-ray communicates with a weakly bound electron and the electron and photon both continue on in opposing directions.

http://xraytechniciancertification.org/9413-2/