A Systematic Review of the Clinical Implementation of Pelvic Magnetic Resonance Imaging (MR)-Only Planning for External Beam Radiation Therapy

Abstract The use of magnetic resonance imaging (MRI) scans alone for radiotherapy treatment planning (MR- onlyplanning) has been highlighted as one method of improving patient outcomes. Recent technological advances have meant that introducing MR- onlyplanning to the clinic is now becoming a reality, with several specialist radiotherapy clinics treating patients with this technique. As such, substantial efforts are being made to introduce this technique into wide-spread clinical implementation. A systematic review of publications investigating the clinical implementation of pelvic MR- onlyradiotherapy treatment planning was undertaken following the PRISMA guidelines. The Medline, Embase, Scopus, Science Direct, CINAHL and Web of Science databases were searched (timespan: all years to 2 nd January 2019). Twenty six articles met the inclusion criteria. The studies were grouped into the following categories: 1. MR acquisition and synthetic-CT generation verification, 2. MR distortion quantification and phantom development, 3. Clinical validation of patient treatment positioning in an MR- onlyworkflow and 4. MR- onlycommissioning processes. Key conclusions from this review are: i) MR- onlyplanning has been clinically implemented for prostate cancer treatments; ii) A substantial amount of work remains to translate MR- onlyplanning into wide spread clinical implementation for all pelvic sites; iii) MR scanner distortions are no longer a barrier to MR- onlyplanning; however they must be managed appropriately; iv) MR- onlybased patient positioning verification shows promise, however limited evidence is reported in the literature and further investigation is required; and v) a number of MR- onlycommissioning processes have been reported which can aid centres as they undertake local commissioning, however this needs to be formalised in guidance from national bodies.