Though x-ray examinations provide significant benefits to patient as diagnostic tool, but the use of ionizing radiation can cause harm. Amount of x-ray energy absorbed in the patient determine the severity of harm. The patient dose is dependent on operational parameters such as kV, mAs, body orientation (PA, AP etc.), focal-to-skin distance (FSD), field of view (FOV) and filtration and also radiography primarily depend on the Entrance Surface Dose (ESD) and the sensitivity of the organs and tissues that are irradiated during the radiographic examination.
(Corne & Pointon, 2010)In recent years, health physicists have devoted much effort to the minimization of patients’ doses in diagnostic radiology. Through these efforts, substantial reductions in radiation doses to patients resulting from radiographic procedures have been achieved in many countries. The International Atomic Energy Agency (IAEA) has recommended guidance levels of dose for diagnostic radiography for a typical adult patient. IAEA recommended ESD for chest PA is 0.4 mGy.