Beam hardening manual

The Mpx3GUI application has a built in beam hardening calibration.
To apply this to the image, a number of steps has to be taken. This process will be illustrated below.
More information of the effects and the correction of beam hardening can be found here.


The beam hardening correction uses multiple flat field correction images. These have to be created before the calibration can be applied to the image.
These flat field correction images can be made by placing homogeneous sheets of different thicknesses between the X-ray beam and the detector and then taking an image.
The voltage and amperage of the X-ray beam have to be identical to the settings used to make the original image.
The material should resemble the material of the original image. E.g. aluminum for bones and glass for tissue.

The images produced this way might look as follows:


At least three images should be provided. Somewhere between five and ten is recommended.

Beam hardening window

In the visualization tab of the Mpx3GUI application there is a togglebox that says corrections. Pressing this brings up a screen which has a togglebox that says BH corr.
Pressing that brings up a window where the flat field correction images can be loaded. Note: the image that the beam hardening correction should be applied to has to already be opened in the program.

The beam hardening window can be seen here:


In the window there is an empty box in the upper left corner. Here, correction items can be loaded.
To the right of this, there are a number of buttons that allow adding / manipulating the correction items.
The bottom of the window contains a plot. Here the average signal of each correction item is plotted against its thickness.

Adding a correction item can be done using the Add button. Pressing this opens a small window, shown below.
Here the thickness (in microns) of the sheet that was used to make the flat field correction should be specified. There is also a dropbox where the material can be selected.
This is, however, not necessary for the correction to work. It is purely for administrative purposes.


By pressing Ok, the window closes and an item will have been added to the list. Selecting this item enables a number of buttons.
To load a correction into the correction item, simply press the Load button, or double click the item. This opens a file browser where the correction can be selected.
Correction items can not be overwritten. If the wrong correction is loaded, the correction item has to be removed using the clear button. The item can then be added again.

When at least three items have been added and loaded, the calibration can be started. A progress bar shows the progress. The entire process can take a few seconds.

It is also possible to save / load a list of corrections. This makes use of json files. It can be done by using the Save Json / Load Json buttons.

An example of an image before and after beam hardening is shown below.


Missing functionality

Things that still have to be implemented / might be implemented:

  • Creating the flat field corrections inside the window using the Take Data button.
  • Adding an options menu.
-- Main.cyranoc@nikhefnl - 2016-01-14
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Topic revision: r3 - 2016-01-26 - CyranoChatziantoniou
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