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Keywords:
Dosimetric comparison, Radiation safety, CT, Radioprotection / Radiation dose, Musculoskeletal spine
Authors:
A. Papachristodoulou1, N. Pliamis1, G. Volford2, R. Markó3, �. Papp3, K. Katsari4, R. Illing3, L. M. J. Best5; 1Thessaloniki/GR, 2Szeged/HU, 3Budapest/HU, 4Athens/GR, 5London/UK
DOI:
10.1594/ecr2016/C-2386
Methods and materials
Study design and patient selection
A retrospective study was performed of data collected from 120 patients that underwent a lumbar spine CT examination in two European centers of Affidea over a 10-month period.
The patients have been categorized in two groups of 60,
with the first group examinations from Evroiatriki Thessaloniki,
Greece and the second group examinations from Péterfy Sándor Hospital,
Budapest,
Hungary.
Mean age was 55,5 years,
male/female ratio 42/78 and mean BMI was 27,6.
Inclusion and exclusion criteria
The study included patients who underwent a non-contrast lumbar spine CT scan for the investigation of disc pathology.
Patients selected were referred for back pain or/and sciatic neuralgia as the main clinical indication.
Patients with a history of trauma or surgery in the lumbar region,
as well as those with known malignancy were excluded from this study.
For the incremental mode scanning,
the study only included examinations with slices oriented parallel to the last 4 intervertebral discs.
Scanning Procedure and Protocols
The two diagnostic centers use the same make and model CT scanner.
Both scanners undergo monthly Quality Control (QC) tests by which the optimal performance of the scanner in terms of image quality and radiation dose is ensured.
The protocol details for each center are presented in Table 1.
Table 1 Protocol parameters
|
CT Lumbar Spine
|
GE 64-slice MDCT LightSpeed VCT
(A)
|
GE 64-slice MDCT Lightspeed VCT (B)
|
Mode of acquisition
|
Incremental
|
Helical
|
Scanning range
|
L2 – S1 vertebral bodies
|
T12 – S1 vertebral bodies
|
Tube potential (kV)
|
120 for (L2-L3,
L3-L4,
L4-L5)
140 for (L5-S1)
|
120
|
Automatic exposure control
|
ON
|
ON
|
Noise Index (NI)
|
15.86
|
21.45
|
Mean mA
|
134
|
127
|
Slice thickness (mm)
|
2.5
|
1.25
|
Interval (mm)
|
5
|
1.25
|
Pitch
|
-
|
0.52
|
Dose reduction (%)
|
30
|
30
|
Data collection and analysis
Both departments use GE HealthCare DoseWatchTM software to assist them in patient dose tracking and dose management. The protocol parameters,
CTDIvol,
DLP and Effective Dose values of each examination were exported from DoseWatchâ„¢.
The values and statistical analysis of the dosimetric data is summarized in Table 3.
Four experienced radiologists reviewed the coded CT data sets.
The images were presented using Biotronics 3Dnet,
a presentation and evaluation of medical images software.
The radiologists working in Hungarian and Greek centers of the Affidea Group rated the images according to the criteria in Table 2.
Fleiss kappa was used to rate inter-rater reliability,
Visual Grading Analysis for observer performance evaluation and ordinal regression analysis to identify differences between the two protocols and their effect on the image quality.
Table 2 Image assessment criteria
Parameters
|
Description
|
Scales
|
Visualisation
|
Structures that must be included within the examination FOV,
vizualized and discriminated according on the pathology being investigated. |
0: Intervertebral disc,
vertebral body,
spinal canal,
intervertebral foramen and surrounding soft tissues are all present and clearly discriminated for evaluation
-2: Intervertebral disc,
vertebral body,
spinal canal,
intervertebral foramen and surrounding soft tissues are not all present and not all are clearly discriminated for evaluation
-1: Intervertebral disc,
vertebral body,
spinal canal,
intervertebral foramen and surrounding soft tissues are present but are not all clearly discriminated for evaluation,
1: Intervertebral disc,
vertebral body,
spinal canal,
intervertebral foramen and surrounding soft tissues are present and have superior visibility for evaluation |
Pathology
|
Defined as disc herniation/bulging,
osseous-spinal cords lesions.
|
1: Pathological findings present
0: Pathological findings absent
|
Localisation
|
Specification of pathology location.
A: Disc,
B: Osseous,
C: Contents of the spinal canal,
D: Surrounding tissues.
If combination of A-D found,
then mark as eg: A+C etc accordingly.
|
A: Disc,
B: Osseous,
C: Contents of the spinal canal,
D: Surrounding tissues.
If combination of A-D found,
then mark as eg: A+C etc accordingly.
|
Confidence level
|
Level of confidence that pathology found is present.
|
0: not confident
1: confident
2: very confident
|