Assessment of Entrance Skin Dose for Patients Undergoing Radiography

Abstract

Medical providers use x-rays on patients to diagnose diseases; however, the patients undergoing x-rays will be exposed to radiation. Since X-rays of each machine are different in quantity and quality, it is very important for radiological technologists to calibrate the exposure technique properly for each patient undergoing radiography. Technologists can use the International Atomic Energy Agency (IAEA) Technical Reports Series No. 457 method to evaluate the patient skin dose receiving from x-ray examination. The process begins with the X-ray tube output measurement of the X-ray machine. Then one estimates the trend line from the relationship of kilovoltage peak (kVp) and X-ray tube output.  The result is a model for calculating X-ray tube output as function of various kVp. After that, one can calculate the Entrance Surface Air Kerma value from the technical setting data from kVp, milli-ampere-second (mAs), focus-to-object distance (FOD), and patient thickness. This method can be used to assess the amount of radiation for patient skin dose in different positions, which can be used as the reference dose for each X-ray machine. The benefit of developing this method is that it can be used to control the amount of radiation that the patients receive.