Type:
Educational Exhibit
Keywords:
Experimental, Not applicable, Image verification, Technology assessment, Physics, CT-Quantitative, CT, Radiographers, Radiation physics, Performed at one institution
Authors:
T. Kobayashi, S. Suzuki; Tokyo/JP
DOI:
10.26044/ecr2020/C-13262
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, just like SECT images. The following equation defines the CT value( Fig. 4 )4).
CT value=(μT−μwater)÷μwater×1000 HU(Hounsfield units)
μT: arbitrary attenuation coefficient
μwater: water attenuation coefficient
This equation shows that even if the spectrum energy is changed, the CT value of water is always adjusted to zero.
The IEC standard specifies an Accuracy test for CT values, which tested using water( Fig. 5, Fig. 6 )5), 6). The accuracy test of CT value should also be performed in VMI.