Table 1.

Characteristics of the radiation qualities chosen for this study.

Radiation quality	Filtration	1st HVL in mm Al				Source of traceability
		25 kV	28 kV	30 kV	35 kV
Mo‐Mo	0.033 mm Mo	0.29	0.32	0.34	0.38	BIPM
Mo‐Rh	0.029 mm Rh	–	0.39	0.41	0.45	PTB
W‐Al	0.5 mm Al	0.31	0.35	0.38	0.44	PTB
W‐Rh	0.048 mm Rh	0.47	0.50	0.51	0.55	PTB
W‐Ag	0.049 mm Ag	0.48	0.53	0.56	0.61	PTB