IPEM topical report: guidance on the use of MRI for external beam radiotherapy treatment planning ^*

Abstract

This document gives guidance for multidisciplinary teams within institutions setting up and using an MRI-guided radiotherapy (RT) treatment planning service. It has been written by a multidisciplinary working group from the Institute of Physics and Engineering in Medicine (IPEM). Guidance has come from the experience of the institutions represented in the IPEM working group, in consultation with other institutions, and where appropriate references are given for any relevant legislation, other guidance documentation and information in the literature. Guidance is only given for MRI acquired for external beam RT treatment planning in a CT-based workflow, i.e. when MRI is acquired and registered to CT with the purpose of aiding delineation of target or organ at risk volumes. MRI use for treatment response assessment, MRI-only RT and other RT treatment types such as brachytherapy and gamma radiosurgery are not considered within the scope of this document. The aim was to produce guidance that will be useful for institutions who are setting up and using a dedicated MR scanner for RT (referred to as an MR-sim) and those who will have limited time on an MR scanner potentially managed outside of the RT department, often by radiology. Although not specifically covered in this document, there is an increase in the use of hybrid MRI-linac systems worldwide and brief comments are included to highlight any crossover with the early implementation of this technology. In this document, advice is given on introducing a RT workload onto a non-RT-dedicated MR scanner, as well as planning for installation of an MR scanner dedicated for RT. Next, practical guidance is given on the following, in the context of RT planning: training and education for all staff working in and around an MR scanner; RT patient set-up on an MR scanner; MRI sequence optimisation for RT purposes; commissioning and quality assurance (QA) to be performed on an MR scanner; and MRI to CT registration, including commissioning and QA.

Visualising the urethra for prostate radiotherapy planning

“…17 Recent recommendations that a three-dimensional (3D) isotropic T2-weighted axial acquisition is justified for prostate radiation therapy planning have also been published. 19,20 We verified that an isotropic T2 SPACE (Sampling Perfection with Application optimised Contrasts using different flip angle Evolution) sequence could produce a 3D prostate image of satisfactory quality for clinical use by our GU radiation oncologists (ROs). We found a 0.9 mm isotropic scan provided optimal image quality for multiplane RT planning (Fig.…”

IPEM Topical Report: an international IPEM survey of MRI use for external beam radiotherapy treatment planning

“…Some of the aspects that vary, such as equipment required, MR sequence optimisation, commissioning and QA, and safety features could benefit from guidance from professional bodies. It is known that IPEM has published guidance (Speight et al 2021) and AAPM are working on such guidance, as well as the Nederlandse Commissie voor Stralingsdosimetrie (NCS) who are producing guidelines specifically on MRI QA for RT. Guidance is available for commissioning and QA of MRI scanners for diagnostic purposes (Jackson et al 2010, ACR 2015, McRobbie and Semple 2017, but the requirements for MR for EBRT are different from radiology and hence the QA requirements are different.…”

“…The IPEM working party has addressed some of the issues identified in this work in the form of guidelines for the safe implementation for MR for EBRT (Speight et al 2021).…”

“…There are challenges that must be overcome in order to use MRI in the EBRT treatment planning pathway and understanding these challenges is key to implementing this technology safely. One challenge is that at the time of the survey there was little consensus in the literature or guidance on how to safely implement MRI for EBRT, although this is something that the Institute of Physics and Engineering in Medicine (IPEM) has now published (Speight et al 2021)and the American Association of Medical Physics (AAPM) is aiming to publish on imminently.…”

Magnetic Resonance Imaging Simulation for Anal and Rectal Cancer – Optimising the Patient Experience

“…Within the UK, only 6% of radiotherapy patient treatments used MRI guidance in 2018 and only two radiotherapy centres had dedicated radiotherapy MRI equipment [4]. However, the rationale for the increased use of MRI simulation in radiotherapy is building, through increased evidence of the benefit to patients [5e8], the development of new techniques, such as MRI-only planning [9e11], and recommendations from national bodies on commissioning and use [12,13]. A recent Institute of Physics and Engineering in Medicine (IPEM) international survey of MRI use in radiotherapy showed that a significant number of centres are planning to implement MRI simulation in the next 5 years [3].…”