What does the nominal incident field mean?

What does the nominal incident field mean? This is a term often mentioned in the imaging department. Today we will briefly introduce it.
First of all, we need to have a definition of the nominal incident field. The incident field is the area where the incident surface n can be used for X-ray pattern projection under certain conditions.
The nominal incident field can be understood as the size of the incident field of the image intensifier obtained when there is a radiation source at infinity that emits parallel ionizing radiation.

Author: X Ray Machine Accessories