The correct position to determine the image quality indicators (IQIs)

To be of any value in checking the factors defining sharpness and quality, the IQI must be placed on the source side of the specimen. If the source side is not accessible, the IQI is placed on the film side. In the latter position visibility is no longer an indication of geometric unsharpness, but still a check on the developing process and radiation energy used.

What are common image quality indicators (IQIs)?