Focal Spot - Video Lesson

Hey, everybody. Welcome back in this lesson about radiography math. We're talking about focal spot blur. So here's a definition of this topic. Focal spot blur is the blur called the penumbra recorded in the radiograph as a result of geometric factors, including the focal spot size abbreviated FSS as well as the SOD and the OID. Here's an example of the images demonstrating different levels of focal spot blur. In the image to the left, this was created using the ideal geometric factors. You can see the image is very sharp and there's no visible blur on the edges of the structures recorded in the radiograph. In the second two images, we can see an extreme level of focal spot blur. Notice how the edges of all of the objects are fuzzy. We call that blur or penumbra. These images were created with inappropriate geometric factors that resulted in a very high level of blur