Measurement of hard tissue density of head phantom based on the HU by using CBCT / 대한구강악안면방사선학회지

ABSTRACT

PURPOSE: The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density (g cm-3) obtained from cone-beam computed tomography (CBMercuRay(TM)) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. MATERIALS AND 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 CBMercuRay(TM)(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 CBWorks(TM). 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, rho (g cm-3), as the dependent variable in terms of the HU(H). The regression equation obtained was rho=0.00072H-0.01588 with an R(2) 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.