A SYSTEMATIC STUDY ON FACTORS AFFECTING PATIENT DOSE : THE FOURTH REPORT : ON CRITERION TO USE OF X-RAY GRID

Abstract

Correlation between the content of scattered X-rays and the criterion to use of X-ray grid are investigated. X-ray grid has been used by radiologic technologists when the content of scattered X-rays is over than 70 percent by their experience. It is studied in this experiment of what does mean to be over than 70 percent of the content of scattered X-rays on radiographic image from the viewpoint with human ability to detect the signal. That is, in the case of that the entropy analysis is introduced into evaluation for the human ability to detect the signal and to transmit the information, it is demonstrated that the human ability to detect the noise-limited signals is remarkedly lowered when the content of scattered X-rays is over 70 percent.