Investigation of scatter fractions for estimating leakage dose in medical X-ray imaging facilities

It is essential to make accurate estimates of the scatter of radiation from the human body when calculating the leakage dose in medical X-ray imaging facilities. The scatter fraction varies with the size and shape of the radiation field in a way that is not exactly proportional to the area of the field. Japanese law quotes values for the scatter fraction that are provided by the National Council on Radiation Protection and Measurements, but these data were obtained 30 years ago, using equipment that differed considerably from that employed nowadays. To date, no attempt has been made to confirm whether these data accurately describe current Japanese equipment. In the present study, we used an ion chamber dosimeter to measure scattered radiation fractions, and new scatter factor data are presented that resolve these problems. © 2009 Japanese Society of Radiological Technology and Japan Society of Medical Physics.