Overview
The Elekta Unity MR-Linac is not just another radiation machine. It is a fundamentally different way to deliver radiation therapy, one that combines the clarity of high-resolution MRI scanning with the precision of a linear accelerator in the same system at the same time. This helps technologists see the tumor in real time and make adjustments to the treatment plan as and when required.
What is Elekta Unity MR-Linac?
Elekta Unity MR-Linac is a radiotherapy platform. The name comes from the two technologies built into it: MR, which stands for “Magnetic Resonance,” and Linac, which is short for “Linear Accelerator,” the device that delivers the radiation beam.
Most conventional radiation therapy systems use X-ray-based imaging (CT imaging) to position patients and guide treatment. CT imaging is effective, but it has limitations when it comes to soft tissue, like the areas around the pancreas, prostate, or pelvic organs, where subtle shifts can make a real difference to treatment accuracy.
MRI, by contrast, gives a much richer picture of soft tissue. The Elekta Unity combines a 1.5 Tesla MRI scanner with a linear accelerator in a single, integrated system so that imaging and treatment happen together in real time.
How Does MR-Guided Radiotherapy Work?
You will lie on the treatment table and be positioned carefully by your radiation therapy team. Before treatment begins, the system takes an MRI scan, which your oncologist reviews on screen. If the tumor or surrounding organs have shifted since your last visit (which is common, especially with organs that move due to breathing or digestion), the treatment plan is adjusted to reflect what is actually seen that day. This is called online adaptive radiotherapy.
The radiation beam is then delivered continuously from 360 degrees around your body. The MRI continues to monitor your anatomy throughout the session. If the system detects movement, the team can pause, adapt, and resume so that the dose goes precisely where it is intended and not into surrounding healthy tissue.
For patients, this process is not painful, and there is no sensation from the radiation itself. The experience is similar to lying in an MRI scanner, which produces a soft humming or clicking noise during imaging.
Key Features of Elekta Unity MR-Linac
A few things set the Elekta Unity apart from conventional radiation therapy systems.
- 1.5 Tesla MRI imaging: This is the same strength of MRI used for diagnostic scans in major hospitals. It provides clear, high-resolution images of soft tissue, including structures that are difficult to see on CT, like the prostate's internal anatomy, small lymph nodes, or tumors near the pancreas.
- Real-time visualization: The system can acquire MRI images during the treatment session itself, giving your team a live view of tumor position as radiation is being delivered.
- Online adaptive planning: Your care team can adjust the radiation plan before each fraction (each treatment session) based on what the MRI shows that day.
- Biology-guided Radiation Therapy (BgRT): Elekta Unity also serves as a platform for emerging BgRT techniques, where biological characteristics of the tumor, not just its physical shape, can inform how radiation is delivered. This is an area of active clinical research.
- Comprehensive Motion Management: A dedicated system to account for tumor movement caused by breathing, digestion, or other bodily processes, so that the beam follows the target throughout delivery.
What is Online Adaptive Radiotherapy?
In conventional radiation therapy, a plan is made once, at the beginning of treatment, based on a CT or MRI scan taken during simulation. That plan is then repeated, session after session, over several weeks. The assumption is that the tumor stays in roughly the same place and that surrounding anatomy does not shift significantly. That assumption, unfortunately, is not always correct.
During treatment, tumors can shrink, the bladder fills and empties, the bowel moves, and body weight changes. All of these things affect where exactly the tumor sits on any given day.
Online adaptive radiotherapy means the treatment plan is reviewed and, if needed, modified at each session, based on a fresh MRI taken that same day. Your radiation oncologist and their team assess the updated images, check whether the original plan still delivers the dose accurately, and if not, generate a new optimized plan before treatment starts. On the Elekta Unity, this entire process takes place within the same treatment session, without the patient having to leave the table.
It takes longer per session than conventional radiotherapy. But for certain tumor types and locations, the clinical benefit of that additional care can be significant.
Comprehensive Motion Management
When you breathe, the structures in your chest and abdomen shift, sometimes by a centimeter or more. Your diaphragm moves, and so does your liver, your pancreas, your lungs, and the lymph nodes near them. A bowel full of gas today may be empty tomorrow. These are not unusual situations. They are daily realities for almost every patient undergoing radiation treatment.
Traditionally, radiation oncologists have managed these challenges by expanding the treatment area to account for expected movement, a margin that essentially says, “the tumor might be anywhere in this zone, so we will cover the whole zone." That approach works, but it also means more healthy tissue receives radiation than strictly necessary.
The Elekta Unity's Comprehensive Motion Management system is designed to reduce that uncertainty. Using continuous MRI during treatment, the system tracks the position of the tumor as you breathe, and the care team can choose the motion management strategy that best fits your situation. In some cases, this allows margins to be reduced, which in turn can reduce the dose to surrounding organs.
Clinical Indications for Elekta Unity MR-Linac
The Elekta Unity MR-Linac is suitable for a wide range of cancers, particularly those located in or near soft tissue structures that are difficult to visualize on CT alone. It is especially well-studied for:
- Prostate cancer: MRI offers excellent soft tissue detail in the pelvic region, making it possible to visualize the prostate, the urethra, and the neurovascular bundle. The platform also facilitates ultra-hypofractionated treatment, which involves delivering a full course in as few as two to five sessions.
- Pancreatic cancer: Treating the pancreas has always been technically demanding because of its location near critical structures and its tendency to move with breathing. The Elekta Unity's real-time MRI and motion management make it possible to deliver a precise dose to pancreatic tumors with greater confidence.
- Liver cancer: The liver moves considerably with respiration. Fiducial-free liver SBRT, a form of high-dose, short-course treatment without the need to implant small marker seeds in the liver, can be performed on the Elekta Unity platform.
- Rectal cancer: Pre-operative and definitive radiation for rectal cancer is an established application. Daily adaptive planning allows the treatment to account for variation in bowel filling and tumor response over the course of treatment.
- Head and neck cancers: Tumor shrinkage and weight loss during treatment are common in head and neck cancer. Adaptive radiotherapy allows the plan to respond to these changes, potentially improving the protection of salivary glands and other structures.
- Oligometastatic disease: Patients with a limited number of metastases (spread to sites such as lymph nodes, spine, or adrenal glands) may be candidates for ablative radiotherapy on the Elekta Unity.
- Kidney and gynecological cancers: These are among several additional indications that are supported by growing clinical evidence.
Your oncologist will advise whether Elekta Unity treatment is appropriate for your specific diagnosis and stage.
Elekta Unity vs. Conventional Linear Accelerator: A Comparison
It helps to understand how the Unity differs from a standard radiation therapy machine, particularly if you have had treatment before or are comparing options.
| Feature | Conventional Linac | Elekta Unity MR-Linac |
|---|---|---|
| Imaging type | X-ray-based CT imaging | 1.5 Tesla MRI (superior soft tissue detail) |
| Imaging timing | Before treatment (offline) | Real-time, during every session |
| Plan adaptation | Fixed plan, rarely updated | Online adaptive - updated each session if needed |
| Motion management | Fixed margins to account for movement | Real-time tracking; margin reduction possible |
| Tumor visibility | Limited for soft tissue structures | High-resolution soft tissue visualization |
| Treatment fractions | Standard or moderate hypofractionation | Enables ultra-hypofractionation for some cancers |
| Session duration | Typically 10 to 20 minutes | Longer per session: 30 to 60 minutes depending on adaptation needed |
The longer session time on the Elekta Unity is worth noting. For some patients, this can be physically demanding, and your team will discuss comfort positioning and any support needed. That said, many patients also complete their course in fewer total sessions than with conventional treatment, which reduces the overall number of hospital visits.
Undergoing Radiation Therapy on Elekta Unity MR-Linac Platform at HCG
Radiation therapy has advanced considerably over the past two decades, but the ability to see the tumor clearly while delivering treatment and to adapt the plan in real time represents a meaningful step forward. That is what the Elekta Unity MR-Linac makes possible.
At HCG Cancer Hospital, our radiation oncology team has trained extensively with this technology. We work closely with medical physicists, radiation therapists, and a multidisciplinary tumor board to ensure that every patient treated on the Elekta Unity receives a plan that is both precise and appropriate to their individual situation.
