Description du sujet de thèse

X-ray computed tomography reconstructs the three-dimensional internal absorption of an object (e.g., a patient or a material sample) from a series of radiographic projections. This imaging technique is highly sensitive to motion, which introduces artifacts (blurring, loss of contrast). The TIM4Scan project aims to overcome this limitation by developing dynamic reconstruction methods that can directly estimate the four-dimensional displacement field (3D + time) of the volume from the projections themselves. By integrating motion estimation into the reconstruction process, we aim to obtain corrected, high-resolution images even for rapidly moving objects.
This approach will, for the first time, enable imaging of volumes in rapid motion, such as lungs during non-periodic breathing phases or materials under dynamic loading, while simultaneously reducing acquisition times and radiation dose. The project includes experiments on laboratory CT scanners, medical CT systems, and synchrotron facilities. The expected outcomes will enhance imaging capabilities for both materials science and medical applications, benefiting research and clinical diagnosis.

Contexte de travail

X-ray computed tomography (X-ray CT) is a 3D imaging technique that enables the visualization of the internal texture of a specimen in a non-destructive way. Highly developed in a medical context, it is also a standard instrument in research laboratories for studying advanced materials, complex industrial parts, or biological samples. Tomography consists of acquiring a collection of 2D projections (radiographs) around the sample with an X-ray source and a detector. These recorded projections are then used to reconstruct the volume absorption in 3D using a reconstruction algorithm. One strict condition for an accurate reconstruction is that the sample remains perfectly still during the entire acquisition. In case of motion, the quality of the reconstruction will degrade, with blurry texture, ill-defined interfaces, and poor contrast. These low-quality fuzzy volumes cannot be used for qualitative and quantitative analysis. Consequently, imaging a moving sample in 3D is a very ambitious challenge, and breaking this limit would open a new era with enhanced time resolution and low-dose exposure.

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Contraintes et risques

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