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Communication Dans Un Congrès Année : 2017

Evaluation of a scattering correction method for high energy tomography

Résumé

One of the main drawbacks of Cone Beam Computed Tomography (CBCT) is the contribution of scattered photons due to the object and detector. Scattered photons are deflected from their original path after interaction with the object. This additional contribution of scattered photons results in increased measured intensities, since the scattered intensities simply add to the transmitted intensity. This effect is seen as overestimated intensities thus corresponding to an underestimation of absorption. This results in artifacts like cupping, shading, streaks etc on the reconstructed images. Moreover, scattered radiation provides bias for quantitative tomography reconstruction (for example atomic number and volumic mass measurement with bienergy technique). The effect can be significant and difficult in the range of MeV energy with large objects due to higher Scattering to Primary Ratio (SPR). Additionally, the incident high energy photons which are scattered by Compton effect are more forward directed and hence more likely to reach the detector. Moreover, for MeV energies, the contribution of photons produced by pair production and Bremsstrahlung process also becomes important. We propose an evaluation of a scattering correction technique based on the method named Scatter Kernel Superposition (SKS). The algorithm uses a continuously thickness-adapted kernels method. The analytical parameterisations of the scatter kernel are derived in terms of material thickness, to form continuously thickness-adapted kernel maps in order to correct the projections. This approach has proved to be efficient in producing better sampling of the kernels with respect to the object thickness. This technique offers applicability over a wide range of imaging conditions and gives users an additional advantage. Moreover, since no extra hardware is required by this approach, it forms a major advantage especially in those cases where experimental complexities must be avoided. This approach has been previously tested successfully in the energy range of 100 keV 6 MeV. The process is based on MCNP simulations in order to take into account both photons and electronic processes in scattering radiation contribution. This paper presents scatter correction results on large objects with a 9 MeV linear accelerator.
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Dates et versions

hal-02417730 , version 1 (18-12-2019)

Identifiants

  • HAL Id : hal-02417730 , version 1

Citer

D. Tisseur, N. Bhatia, N. Estre, L. Berge, D. Eck, et al.. Evaluation of a scattering correction method for high energy tomography. International conference on advancements in nuclear instrumentation measurement methods and their applications, Jun 2017, Liege, Belgium. ⟨hal-02417730⟩

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