Physics & the Detection of X-Rays
X-rays & Matter

X-rays interact with matter in several ways.  When thinking about the detection of x-rays for medical purposes these interactions are important for two reasons.

First, the x-rays will interact with the human tissue (otherwise they would be useless for medical diagnosis).  These interactions can cause damage to cells by either altering their structure or killing them.  This damage needs to be a small as possible.  Thus. a fundamental reason for developing sophisticated detection techniques is to minimize the x-ray dose and thus minimize the probability of damage to cells.

Second, detection devices are built upon the various ways in which x-rays interact.  By taking advantage of the interaction mechanisms designers can create ways to detect very low doses of x-rays.  When the detection device needs a very low dose, the total intensity of the x-rays is small.  Again, the probability of damage to cells is minimized.

The Web sites below provide fundamental information about the interactions of x-rays and matter. Most of the pages that treat the interactions mathematically are written in German.

Interaction Between Penetrating Radiation and Matter
Brief overview that is part of a larger course.

How X-Ray Machines Work for Kids!
Just what it says. Includes history as well as interactions.

Interaction processes of x-ray photons with matter
A table of the energies and the importance of the three major processes by x-rays interact with matter. Part of a larger web site on x-rays.

The Interaction of X-rays with Matter and Radiation Safety
The first half of this PDF file covers the three basic interactions.  Biological effects are covered as well.

Henning Nielsen's slides
This PowerPoint presentation includes slides related to x-ray interaction with matter.  Includes many diagrams and graphs.

Radiologischer Kurs: Röntgenstrahlung
Notes on x-rays.  Includes equations and diagrams.  PDF.

Radiologie Grundlagen
A collection of PowerPoint slides in a PDF file.  Basic interactions are included.

Wechselwirkung Strahlung-Materie
Covers all types of radiation and has a discussion about biological interactions

Elektromagnetische Wechselwirkung von Photonen und Elektronen Mit Materie
Notes for a course.  Includes a mathematical presentation for each of the major interactions.

Wechselwirkung von Photonen mit Materie
PDF file with a large number of PowerPoint slides.  Includes graphs and equations that describe the interactions

Ionisierende Strahlung -Strahlungsarten und ihre Wechselwirkungen mit Materie: Photonen - Elektromagnetische Strahlung
Introduces the basics of x-rays and their interactions with matter.  Includes some equations and diagrams.  This section is part of a long page on ionizing radiation.

The Terrible Power of the Rays
This set of slides and scripts descirbe some of the early tragedies of pioneers in the research and delvelopment of x-ray imaging.  Part of a larger set of materials on the early history of x-rays.

Links for these individual interactions may be added later

Photoelectric Effect
Compton Scattering
Pair Production
Thomson (Rayleigh, coherent) scattering
Photodisintegration

Searches
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Flags indicate the language of the Web site.