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Table 2: Group comparisons between selected CT-acquisition parameters for patients receiving CT-guided spinal injections in 2009 and 2010^a
Parameter Anatomy 2009 2010 T Test P Value
Minimum guide-phase tube current (mA) All studies 75.0 ± 61.2 13.4 ± 7.3 <.001
Cervical only 104.0 ± 68.2 16.7 ± 11.2 <.001
Lumbar only 37.7 ± 29.0 11.7 ± 4.9 <.001
Total image series^b All studies 12.3 ± 5.8 9.7 ± 5.4 .022
Cervical only 14.0 ± 6.1 10.9 ± 4.6 .178
Lumbar only 10.8 ± 3.3 9.3 ± 4.9 .269
Survey scan length (mm) All studies 100.4 ± 36.4 94.5 ± 38.9 .436
Cervical only 90.9 ± 56.6 56.6 ± 20.3 .088
Lumbar only 108.0 ± 103.0 103.0 ± 40.0 .816

↵a Mean ± SD.

↵b Note, only 1 series each was assigned to the survey and contrast phases of the procedure; the remainder was during the guide phase.

Parameter	Anatomy	2009	2010	T Test P Value
Minimum guide-phase tube current (mA)	All studies	75.0 ± 61.2	13.4 ± 7.3	<.001
	Cervical only	104.0 ± 68.2	16.7 ± 11.2	<.001
	Lumbar only	37.7 ± 29.0	11.7 ± 4.9	<.001
Total image series^b	All studies	12.3 ± 5.8	9.7 ± 5.4	.022
	Cervical only	14.0 ± 6.1	10.9 ± 4.6	.178
	Lumbar only	10.8 ± 3.3	9.3 ± 4.9	.269
Survey scan length (mm)	All studies	100.4 ± 36.4	94.5 ± 38.9	.436
	Cervical only	90.9 ± 56.6	56.6 ± 20.3	.088
	Lumbar only	108.0 ± 103.0	103.0 ± 40.0	.816