CT http://www.3dct.at/cms2/index.php/en/ct 2016-09-26T16:55:16+02:00 www.3dct.at m.reiter@fh-wels.at Joomla! - Open Source Content Management CT-Methodology 2012-07-20T13:27:30+02:00 2012-07-20T13:27:30+02:00 http://www.3dct.at/cms2/index.php/en/ct/ct-methodology Elena Sell elena.sell@fh-wels.at <h1>The CT-Methodology</h1> <table> <tbody> <tr> <td valign="top"> <p style="text-align: justify;">In principle, a 3D-Computertomograph consists of 3 components, the x-ray source, a rotary table on which the sample is mounted and a digital detector. The x-ray source emits an x-ray beam witch spreads cone-shaped. When the x-ray beam penetrates the sample the intensity is attenuated depending on the sample thickness, the density and atomic number of the material. The digital detector converts the x-ray intensity into a digital projection image. To get a 3D-Image of a sample, a full rotation of the sample within the x-ray beam is essential, so the rotary table stops every angle &lt;1° for taking a further projection-image. Depending on the quality of the 3D-Dataset and the sample, 1000-2000 projections are needed to create a 3D-Dataset.</p> </td> <td>&nbsp;</td> <td align="center" valign="top"> <p><img src="http://www.3dct.at/cms2/images/CT-Methodik_Prinzip-CT(de)_300px.jpg" alt="CT-Methodik Prinzip-CT(de) 300px" width="300" height="212" /></p> <address>Figure 1: 3D CT principle</address></td> </tr> <tr> <td valign="top"> <p style="text-align: justify;">To analyse a 3D-Dataset (also called Voxel-dataset), special software is needed. This Software splits the Volume-data into Axial, Frontal and Sagittal slices to display the results on screen, similar to a metallographic preparation. These three slices are orientated to the global coordinate system of the 3D-Dataset. Axial means a slice in X-Y, Frontal in X-Z and Sagittal in Z-Y direction. By different rendering-algorithms, the software can also display a 3D-Image of the measured sample. The different grey values correspond to the material density whereas high density leads to a bright representation and low density to a dark one.</p> </td> <td>&nbsp;</td> <td align="center" valign="top"> <p><img src="http://www.3dct.at/cms2/images/CT-Methodik_CTAuflösung-Objektgrösse%20(neu)_300px.jpg" alt="CT-Methodik CTAuflösung-Objektgrösse (neu) 300px" width="300" height="288" /></p> <address>Figure 2: Dependence of the max. resolution on the object diameter for different CT-systems</address></td> </tr> </tbody> </table> <h1>The CT-Methodology</h1> <table> <tbody> <tr> <td valign="top"> <p style="text-align: justify;">In principle, a 3D-Computertomograph consists of 3 components, the x-ray source, a rotary table on which the sample is mounted and a digital detector. The x-ray source emits an x-ray beam witch spreads cone-shaped. When the x-ray beam penetrates the sample the intensity is attenuated depending on the sample thickness, the density and atomic number of the material. The digital detector converts the x-ray intensity into a digital projection image. To get a 3D-Image of a sample, a full rotation of the sample within the x-ray beam is essential, so the rotary table stops every angle &lt;1° for taking a further projection-image. Depending on the quality of the 3D-Dataset and the sample, 1000-2000 projections are needed to create a 3D-Dataset.</p> </td> <td>&nbsp;</td> <td align="center" valign="top"> <p><img src="http://www.3dct.at/cms2/images/CT-Methodik_Prinzip-CT(de)_300px.jpg" alt="CT-Methodik Prinzip-CT(de) 300px" width="300" height="212" /></p> <address>Figure 1: 3D CT principle</address></td> </tr> <tr> <td valign="top"> <p style="text-align: justify;">To analyse a 3D-Dataset (also called Voxel-dataset), special software is needed. This Software splits the Volume-data into Axial, Frontal and Sagittal slices to display the results on screen, similar to a metallographic preparation. These three slices are orientated to the global coordinate system of the 3D-Dataset. Axial means a slice in X-Y, Frontal in X-Z and Sagittal in Z-Y direction. By different rendering-algorithms, the software can also display a 3D-Image of the measured sample. The different grey values correspond to the material density whereas high density leads to a bright representation and low density to a dark one.</p> </td> <td>&nbsp;</td> <td align="center" valign="top"> <p><img src="http://www.3dct.at/cms2/images/CT-Methodik_CTAuflösung-Objektgrösse%20(neu)_300px.jpg" alt="CT-Methodik CTAuflösung-Objektgrösse (neu) 300px" width="300" height="288" /></p> <address>Figure 2: Dependence of the max. resolution on the object diameter for different CT-systems</address></td> </tr> </tbody> </table>