The skin dose of pelvic radiographs since 1896

Insights into Imaging

Table 3 Different combinations of HV-generator and X-ray tube and their X-ray efficiency ε

#	HV-generator	X-ray tube	Ratio (KfiA pulsed)/(KfiA DC) (ε)		# sources
#	HV-generator	X-ray tube	Average	stand. dev.	# sources
A	Inductor coil	Ion tube	0.69	0.14	12
B	Snook^a	Ion tube	0.72	0.10	14
C1	Snook^a	Coolidge tube	0.56	0.08	9
C2	Transformer^b	Coolidge tube	0.56	0.08	13
D	Inductor coil	Coolidge tube	0.16–0.98^c

^aTransformer with mechanical rectifier [55]. We use the name ‘Snook’ as a generic
^bTransformer and self-rectifying Coolidge tube (one pulse), or transformer with vacuum tube rectifiers and Coolidge tube (one- and two-pulse)
^cTricky combination, coil could easily be overloaded (see Additional file 1: ES XI-D)