Researchers led by Catherine Coolens, PhD, of Princess Margaret Cancer Centre designed and built a phantom that successfully handled routine commissioning tests and performance evaluation for a 320-slice volumetric scanner (Eur J Radiol, 6 August 2018).
While standardization and protocol optimization is essential for quantification of DCE-CT as an imaging biomarker, there currently are no commercially available QA phantoms that can support testing of all imaging parameters pertaining to routine quality control (QC) for contrast-enhanced CT, as well as measuring spatiotemporal accuracy, according to the researchers. As a result, they sought to develop a solid calibration phantom that can perform routine contrast-enhanced CT QA. They also wanted to investigate the sensitivity of contrast-enhanced CT to organ motion and to characterize a volumetric scanner for contrast-enhanced CT.
The investigators created a phantom consisting of an acrylic uniform cylinder containing multiple capsules of varying diameters, orientations, and solid density materials mimicking iodine contrast enhancement. They assessed the sensitivity and accuracy of contrast-enhanced CT measurements on all capsules for a range of scan parameters -- both with and without phantom motion -- along the transaxial axis of an Aquilion One 320-slice volumetric CT scanner (Canon Medical Systems).
The researchers found that the phantom could perform routine commissioning tests such as uniformity, spatial resolution, and image noise. They also determined that partial volume effect and motion blurring both contribute to a general decrease in contrast enhancement. What's more, this dynamic was further dependent on capsule orientation. The effect of blurring is less than 3% for all orientations and phantom speeds when scanning with a rotation time of less than 0.5 seconds, the group concluded.
"Future work will report on the use of this phantom in routine QC as well as multiscanner, multi-institutional trials requiring end-to-end QA for robustness data analysis between scanners," the authors wrote.
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