PROPOSAL OF A NEW METHOD FOR ASSESSING THE AMBIENT DOSE EQUIVALENT, WHICH ACCOUNTS FOR THE INFLUENCE OF THE HIGH VOLTAGE IN A MEDICAL X RAY FACILITY

摘要

Two methods of radiological survey in a medical X ray room are compared. The first method is just the usual one, as done today in Brazil. It is based on the election of a high voltage (HV) value, by legal rule the highest used in the clinic, taken as a standard [1]. This highest HV value is supposed to be constant and representative of all others values, which are simply ignored. This work shows that the results of this approach move away a bit from the actual radiation doses, overestimating the values. A second method is proposed and compared with the first one. It takes the various values of HV into account. One should only assume a quadratic relationship between the dose measurements and HV and change the way of workload data acquirement. This second method presents a modified way to calculate the ambient equivalent dose [H*(10)]. It is shown that the spread of values present by the 2nd method is smaller than that of the current one, although in the 2nd method the values are still overestimated, however not too much. Putting both methods side by side, as a conclusion, the second one shows to be better than the first, as it adheres more to the reality.