CT-Guided Lumbar Nerve Root Injections: Are We Using the Correct Radiation Dose Settings?

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Fig 1.
Measurement of body diameter for a 51-year-old man having an L5 SNRB. A, AP diameter was measured from the lateral scout radiograph at the level of the exiting L5 nerve root. B, Transverse diameter was measured from the frontal scout radiograph at the level of the exiting L5 nerve root.
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Fig 2.
Image analysis score system. A, Grade II represented cases in which the exiting nerve root (arrow) was well delineated and confidently identified. B, Grade I represented cases in which the nerve root (arrow) was identified, but not confidently, and required image window and level manipulation or review of the planning CT images. C, Grade 0 represented cases in which the nerve root could not be identified.

Table 1:

Tube current, fluoroscopy time, patient AP diameter, and CTDI_vol for the 4 proceduralists

	A	B	C	D	P Value
Tube current (mA)	66 (7)	42 (11)	49 (17)	80 (16)	<.0001
Fluoroscopy time (seconds)	10 (5)	6 (5)	12 (7)	14 (10)	.01
AP diameter (cm)	26 (5)	28 (7)	27 (3)	29 (5)	.27
CTDI_vol of CT fluoroscopy (mGy)	88 (50)	34 (25)	78 (54)	149 (113)	<.0001

Table 2:

Image noise by tube current and body AP diameter

Note:—ANOVA was used to evaluate differences in image noise in categories of tube current and body AP diameter. Numbers in parentheses are standard deviations. HU indicates Hounsfield unit.

Table 3:

Subjective image quality by tube current and body AP diameter

Note:—The χ² test was used to evaluate differences in image quality score in categories of tube current and body AP diameter. Numbers in parentheses are row percentages.