The study aims at quantifying the registration error obtained in routine patients in
different parts of the prostate and for operators with different experience in order to
assess the average precision of the elastic MR-ultrasound fusion obtained by Koelis™ system.
Patients referred for placement of intraprostatic fiducials before radiotherapy for prostate
cancer will be prospectively offered to enter the study.
The fiducials will be placed under transrectal ultrasound guidance, in the prostate apex,
midgland and base, according to our routine procedure. A 3D Ultrasound acquisition of the
prostate will be obtained at the end of the placement. As per our routine procedure, patients
will undergo unenhanced prostate MRI to control the position of the fiducials. An elastic
fusion of the MR images and the 3D ultrasound acquisitions will be retrospectively performed
by operators of varying experience using the Koelis system. The fiducials (visible on MR and
ultrasound images) will be used to quantify the registration error.