MRI-Guided Radiotherapy System Types and Magnetic Field Strength

Why Imaging at the Point of Delivery Defines the System Category

Most radiotherapy equipment is described by the beam it delivers, yet the defining feature of this category is the imaging that sits alongside the beam. In an MRI-guided system, a magnetic resonance imaging unit is built into or tightly coupled with the treatment platform, so the imaging used to plan and position treatment can be acquired at the treatment couch rather than in a separate suite.

Across the global MRI-guided radiation therapy systems market, that integration sorts the product landscape before any comparison of software features, because it determines the infrastructure a center must provide and the kind of supplier relationship it enters.

This page describes the five system types and the three magnetic field strength classes tracked in this report as one connected specification. It treats them as market segments only, and it makes no claim about image quality, treatment performance or patient outcome for any system.

System type describes what the platform is: a linear accelerator combined with an MRI unit, a hybrid platform that pairs imaging with another delivery arrangement, a stereotactic system, an adaptive platform or a planning ecosystem. Magnetic field strength describes the magnet class the platform is built around.

The two dimensions are read together because each constrains the other. A magnet class affects the room, the shielding and the service model, while the system type affects which treatment programs the platform is specified for.

Standalone diagnostic MRI scanners and conventional CT-guided linear accelerators sit outside this category, as does particle therapy, since the category is defined by MRI integrated with radiation delivery.

Readers new to the category often start with the delivery unit, but procurement teams tend to start with the room. A vault able to host a magnet and a delivery unit is a larger commitment than a conventional treatment room, which is why this page begins with the combination of system type and field strength rather than with a feature list.

MR-Linac and Hybrid MRI-Radiotherapy Platforms

MRI-guided linear accelerator systems, usually called MR-Linac systems, combine a linear accelerator with an MRI unit in a single platform. They are the first of the five system type categories tracked in this report and the category most closely associated with the term MRI-guided radiotherapy.

Hybrid MRI-radiotherapy platforms form the second category. The term covers platforms that integrate an MRI unit with a radiation delivery arrangement different from the MR-Linac layout, and it is tracked separately because buyers specify the configuration rather than the label.

In both categories the supplier typically provides the magnet, the delivery unit, the control software and the installation as one integrated offering, which is why capital purchases are evaluated at platform level rather than component level.

Platform architecture also determines how upgrades are delivered. Software upgrades can often be added to an installed platform, whereas changes to the magnet or the delivery unit are major projects, so buyers assess a supplier's upgrade roadmap alongside the initial specification.

A further distinction runs between platforms designed around MRI from the outset and arrangements that combine separate imaging and delivery equipment. This report counts a system within the category where the MRI unit is integrated with radiation delivery.

Because the integrated platform is a single product, service responsibility sits with one supplier. Installation and commissioning, preventive maintenance and remote diagnostics are typically contracted together with the platform, and that bundle is part of what a buyer compares between MR-Linac and hybrid offerings.

MRI-Guided Stereotactic Radiotherapy Systems

MRI-guided stereotactic radiotherapy systems are the third system type category. They are platforms specified for stereotactic programs, meaning treatment delivered to a precisely defined target in a small number of sessions, and they combine MRI imaging with the delivery and positioning arrangements such programs require.

Two stereotactic modalities are tracked in this report as market categories. Stereotactic body radiation therapy (SBRT) refers to stereotactic delivery to targets outside the brain, and stereotactic radiosurgery (SRS) refers to stereotactic delivery to intracranial targets.

A buyer evaluating a stereotactic system looks at how the platform handles positioning, imaging at the time of treatment and motion management integration, because those are the capabilities a stereotactic program depends on. This report records them as capability categories and does not compare how any system performs.

Stereotactic systems overlap with the other four types rather than standing apart from them. An MR-Linac can be specified for a stereotactic program, and a stereotactic system can carry adaptive software, so the type label records the primary specification rather than an exclusive capability.

Demand for this category tracks the growth of stereotactic and hypofractionated programs at academic centers, comprehensive cancer centers and specialty radiation oncology clinics, which are the end users most likely to run such programs.

The category also sits next to a separate segment outside this report's scope. Dedicated radiosurgery platforms that do not integrate MRI with delivery are not counted here, because the defining feature of the category is the integrated MRI unit.

Adaptive Radiation Therapy Platforms and MRI-Integrated Planning Ecosystems

Adaptive radiation therapy platforms are defined less by hardware than by the adaptive workflow capabilities layered on top, such as daily replanning, contouring tools and motion management, which this report treats on its own as a technology topic.

As a system type, an adaptive platform is one specified and sold around the ability to revisit a treatment plan at each session using the imaging acquired on the day. The hardware can resemble an MR-Linac or a hybrid platform, but the purchase is justified by the adaptive workflow.

MRI-integrated treatment planning ecosystems are the fifth system type. They cover the planning software, contouring tools and data connections that link MRI imaging to treatment planning and to the oncology information system, and they are often sold as a package alongside the delivery platform.

The two categories matter commercially because they carry the highest software content in the system type dimension. Software is licensed, upgraded and supported on a continuing basis, so these categories behave differently from a one-time hardware sale.

They also create dependencies between suppliers. A center that runs a platform from one supplier and planning software from another must manage integration between the two, and several buyers therefore favor an integrated oncology ecosystem from a single supplier.

Adaptive platforms and planning ecosystems are tracked here as product categories only. This report makes no statement about the planning quality, speed or outcomes that any ecosystem delivers.

Low-Field, Mid-Field and High-Field Systems

Magnetic field strength is the second dimension of this specification and has three categories: low-field, mid-field and high-field MRI-guided systems. Each describes the class of magnet the platform is built around.

Low-field systems are built around lower-strength magnets, high-field systems around stronger magnets of the kind common in diagnostic imaging, and mid-field systems sit in an intermediate range. The class boundaries in this report follow supplier-described categories rather than a single formal definition.

Magnet class is associated with differences in the room a platform needs, the weight and power arrangements, the service model and the way a supplier positions the platform. Those differences shape procurement even when two platforms are otherwise similar.

This report does not compare image quality or treatment performance across magnet classes. Field strength is recorded as a specification category that a buyer or analyst can use to segment the installed and planned base of systems.

Field strength interacts with system type. A given supplier's MR-Linac may be offered in one class only, while a hybrid platform or a planning ecosystem can be associated with more than one, so the two dimensions are best read as a grid rather than as independent lists.

For research purposes the grid is useful because it shows where the category is concentrated and where it is thin. Some combinations of system type and field strength are widely specified, and others are offered by few suppliers or have few installations.

How Field Strength and Platform Type Combine in a Purchase

A purchase specification usually fixes the system type first, since it follows from the treatment programs a center intends to run, and then narrows by field strength, which follows from the building, the budget and the supplier's available configurations.

The sequence differs by organization, and centers that buy these platforms range from academic medical centers with research programs to multi-site oncology networks standardizing across locations, each weighing the same two dimensions differently.

Each of the questions below is answered differently by different buyers, which is why this report segments the category on both dimensions rather than on system type alone.

Three questions recur in buyer evaluations of this category and map directly onto the two dimensions covered here.

• Which system type fits the planned treatment programs, such as stereotactic, hypofractionated or adaptive fractionated delivery?
• Which magnet class can the building, vault and power arrangements accommodate within the project budget?
• How will upgrades, software releases and service be delivered over the life of the platform?