Laurence Autret

Main information about the thesis :
Thesis start : 01/10/2013

Thesis End: February 2017 (no thesis defense)
Title : Reconstruction of 3D dose distribution in external beam radiotherapy using portal imaging

Associated laboratory: LATIM, Brest

In collaboration with the TIMC-IMAG laboratory, Grenoble.

Co-funded by the labex CAMI and the Bretagne region.

 

Only few methods exist for in-vivo dosimetry allowing the determination of an accurate and fully personalized 3D dose distribution for the most current state of the art irradiation techniques. In this work, we propose a 3D dose reconstruction method based on Monte Carlo simulations allowing an accurate and fully personalized dose estimation from an Electronic Portal Imaging Device (EPID). This previously proposed method supposes that the cumulative dose distribution inside the patient can be related to the cumulative dose deposition in the EPID using kernel matrices. These matrices represent patient and EPID dose responses to a set of impulsional sources and they can be estimated using Monte Carlo (MC) simulations. To enable its use in a clinical context, a previously proposed methodology has been adapted, taking advantage of the sparsity of the matrix system linking the patient cumulative dose distribution to the EPID cumulative dose deposition. In addition, Graphic Processing Units (GPUs) were used in kernel matrix estimations in order to reduce the associated estimation computational time. The validation of this proposed sparse dose reconstruction was first realized on simulated datasets. An EPID image was simulated and recorded to perform a 3D dose reconstruction for a head and neck patient CT. Simulated and reconstructed dose distributions within the patient show good agreement. In conclusion, the proposed approach allows a clinically feasible 3D dose reconstruction in external beam radiotherapy using portal imaging.

PhD main scientific communications :

  1. Autret, L.; Bert, J.; Benhalouche, S.; Desbat, L. & Visvikis, D.
    Reconstruction of 3D dose distribution in external beam radiotherapy using portal imaging SURGETICA, 2014
  2. Autret, L.; Bert, J.; Desbat, L. & Visvikis, D.
    3D dose reconstruction in external beam radiotherapy using portal imaging IEEE Nuclear Science Symposium and Medical Imaging Conference, 2015
  3.  Autret, L.; Bert, J.; Lemarechal, Y.; Desbat, L. & Visvikis, D.
    3D dose reconstruction in external beam radiotherapy using portal imaging Recherche en Imagerie et Technologies pour la Santé, 2015

Thesis poster :