Two dosimetry protocols based on absorbed dose to water have recently been implemented: TG-51 and TRS-398. These protocols use different beam-quality indices: %dd(10)_x and TPR_20,10. The effect of electron contamination in measurements of %dd(10)_x has been proposed as a disadvantage of the TG-51. For actual measurements of %dd(10)_x in five clinical beams (Primus 6–18 MV, SL-75/5 6 MV, SL-18 6–15 MV) a purging magnet was employed to remove the electron contamination. Also, %dd(10)_x was measured in the different ways described in TG-51 for high-energy beams: with a lead foil at 50 cm from the phantom surface, at 30 cm, and for open beam. Moreover, TPR_20,10 was determined. Also, periodic quality-control measurements were used for comparing both quality indices and variation over time, but D_20,10 was used instead of TPR_20,10 and measurements in open beam for the %dd(10)_x determination. Considering both protocols, S_w,air and k_Q were calculated in order to compare the results with the experimental data. Significant differences (0.3% for k_Q) were only found for the two high-energy beams, but when the electron contamination is underestimated by TG-51, the difference in k_Q is lower. Differences in the other cases and variations over time were less than 0.1%.