Experimental determination of the effective point of measurement in electron beams using a commercial scintillation detector

The EPOM shifts determined in this work agree with calculations by other investigators to within one standard deviation for the A18 and A1SL ionization chambers. This agreement confirms that the AAPM TG51-recommended EPOM shift of 0.5×rcav is not accurate for the A18 and A1SL chambers for electron beam dosimetry. Contrary to previous works, there was no observable trend in the measured EPOM values with electron energy for each chamber.