Advances in high-dose-rate brachytherapy to treat prostate cancer hinge on improved accuracy in navigation and targeting while optimizing a streamlined workflow. Multimodal image registration and electromagnetic (EM) tracking are two technologies integrated into a prototype system in the early phase of clinical evaluation. We aim to report on the system's accuracy and workflow performance in support of tumor-targeted procedures.
In a prospective study, we evaluated the system in 43 consecutive procedures after clinical deployment. We measured workflow efficiency and EM catheter reconstruction accuracy. We also evaluated the system's MRI-TRUS registration accuracy with/without deformation, and with/without y-axis rotation for urethral alignment at initialization.
The cohort included 32 focal brachytherapy and 11 integrated boost whole-gland implants. Mean procedure time excluding dose delivery was 38 min (range: 21-83) for focal, and 56 min (range: 38-89) for whole-gland implants; stable over time. EM catheter reconstructions achieved a mean difference between computed and measured free-length of 0.8mm (SD 0.8, no corrections performed), and mean axial manual corrections 1.3mm (SD 0.7). EM also enabled the clinical use of a non or partially visible catheter in 21% of procedures. Registration accuracy improved with y-axis rotation for urethral alignment at initialization and with the elastic registration (mTRE 3.42mm, SD 1.49).
The system supported tumor-targeting and was implemented with no demonstrable learning curve. EM reconstruction errors were small, correctable, and improved with calibration and control of external distortion sources; increasing confidence in the use of partially visible catheters. Image registration errors remained despite rotational alignment and deformation, and should be carefully considered.
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2021 Nov 30 [Epub ahead of print]
David Grajales, Samuel Kadoury, Roozbeh Shams, Maroie Barkati, Guila Delouya, Dominic Béliveau-Nadeau, Benedicte Nicolas, William Trung Le, Mustafa-Karim Benhacene-Boudam, Daniel Juneau, Jean N DaSilva, Jean-Francois Carrier, Gilion Hautvast, Cynthia Ménard
Polytechnique Montréal, Canada., Polytechnique Montréal, Canada; Centre Hospitalier de l'Université de Montréal, Canada., Centre Hospitalier de l'Université de Montréal, Canada., Centre Hospitalier de l'Université de Montréal, Canada; Université de Montréal, Canada., Philips Healthcare, Imaging Systems, Netherlands., Centre Hospitalier de l'Université de Montréal, Canada; Université de Montréal, Canada. Electronic address: .