Radiation levels and fluence conversion factors

The Code of Federal Regulations defines a radiation area and high radiation area in terms of dose equivalent rate but the manner in which dose equivalent rate is to be determined from measurements of the field has not been prescribed. It is suggested in this investigation that radiation area and high radiation area be defined in terms of effective radiation level which is the rate of change of the maximum dose equivalent in an anthropomorphic phantom placed in the radiation field. A discussion is given on the conversion of physical data describing radiation into the effective radiation level, and the significance of normalization based on fluence and incident fluence is pointed out.