PhD student position : Delivery and models of advanced very-high energy electrons FLASH radiation therapy

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Orsay
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Ensemble hospitalier
CDD

PhD student position : Delivery and models of advanced very-high energy electrons FLASH radiation therapy

 

Context

Radiation therapy is currently one of the main techniques used in cancer treatment. More than 50% of patients treated for cancer - about 180,000 per year in France - benefit from it. Over the last thirty years, numerous technical advances have made it possible to considerably improve the conformation of irradiation to the specific characteristics of each tumour and to reduce their side effects.
Nevertheless, the tolerance of healthy tissues remains the main limitation of this type of treatment, particularly in the case of particularly radiosensitive patients, such as children, for whom controlling the side effects of radiotherapy remains a major therapeutic challenge. Recently, pioneering work conducted at the Institut Curie has shown that ltra-high dose rate irradiation (known as FLASH) has a major effect in sparing healthy tissue - while preserving anti-tumor efficacy (Favaudon et al 2014).

VHEE radiotherapy (very-high energy electrons, in the energy range of 100 to 250 MeV), first proposed in the 2000s, would be particularly accurate and independent of tissue heterogeneities (unlike low energy electrons or protons), and could be applicable in a large number of deep anatomical localizations (see Figure 1) such as the  horacic and intestinal regions. It is also potentially much less expensive than other radiotherapy techniques, and would allow accelerated treatment, for example through  agnetic scanning of particle beams, with high doses per fraction, thereby improving its effectiveness. It is also possible to take advantage of recent work on FLASH - in which a high dose is administered to the tissues in an extremely short time - allowing the simultaneous reduction in the occurrence and severity of early and late complications affecting normal tissues, while maintaining control of the tumour.

 

Missions

In this context, we are looking for a candidate to study the optimisation of an advanced system for VHEE treatments, and its application to FLASH radiotherapy, a potential new paradigm in radiotherapy.

This exciting field of research will be carried out by Thales AVS MIS at the Institut Curie, as part of a strong collaboration between these two institutions.

The Institut Curie, a key player in the fight against cancer, combines a world-renowned cancer research center with a state-of-the-art hospital complex that treats all cancers, including the rarest. Founded in 1909 by two-time Nobel Prize winner Marie Curie, the Institut Curie brings together 3,500 employees at three sites (Paris, Orsay and Saint-Cloud) to carry out the threefold mission of research, care, and the conservation and transmission of knowledge. The thesis will take place in Orsay at the Proton Therapy Center (one of the three technical platforms of the Institut Curie's Radiotherapy Department), and at the U1288 Inserm/Institut Curie laboratory (Laboratoire d'Imagerie Translational en Oncologie - LITO), which develops calculation models based on numerical simulations for oncology and methods for extracting parameters from images, known as radiomic characteristics, facilitating their objective and reproducible quantitative interpretation.

Thales AVS MIS, a branch of the Thales group (80,000 employees, €19 billion in sales in 2018), is a major player in power amplification and radiology. For more than 60 years, Thales AVS, through its "Thales Microwave and Imaging Sub-sytems" (MIS) entity, has been developing and producing radiofrequency tubes, X-ray detectors and power amplification solutions for sectors such as Space, Defence, Medical and Science, with more than 6,000 tubes produced each year. Thales AVS also offers a wide range of flat panel X-ray detectors and medical imaging solutions for digital radiography and fluoroscopy systems. Thales AVS MIS has several industrial centres in Europe (Vélizy, Thonon and Moirans in France, Ulm in Germany) and the thesis will be carried out in collaboration with the Vélizy centre. Thales AVS MIS' multidisciplinary expertise, particularly in electromagnetism, electron acceleration physics or the interaction and transport of particles in matter, combined with a highperformance simulation platform and mastery of vacuum tube technology processes (cathodes, material assembly processes, brazing, deposition, etc.), enables it to envisage the development of a new generation of ultra-compact particle accelerators meeting new needs such as high acceleration gradients, high average power or miniaturization of equipment.

This thesis (CIFRE contract) is part of a collaborative project between the Institut Curie and Thales AVS MIS to develop a new VHEE-FLASH irradiator. The PhD student will therefore carry out simulations based on Monte-Carlo methods to study the propagation of charged particles in various tissues, CT images and patient-adapted digital phantoms.

 

Technical challenges and objectives

  • The clinical effects of VHEE electron beams on cancer treatment cannot be verified by measurements because these types of beams at energies above 50 MeV are not available in current facilities. Therefore, most studies to verify beam characteristics and dose distributions in clinical treatments can only be performed using Monte Carlo simulations. Recent advances in terms of compactness and performance for accelerator technologies with high-gradient cavities make it possible to envisage soon the development of new types of accelerators that could revolutionise radiotherapy. As irradiations with dose rates much higher (several orders of magnitude) than those of conventional radiotherapy present major metrological challenges, work on the delivery and dosimetry of FLASH-VHEE irradiations (monitoring, quality control, absolute dosimetry) is necessary to justify their development and allow the translation of these new radiotherapy techniques into the clinical field. The simulation work and the first experimental characterizations planned in this thesis will feed the future treatment planning models (dose calculation algorithms) as well as the irradiation protocols (calibration protocols) that remain to be developed for this VHEE technique.
  • It is important for the clinical development of VHEE electron beams to consider the contribution to the equivalent dose received by the patient of neutrons, photons and induced radioactivity at very high energy, and to evaluate the production of these secondary particles from the patient point of view.
  • The dose distribution of focused VHEE beams show a depth peak and a favorable dose distribution with reduced proximal and distal dose. The possibility to shape both the on-axis and transverse plane dose distributions of the beam, as well as to create conformal VHEE dose distribution over a large target region, taking into account the constraints of FLASH irradiation has to be evaluated.

These objectives have been defined to provide answers to the problems faced by manufacturers during the development phase of a future VHEE machine (not available today), and by clinicians when defining clinical and dosimetric protocols at such energies. Control of the physical parameters of this new type of treatment will also be the basis of future biological studies to characterise the FLASH-VHEE beams and the consequences of their use on human tissues.

 

General Information

Workplace : Orsay/Velizy (France)
Expected date of employment : Spring 2023 (3 years)
Proportion of work : Full time (50% Curie, 50% Thales)
Supervisors : Dr Irène Buvat and Dr Ludovic De Marzi (Institut Curie), Dr Pascal Girault (Thalès AVS). For informal discussions and further information, please contact irene.buvat@curie.fr, ludovic.demarzi@curie.fr, pascal.girault@thalesgroup.com.
Background : MsC. in Physics, Nuclear or Medical physics or relevant engineering studies. Background in radiotherapy or Monte Carlo simulations is an asset.

Please apply by e-mail before 15th Feb 2023 (CV + application letter + references) to ludovic.demarzi@curie.fr

Exemple : +33112365489
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