PATIENT SIZE BASED GUIDING EQUATIONS FOR AUTOMATIC mAs AND kVp SELECTIONS IN GENERAL MEDICAL X-RAY PROJECTION RADIOGRAPHY.

A patient size based guiding equation for the automatic selections of mAs and peak voltage kVp in general medical X-ray projection radiography was derived from the first principles of dose and image quality optimization. Under various specific conditions of constant patient size d, kVp or mAs, this equation leads to various longstanding 'rules of thumbs' currently being employed in clinical practice. For automatic mAs control, this work suggests that the current level of dose to patient in X-ray radiography should be halved without compromise image quality. Further studies on the dependence of the absorbed dose on the patient's thickness are required in general X-ray projection radiography.