Keywords:
Musculoskeletal spine, CT, Diagnostic procedure, Technology assessment, Radiation safety
Authors:
M. W. Kusk; Esbjerg/DK
DOI:
10.1594/ecr2018/C-2188
Methods and materials
Retrospective study of 20 consecutive patients,
half of whom were scanned with old protocol (120 kVp) and half with new protocol at 150Sn kVp.
Image quality parameters were identical for both protocols : Reference kVp 120,
Quality reference mAs 190,
pitch 0,6,
collimation 192x0,6mm.
In the 150Sn protocol rotation time was increased from 0,5 to 1 second,
to allow enough photons through the tin filter.
CT Dose Index (CTDIvol)and Dose-Length-Product (DLP) was recorded from the scanner generated patient protocol.
Scan range was from outer auditory canal to the disc between first and second thoracic vertebrae.
2 radiologists rated image quality of the upper cervical spine and the shoulder region,
on axial images, reconstructed in 2 mm thickness and 1 mm interval,
using a high resolution kernel (Br59s) and a window/level of 2500/600.
Images were anonymised,
blinded and shown in different order for each radiologist,
using the ViewDEX software.
Rating was on a 5-point ordinal scale,
with 1 being unacceptable for diagnostic.
while 5 indicated optimal image quality.
Statistics were done using Stata 13 IC.
Dose and age differences were tested using t-test,
while image quality was compared using Mann Whitney U test