Learning objectives
The accuracy control of CT value in Virtual Monochromatic image (VMI) has not been verified.
In this study, we verify whether the CT value of water in VMI is guaranteed. ( Fig. 2 )
Background
In recent years, Dual Energy CT has rapidly become popular. There are several types of Dual Energy CT Technical Approaches( Fig. 3 ).1) Both methods create material decomposition images and VMI and use them for diagnosis. VMI has advantages such as a reduction in exposure dose and a reduction in the amount of contrast agent used, compared to the conventional method of single energy image (SEI).2),3) Therefore, VMI is the most commonly used DECT image in clinical practice.
VMI has the concept of CT values,...
Findings and procedure details
【Methods and materials】
In this study, the CT scanner used was Revolution GSI (GE Healthcare, Milwaukee, Wis, USA), which employs a single-source rapid-switching method( Fig. 7 ).
The QA phantom was set on the CT scanner, and the water part of the phantom was scanned( Fig. 8 ). Every time, the QA phantom was scanned immediately after the simplified calibration. Scans were performed in single energy mode and dual energy mode. Present scan parameters( Fig. 9 ).
The CT value of water was measured from...
Conclusion
VMI has a more significant change in CT value than SEI.
For low keV and high keV images, the CT value accuracy range of the IEC standard may be exceeded.
Care should be taken when measuring CT values of water-like tissue in low keV and high keV images( Fig. 15 ).
Personal information and conflict of interest
T. Kobayashi; Tokyo/JP - nothing to disclose S. Suzuki; Tokyo/JP - nothing to disclose
References
1) Siegel, Marilyn J., et al. "White paper of the society of computed body tomography and magnetic resonance on dual-energy CT, part 1: technology and terminology." Journal of computer assisted tomography 40.6 (2016): 841-845.
2) Shuman, William P., et al. "Prospective comparison of dual-energy CT aortography using 70% reduced iodine dose versus single-energy CT aortography using standard iodine dose in the same patient." Abdominal Radiology 42.3 (2017): 759-765.
3) Matsumoto, Kazuhiro, et al. "Virtual monochromatic spectral imaging with fast kilovoltage switching: improved image quality as...
