Comparisons of the response of Farmer-Baldwin dosemeters to megavoltage X-rays

The Code of Practice for the dosimetry of photons from 2 to 35 Mv (H.P.A. 1969) assumes that the change in sensitivity with photon energy will be the same for all Farmer-Baldwin chambers, and that consequently an individual chamber need only be calibrated at a single energy in this range, e.g. 2 Mv. The Code refers to theoretical predictions and some experimental measurements in support of this assumption, and since the Code was published Day and Rasoul (1969) have investigated it up to 4 Mv. Since it is essential to the validity of the Code further investigation seemed desirable.