Magnetic Resonance Imaging-Guided Adaptive Radiation Therapy: A “Game Changer” for Prostate Treatment?

Abstract

Radiation therapy to the prostate involves increasingly sophisticated delivery techniques and changing fractionation schedules. With a low estimated α/β ratio, a larger dose per fraction would be beneficial, with moderate fractionation schedules rapidly becoming a standard of care. The integration of a magnetic resonance imaging (MRI) scanner and linear accelerator allows for accurate soft tissue tracking with the capacity to replan for the anatomy of the day. Extreme hypofractionation schedules become a possibility using the potentially automated steps of autosegmentation, MRI-only workflow, and real-time adaptive planning. The present report reviews the steps involved in hypofractionated adaptive MRI-guided prostate radiation therapy and addresses the challenges for implementation.

Clinical implementation of magnetic resonance imaging guided adaptive radiotherapy for localized prostate cancer

“…The clinical implementation of (daily adapted) MRgRT constitutes a major logistic challenge for radiotherapy departments [20,24]. Our MR Linac is used for both simulation and treatment delivery, because using the same MR sequence facilitates subsequent co-registration and delineation.…”

“…In addition, in-room MR imaging renders implanted gold markers redundant, thereby avoiding an invasive procedure. Several published papers have described the use of MRgRT [16][17][18][19] in the upper abdominal region, but reports on the use of MRgRT for prostate cancer have been rather of theoretical nature [8,20]. In this study we describe the first clinical implementation of a daily online adaptive MRgRT workflow for SBRT in prostate cancer.…”

Comparative study of algorithms for synthetic CT generation from MRI: Consequences for MRI‐guided radiation planning in the pelvic region

“…However, considering the computation time, DCNN is a more appealing choice for use in the clinic since the synthetic CT generation process takes less 1 min as opposed to atlas‐based methods which take up to 2 hours. This is an important issue in MRI‐guided adaptive RT planning (real‐time adaptive replanning) involving re‐optimization and creation of new treatment plans during RT fractions …”

Clinical relevance of metal artefact reduction in computed tomography (iMAR) in the pelvic and head and neck region: Multi‐institutional contouring study of gross tumour volumes and organs at risk on clinical cases

“…in prostate carcinomas and in some H & N tumours). The phase III prostate advances in comparative evidence (PACE) trial even investigates extreme hypofractionation in prostate cases, using doses of > 7 Gy per fraction . Therefore, high image quality will be of increasing importance as safety margins can be expected to be tight, especially in extreme hypofractionation schedules.…”