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Sécurisation des traitements radiothérapeutiques du cancer : validation physique des plans théoriques de radiothérapie par des fantômes dosimétriques anthropomorphes

Abstract : The new radiotherapy treatments, such as stereotactic radiosurgery, Intensity Modulated Radiation Therapy (IRTM) or Volumetric Modulated Arc Therapy (VMAT), require to precisely irradiate the living tissues and to know the effective delivered dose. A computer-based method par TPS (Treatment Planning System), is normally used to define the radiation therapy treatment plan, but it requires specific 3D information. The conventional detectors, such as ionizing chamber, thermoluminescent detectors or films, allow to 1D or 2D measurements whereas, with a chemical dosimeter, it is possible to obtain a 3D dosimetry which allows to control the treatment plan for the patient, independently on the radiation type or on the radiation flux. A chemical gel which presents physico-chemical properties as well as texture morphology proximal to those of biological living tissues, is important in order to control the adsorbed doses in organ-at-risk. In this research two different strategies have been followed, firstly the formulation of new gels, equivalent tissue for breast (adipose tissue) lung and bone has been checked depending their interaction with photons, electrons and neutrons; then their use with low energy photon flow has been verified. The dosimetric characteristics, that have been studied, follow the recommendations of ICRU (International Commission on Radiation Units and Measurements) and show a good agreement between these gels and the biological tissues as recommended by NIST (National Institute of Standards and Technology). Physico-chemical studied have been performed in order to characterize the equivalent tissue gels, such as viscosity, diffusion, mechanical properties, oxygen concentration, gel and cooling time, and the absorbed doses in the conditions of radiation therapy treatment. We have been interested also in validating the equivalent breast gel for low energy photon flow as in the case of Intraoperative radiation therapy using Intrabeam. The final goal was to prepare an anthropomorphic phantom to use in planning the radiation treatment; actually, this first prototype allows to determine the effective delivered dose only near the equivalent lung and bone; some modifications in the IRM sequences as well as in the formulation of the equivalent tissues have been planned to improve the phantom.
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https://tel.archives-ouvertes.fr/tel-03148804
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Submitted on : Monday, February 22, 2021 - 3:11:09 PM
Last modification on : Tuesday, February 23, 2021 - 5:41:33 PM

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  • HAL Id : tel-03148804, version 1

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Jérémy Coulaud. Sécurisation des traitements radiothérapeutiques du cancer : validation physique des plans théoriques de radiothérapie par des fantômes dosimétriques anthropomorphes. Imagerie médicale. Université Paul Sabatier - Toulouse III, 2020. Français. ⟨NNT : 2020TOU30123⟩. ⟨tel-03148804⟩

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