Introducing the MRIdian – an evidence-based treatment for prostate cancer

Treating prostate cancer with radiotherapy can be difficult due to the naturally occurring movement of the surrounding internal organs. Until now, conventional linacs have had to rely on computer tomography (CT) scans to define the treatment area. However, this can cause uncertainty and inaccuracy when delivering radiotherapy due to the large planning target volume margins required.

The MRIdian MR linac makes it possible to deliver magnetic resonance image guided radiotherapy (MRIgRT) in a way that targets tumour sites in real-time and is supported by a wealth of clinical research.

A recent Phase III randomised clinical trial demonstrated that using MRI guidance to deliver 5# stereotactic ablative radiotherapy (SABR) to patients with localised prostate cancer reduced levels of genitourinary and gastrointestinal toxicity1. This, in part, is thanks to the MRIdian’s unique facility for ‘automated beam gating’ – a state-of-the-art system that only delivers the radiotherapy dose when the tumour is positioned inside the treatment boundaries.

We're proud to be the first independent healthcare provider to introduce the first two MR linacs of this kind to the UK market. So far, we have treated more than 830* patients using these world-class radiotherapy systems at our centres in Oxford and Cromwell Hospital London. 

An additional MRIdian will also be accessible in our state-of-the-art centre currently under construction in Guildford, opening in December 2023.

*Figure accurate as of February 2023

An efficient radiotherapy solution

Adaptive radiotherapy offers added confidence to SABR delivery

MRIgRT is one of the biggest and most exciting developments to happen in advanced radiotherapy in recent years. 

By combining a linear accelerator with a high-definition MRI scanner, MRIdian makes truly adaptive SABR delivery possible for the first time, allowing clinicians to actively visualise the treatment area and feel more confident when delivering treatments.

MRIdian also greatly improves on conventional image-guided radiotherapy, in that it allows tracking of the target position in real time and offers millimetric levels of accuracy. These attributes open multiple new avenues of delivering high doses of radiation to transitional tumour sites within close proximity of organs at risk. 

Recently, there has also been a growing body of evidence to support 5# SABR delivered on the MRIdian for patients with low to intermediate-risk and selected high-risk localised prostate cancer. This can provide a variety of additional benefits to patients. 

Benefits for patients with prostate cancer

A non-surgical alternative

MRI-guided 5# SABR for prostate cancer is a less invasive, non-surgical treatment that can reduce patient waiting times and hospital stays. 

Reduced toxicity levels

Patients treated with MRI-guided 5# SABR show reduced gastrointestinal and genitourinary side effects when compared to moderate hypofractionation1. 

Fewer treatment sessions

A reduced number of treatment sessions leads to fewer and less severe side effects and less interruption in the patient's daily life. 

Prostate patient eligibility

What are the inclusion criteria?

  • Aged 18 years or older
  • WHO performance score 0-2 or Karnofsky performance status 70-100%
  • Biopsy proven adenocarcinoma of the prostate
  • Gleason ≥ 6
  • Prostate volume ≤ 90 cc on transrectal ultrasound (TRUS)
  • International Prostate Symptoms Score (IPSS) ≤19
  • T-stage: T1c-T3b (on MRI and/or endorectal ultrasound)
  • No evidence of lymph node or distant metastases on radiological staging
  • All patients should be able to undergo MRI scans
  • Reviewed by a multidisciplinary team and external beam radiotherapy is an option for treatment
  • Previous TURP is allowed provided there is at least eight weeks’ interval with radiotherapy
  • The administration of concomitant hormonal therapy is allowed

What are the exclusion criteria?

  • Previous irradiation in the pelvic region
  • Contraindications for MRI
  • Patients who have electronic devices such as pacemakers or implanted defibrillators, deep brain stimulators, cochlear implants
  • Patients who have a metallic foreign body in their eye
  • Patients who have an aneurysm clip in their brain
  • Patients with severe claustrophobia may not be able to tolerate an MRI scan
  • Patients with inflammatory bowel disease

What information is required to refer a patient for prostate radiotherapy on the MRIdian?

The minimum data set is:

  • Prostate radiotherapy consent form
  • MR-linac supplementary consent form
  • Booking form (electronic/paper)
  • Referral letter (letter referring the patient to the clinical oncologist)
  • Histology report
  • Prostate MRI report and images if possible
  • GenesisCare MRIdian assessment pro forma
  • Please note, on occasions some insurers may ask for a medical report.

Evidence base

There has been an increasing international evidence base for using 5# SABR, MR-linacs, and the MRIdian system specifically to treat prostate cancer.

Here are some of the key pieces of research to have been published over recent years.

Patient case studies

Having treated more than 830* patients with prostate cancer using MRI-guided SABR, our specialist team has significant first-hand experience of witnessing how impactful MRIdian can be.

Listed below are some of our most noteworthy patient case studies.

*Figure accurate as of February 2023

Discover more about our patient case studies.

MRIdian specialists at GenesisCare

Patient care on the MRIdian is delivered by a team of specially trained consultant oncologists, selected based on their clinical expertise. The team collectively provide a comprehensive infrastructure for patient selection, peer review and clinical governance for all referrals as well as the credentialing of new clinicians in MRI-guided radiotherapy. 

Urology SABR Advisor Team

Our SABR service is spearheaded by the Urology SABR Advisor Team – a group comprised of leading oncologists that specialise in urology. The role of this group is to review all referrals to the GenesisCare service for urological cancers such as prostate cancer, improve patient access to SABR treatments, and contribute to the existing evidence base.

Discover more about our specialist teams here.


  1. Kishan A, Martin T, Lamb J, Casado M, et al. (2023). Magnetic Resonance Imaging–Guided vs Computed Tomography–Guided Stereotactic Body Radiotherapy for Prostate Cancer: The MIRAGE Randomized Clinical Trial. JAMA Oncol. e226558. doi: 10.1001/jamaoncol.2022.6558.
  2. Bruynzeel A, Tetar S, Oei S, Senan S, et al. (2019). A Prospective Single-Arm Phase 2 Study of Stereotactic Magnetic Resonance Guided Adaptive Radiation Therapy for Prostate Cancer: Early Toxicity Results. Int J Radiat Oncol Biol Phys. 105(5): 1086-1094.
  3. Tree A, Ostler P, van der Voet H, Chu W, et al. (2022).  Intensity-modulated radiotherapy versus stereotactic body radiotherapy for prostate cancer (PACE-B): 2-year toxicity results from an open-label, randomised, phase 3, non-inferiority trial. Lancet Oncol. 23(10): 1308-1320.
  4. Spittle, M (1978). Methotrexate and Radiation. Int J Radiat Oncol Biol Phys. 4(1-2): 103-7.