Inobitec DICOM Viewer

3.13. Reconstruction by Series with Varying Distances between Slices

If a series contains images made with a varying step, volume reconstruction by the standard algorithm is impossible. There are two solutions to this problem.

  1. The missing images are interpolated (recreated). In this case, the reconstruction will not be accurate. The DICOM Viewer will return a warning like Series slice distance varies too much: most unique distance: 7.5 mm; min distance: 7.5 mm; max distance: 22.5 mm. Model may be innacurate.
  2. The reconstruction is made within the part of the series where the distances between slices are the same. In this case the reconstruction will be incomplete. The DICOM Viewer will return a warning like Series slice distance varies too much. Only slices 1-22 of 28 are used.

The first method is used by default. For details on how to specify the preferable reconstruction method, see Section 14.5.3.

3.13.1 Remove Bone Tissue Manually

____________________________________________________________________________________________

Functionality is available in the Pro edition
____________________________________________________________________________________________

You can remove the bone tissue for any series specifying the required parameters manually.

To remove the bone tissue manually:

  1. Open the series containing bone tissue in the volume reconstruction window.
  2. Click the Remove bones PIC button on the toolbar. A dialog box will pop up.
  3. Set the Min bones density(HU) value in the dialog box. All tissues whose density exceeds this value will be deleted.
  4. Set the Grow bones () value. This value allows you to set the thickness of the soft bone surface layer in voxels. This layer may have the same density as other tissues. In this case, if you set the minimum bone density value equal to the surface layer density, some tissues other than bones may be removed as well. To avoid this, the minimum bone density is skewed upward, and the soft bone surface layer is deleted using the Grow bones parameter.
  5. Set the Grow tissues (voxels) value. This value allows you to restore other tissues (e.g. vessels inside bones) removed together with the bone tissue. Tissues are restored only in locations contacting the bone tissue.

All these values should be adjusted experimentally. The default values are not optimum.

To remove bone tissues with a lesser density, click the Remove bones PIC button and reduce the minimum bone density value. If the value turns out to be too small, undo the last removal using the Undo PIC button, and increase the minimum bone density value during the next removal.

PIC Some tissues that are different from bone structures may be deleted by mistake. This function should only be used as an auxiliary. The diagnosis should be established on the basis of the original images.

This tool is also available from the Volume main menu item.

3.13.2 Remove Bone Tissue for Fused Series

____________________________________________________________________________________________

Functionality is available in the Pro edition
____________________________________________________________________________________________

This tool is used for angiographic and other studies containing at least one series with contrast and one series without it for the same body area.

To remove the bone tissue:

  1. Fuse the series with contrast and without it in the Series Fusion window (see Section 4).
  2. Open the fused series in the Volume or Multiplanar Reconstruction window.
  3. Select the series with contrast. By default, the first series is selected.
  4. Click the Subtract bones (choose layer to subtruct from first) PIC button on the toolbar. In the dialog that opens, enter the name of the new series. The process may take some time. Upon completion, a series without bones will appear on the series panel for this study. Open this series in the desired mode.
PIC Some tissues that are different from bone structures may be deleted by mistake. This function should only be used as an auxiliary. The diagnosis should be established on the basis of the original images.