What's in part two?
Overview of Part 2 - Image Brightness and Contrast
Within Part 2 - Image Brightness and Contrast you will learn how an X-ray tube produces X-rays and how the passage of X-rays through an object influences which areas on an image are white, black or grey. You will understand the difference between image brightness and contrast and how this affects image quality. The key concept within Part 2 concerns the relationship between object density and radiographic appearances. This will lead onto the method of photodensitometry to estimate object density from radiographs, with specific reference to its use in archaeology.
Syllabus of Part 2 -
X-ray tube physics
Kilovoltage (beam quality or penetrating strength)
Milliampere-seconds (quantity of X-rays over time)
Relationship between image greyscale and object density
Image brightness and contrast
Photodensitometry and its use in archaeology
Estimating object density from a radiograph
Use the quick links below to navigate Part 2 or click on the larger icons at the top of the webpage to take you to an alternative Part of the course.
Part 2 - Image brightness and contrast
2.1 Overview of Part 2
2.2 How are x-rays made?
2.3 Object density and image grayscale
2.4 Photodensitometry
2.5 Summary and quiz
Full course map found within the Course Home Page
There are reading tasks throughout which will help to illustrate these concepts. A list of all reading tasks can be found in the Learning Resources section, along with optional extra literature.
Radiographic science is a large topic and I wouldn't want to inflict upon you a complete explanation of physics, instrumentation and complex nuances.
Likewise, I also wouldn't want to omit anything that is relevant, useful and applicable to paleoradiography.
To mediate between these extremes I have provided you with a working knowledge of how our actions (as x-ray operators) impact upon radiograph appearances. For those who would like to know more about the equipment and physics, I have provided detailed literature within the Learning Resources section.
I have made the assumption that you already know about atoms, electrons, the nucleus and how they differ between elements. If this is not the case, I recommend you view the YouTube video shown below. It's less than 3 minutes long.
James
