콘빔형 전산화단층영상에서 HU에 의한 두경부 팬텀 경조직의 밀도 측정

Abstract

Objective: The purpose of this study was to determine a conversion coefficient for Hounsfield Unit(HU) to material density(gcm-3) obtained from cone-beam computed tomography(CBMercuRayTM) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. Methods: CT Scanner Phantom(AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the CBMercuRayTM (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using CBworksTM. Linear regression analysis and Student t-test were performed statistically. Results: There was no significant difference (P > 0.54) between real densities and measured densities. A linear regression was performed using the density, ρ(gcm-3), as the dependent variable in terms of the HU(H). The regression equation obtained was ρ = 0.00072H - 0.01588 with an R2 value of 0.9968. Density values based on the Hounsfield scale was 1697.1±24.9 HU in cortical bone, 526.5±44.4 HU in trabecular bone, 2639.1±48.7 HU in enamel, 1246.1±39.4 HU in dentin of dental head phantom. Conclusion: CBCT provides an effective option for determination of material density expressed as Hounsfield Units.