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Keywords:
Cardiac, Cardiovascular system, Radioprotection / Radiation dose, CT, CT-Angiography, CT-Quantitative, Diagnostic procedure, Arteriosclerosis, Calcifications / Calculi
Authors:
G. J. Pelgrim1, M. Meyer2, M. Vonder1, M. Greuter1, S. Huijsse1, P. M. Van Ooijen1, M. Oudkerk1, T. Henzler2, R. Vliegenthart1; 1Groningen/NL, 2Mannheim/DE
DOI:
10.1594/ecr2015/C-0622
Results
Tube voltage and IR grade influenced detectability of the calcium spots and calculated calcium scores.
(Figure 2) Using filtered back projection,
25 spots were detected at a tube voltage of 70 kV.
At tube voltages of 100 and 120 kV the detectability of the calcium spots decreased to 17 detected spots at 100 kV and 15 detected spots at 120 kV.
Increased IR strength also decreased the number of detected spots.
This effect was seen at all kV levels and was strongest for 70 kV.
Agatston scores for total phantom calcifications ranged from 12 to 127,
compared to 92 for electron beam CT.
(Figure 3) At 70 kV,
FBP resulted in an overestimation of the Agatston score.
Again,
at increasing grades of IR,
the measured Agatston score gradually decreased.
This effect was visible at all kVs,
but was strongest for 70 kV.
EBT Agatston score was best represented using 70 kV with IR grade 2.
Volume and mass scores were generally underestimated compared to the physical reference values.
Figure 4 and 5 illustrate the mean percentage difference of calculated volume or mass to physical value,
per calcium spot.
The lowest mean difference was around 0.40.
Different trends in mean differences were found for tube voltages and IR strength.
No one combination of scan protocol settings was found to perform best for all calcium score analyses.