Contribution of the VERITON-CT Camera in Prostate Bone Radiostereotaxy

This is a prospective, single-center, non-randomized study. After a decision in a multidisciplinary consultation meeting, the patient will be offered to join the study. All therapeutic care and clinical follow-up is carried out as part of routine care. Patients will benefit from routine examinations (CT scan, MRI) including a SPECT/CT scan of the bone in the treatment position. Three hours after injection of 9 MBq/kg of 99mTc-HDP, CT imaging followed by whole-body SPECT/CT will be performed on the VERITON-CT (Spectrum Dynamics, Haifa, Israel). In order to make the images in the treatment position, the molding of the BodyFIX (Elekta) compression system that is used to reposition the patient between sessions will be made on the examination bed of the VERITON. It is a mattress that stiffens due to air vacuums. It will be placed on an external radiotherapy tray as for the dosimetry scanner. If it is not possible to take the images under these conditions, the patient will benefit from an examination in the standard position. The images will then be interpreted by a nuclear physician who will identify the targets and define the contours from the SPECT/CT data using the segmentation tools available in the Syngo.via visualization software (Siemens Healthineers, Erlangen, Germany). The images and contours will be anonymized in order to allow blind virtual replanning, at least 6 months before the planning. Non-anonymized images alone will be transmitted as a standard examination, but cannot be incorporated into the treatment plan, as is currently the case. The patient will benefit from a standard dosimetry scanner for treatment planning. The molding of the mattress made during the SPECT/CT scan of the bone will be reused for the dosimetric scanner. The therapeutic procedure will then follow the local protocol and in line with national recommendations. Whole-body SPECT/CT imaging will then be performed at 3 and 6 months on the conventional examination bed. The targets identified during the reference whole-body SPECT/CT will be reused in order to measure the evolution of the SUV quantification.