Now that we've learned the x-ray system, its components, technique factors, beam modifiers, and other dose reducing tools, we can begin to address what each has on the impact of patient dose, image detail, density, and contrast. Most of this information is review, but there will be some new information as well. 

It has been stated on more than one occasion in this course that there is a constant struggle between patient dose and image quality.  This will again be demonstrated on this page.  Pay attention to this relationship.  If you are able to determine the impact each parameter has on patient dose, you can conclude what will happen to the image quality (and vice versa).

If we INCREASE the following without changing anything else, what happens to the above listed items?

Technique factors


X-ray machine and components


Geometric Considerations

Bottom line for geometric considerations: In order to reduce patient dose and increase image quality, you must use the biggest SID that's reasonable (usually that's 40" or 72" depending on the exam), and you must have the body part as close to the image receptor as possible.