In oncology, personalized medicine is progressing by providing increasingly tumor- and patient-specific care. Thus, medical imaging allows precise morphological and functional characterization of the tumor by volume measurements, used in particular in radiotherapy to define the macroscopic tumor volume (GTV), and radiomic measurements that correspond to a recent concept of extraction of textural parameters and/or tumor shape (tumor heterogeneity, tumor invasiveness...). Precise characterization of the patient is also possible by anthropometric measurements (measurements of total muscle mass, visceral adipose tissue mass...) which can be important predictive and prognostic factors and which are generally estimated more accurately in imaging than by using mathematical formulas.

However, these measurements are partly dependent on the imaging acquisition mode (PET, CT or MRI). The volume measurements, and therefore the GTV, are thus different depending on the imaging used. Studying these differences is important because no single imaging technique encompasses all potential GTV regions but, on the other hand, a combination of anatomical and functional information could improve tumor delineation. Beyond this volume analysis, the extraction of radiomic characteristics seems very promising in radiotherapy with however many limitations to be overcome, linked in particular to the data acquisition mode. Concerning anthropometric measurements, CT and MRI have become essential techniques for precise anatomical quantification, particularly of lean mass, visceral adipose tissue or muscle mass, but automatic measurement techniques for these parameters have yet to be defined, particularly during CT or MRI acquisitions associated with PET for attenuation correction.

To identify useful volume, radiomic and anthropometric characteristics, medical imaging thus requires prospective cohorts of patients with comparable cancer histologies and standardized images acquired by different modalities (e. g. PET, CT or MRI) during the pre-treatment assessment before similar treatments.

The purpose of this study is to create a prospective cohort to study volume, radiomic and anthropometric characteristics by taking advantage of the recent installation of MRI in the medical imaging department of the Henri Becquerel Cancer Center (HBCC), Rouen, France, allowing PET/MRI to be performed and by taking advantage of the collaboration between the radiotherapy and medical imaging departments of the HBCC.

The purpose of this study is to create a prospective cohort to study volume, radiomic and anthropometric characteristics. For that 60 patients will be included before treatment by radiotherapy.

Patients will benefit from a detailed pre-therapeutic imaging assessment with trimodal acquisitions (CT/MRI/PET with 18F-FDG) before radiotherapy and in radiotherapeutic position according to the "CRAI" (for "Centre Régional de thérapie Assistée par l'Imagerie") acquisition protocol, innovative in trimodality.

This initial imaging assessment will be supplemented by a whole-body biphoton absorptiometry which will be used as a reference examination for certain anthropometric parameters. This examination will be carried out at the Rouen University Hospital in the Rheumatology Department

Inclusion Criteria:

• Positron Emission Tomography before radiotherapy
• More than 18 years
• PS 0 to 1
• Signed Inform consent Form

Exclusion Criteria:

• Contraindication to Magnetic resonance Imaging
• More than 150 kgs
• Pregnancy or child bearing