Magnetic resonance‐guided radiation therapy: A review

Abstract

Summary Magnetic resonance‐guided radiation therapy (MRgRT) is a promising approach to improving clinical outcomes for patients treated with radiation therapy. The roles of image guidance, adaptive planning and magnetic resonance imaging in radiation therapy have been increasing over the last two decades. Technical advances have led to the feasible combination of magnetic resonance imaging and radiation therapy technologies, leading to improved soft‐tissue visualisation, assessment of inter‐ and intrafraction motion, motion management, online adaptive radiation therapy and the incorporation of functional information into treatment. MRgRT can potentially transform radiation oncology by improving tumour control and quality of life after radiation therapy and increasing convenience of treatment by shortening treatment courses for patients. Multiple groups have developed clinical implementations of MRgRT predominantly in the abdomen and pelvis, with patients having been treated since 2014. While studies of MRgRT have primarily been dosimetric so far, an increasing number of trials are underway examining the potential clinical benefits of MRgRT, with coordinated efforts to rigorously evaluate the benefits of the promising technology. This review discusses the current implementations, studies, potential benefits and challenges of MRgRT.

Single-Fraction Stereotactic Body Radiation Therapy: A Paradigm During the Coronavirus Disease 2019 (COVID-19) Pandemic and Beyond?

“…Using MRI-guided radiation therapy can alleviate this concern by providing continuous real-time visualization of the target and surrounding organs at risk with no need for implanted fiducial markers and with no added radiation dose to the patient. 122 , 123 Smaller margins and superior soft tissue visualization compared with computed tomography may improve clinical outcomes. Furthermore, the ability of an MR-LINAC to perform daily online adaptive replanning within minutes to account for the current day’s tumor and normal organ anatomy may facilitate safe dose escalation for high-risk targets such as pancreatic 124 and central/ultracentral lung 125 tumors; whether this is feasible in a single fraction remains unclear.…”

Therapeutic Radiographers at the Helm: Moving Towards Radiographer-Led MR-Guided Radiotherapy

“…Magnetic resonance (MR) imaging has the potential to improve focussed radiotherapy delivery because of superior soft tissue contrast over computed tomography (CT)-based technology, and the ability to extract functional information in real time [1]. Hybrid technologies combining linear accelerators (linacs) and MR scanners (MR-linacs) have recently become available commercially and are being implemented both clinically and within a research environment worldwide [2,3]. The MR-linac offers the ability to individualise and adapt daily treatment plans based on the position or anatomy of the day, following either a simple 'virtual couch shift' adapt-to-position (ATP) approach, or a more complex full reoptimisation adapt-to-shape (ATS) method based on the recontouring of relevant structures [4].…”

“…Delivery of a typical adaptive radiotherapy fraction on the MR-linac requires input from various members of the multidisciplinary team; therapeutic radiographers (RTTs), treatment planning physicists or dosimetrists, and clinical/ radiation oncologists [3,5]. Compared with conventional image-guided radiotherapy (IGRT), however, the tasks and responsibilities traditionally associated with these disparate roles are less well defined.…”

Patient-Reported Tolerance of Magnetic Resonance-Guided Radiation Therapy

“…Integrating an MRI scanner into a radiation therapy delivery system enhances the delineation of tumor and organs-at-risk (OAR), accurate patient setup and adaptation of the treatment to interfractional anatomy changes ( 2 , 3 ). MR-guided radiation therapy (MRgRT) also enables monitoring of intrafractional motion and real-time adaptation of the treatment delivery ( 4 – 6 ). Furthermore, utilization of video feedback to patients during the delivery of gated MRgRT allows them to have an active role in their treatment.…”