Categories
Radiography

Measuring Line Pairs

Spatial resolution using a digital sensor is usually expressed in line pairs per millimeter or lp/mm. Higher resolution sensors do provide more diagnostic data, especially when it is important to see very small details like the tip of a # 10 file. I have written about this recently here.

An important factor to remember is that theoretical resolution is not the same as measured resolution; as such it is a good idea to check to see if the lp/mm claims are measured or theoretical.

My understanding was that the instrument used to measure lp/mm called a phantom maxed out at 20. The scientists and engineers at Schick just advised me that there is now a phantom that can measure up to 28 lp/mm. This photo shows the new Schick 33 sensor 28 lp/mm phantom image. Each line in the zoomed image is only 36µm in width.

Schick 33 - 28lp phantom

Spatial resolution is only one factor in evaluating a sensor. Contrast, software tools, ease of use and customer support are just as important. Most important of all; what is most diagnostic?

More help with digital radiography:

Leave a Reply

Your email address will not be published.