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  Metal And Streak Artifacts

To learn about reasons and appearances of such artifacts please visit the sections of our web-site:

Exxim' Technology. Streak Artifact Reduction
Exxim' Technology. Metal Artifact Reduction

  What is SAMARA

SAMARA is an iterative  algorithm for 3D reconstruction, which is more tolerant against input data imperfections than the standard Feldkamp method. Such data imperfections can have any nature, e.g. 

- absorption non-linearities

- scanner geometry misalignment

- non-equidistant angular stepping

- insufficient number of projections (e.g. less than 200).

The technique is designed to reconstruct better images than a standard Feldkamp procedure.  


Application fields: 3D reconstruction of medical and biological objects. (The effectiveness for industrial objects may vary).

The amplitude of streaks should not exceed 500 Houndsfield units.

For uncalibrated systems: up to half of difference between air and water values. 

Typical minimal number of projections: 100


The runtime of the SAMARA reconstruction process in comparison with Feldkamp filtered back-projection:

- for streak artifact reduction approx. 2.5 times longer;
- for metal artifact reduction approx. 3.5 times longer.

  Program Control And Parameters 

The implementation of both Feldkamp and SAMARA algorithms requires the same parameters for scanner and target volume description. However, SAMARA should be supplied with some additional parameters as follows:
- The DC values for air and water (obligatory) unless the whole system is calibrated to Houndsfield units.
- For metal artifact reduction, additionally the DC value of metal (obligatory).
- For non-linear absorption artifact reduction  additionally the "factor of non-linearity compensation" (optional).



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