Download MRIdian™ system for MRI-guided radiotherapy

Health Policy Advisory Committee on
Technology
Technology Brief
MRIdian™ system for MRI-guided radiotherapy
July 2015
© State of Queensland (Queensland Department of Health) 2015
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This brief was prepared by Mr Nicholas Marlow from ASERNIP-S.
Summary of findings
The MRIdian system incorporates two existing technologies (MRI and cobalt radiotherapy)
into one cohesive unit, bringing significant potential advantages, however, the efficacy and
safety of combining these two technologies into a single unit are yet to be established. The
few studies available (one level III-3 study and a series of conference abstracts) only report
technical aspects of MRIdian’s treatment planning system. The safety and effectiveness and
safety of the MRIdian system has not been reported, and there are no ongoing clinical trials
of the technology. However, as the MRIdian system represents convergence of two well
known existing, and validated technologies, it is understandable that clinical trials
specifically investigating this technology may not be forthcoming.
This technology is more about doing radiotherapy better rather than doing it more
efficiently. For example, it has the potential to really improve the quality of some
treatments with its real-time tracking and image capabilities, but this is highly tumour
stream-dependent.
Further studies are required that report on the efficacy and safety of the associated
treatment planning software, since this could have a significant impact on the accuracy of
the calculated dose compared to the actual delivered dose. The possible limitations of a Co60 based treatment device compared to traditional linear accelerator-based radiotherapy
are not defined (e.g. length of treatment times) and the image guidance potential based on
MRI, and the use of this for radiotherapy field positioning intervention in comparison to
existing kV image guidance, are yet to be established.
The concurrent development and commercialisation of MRI/linear accelerator-based
radiotherapy technology is likely to compete with the MRIdian system, which funders and
providers will have to consider.
HealthPACT Advice
Although the MRIdian system may potentially offer some benefits for treating some tumour
types, there is currently no evidence of any incremental clinical or cost effectiveness over
existing radiotherapy modalities. Therefore, HealthPACT does not support investment of
this technology by, nor its introduction into, clinical practice at this time.
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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Technology, Company and Licensing
Register ID
WP214
Technology name
MRIdian™ system
Patient indication
Patients with soft tissue lesions and tumours. In particular,
patients with tumours that are likely to move, change shape
or size through treatment, or are located in close proximity to
organs that are likely to move during radiation treatment.
Description of the technology
Radiation therapy is one of the primary modalities used to treat cancer. It involves
identifying cancerous tissue and irradiating it with high-energy particle beams, thereby
killing the cancer cells by damaging their DNA. Care has to be taken to spare the healthy
tissue surrounding the tumour.
Radiation can be delivered in the following ways for localised treatment:
1) Placing sealed-source radioactive material in the body near the cancer cells
(brachytherapy);
2) Applying external beams of radiation using a machine (external beam radiation
therapy).
In addition, for disseminated disease, unsealed radioactive materials may be administered
systemically either orally or by injection (therapeutic nuclear medicine).
External beam radiation therapy (EBRT) is the most widely used modality and is most
commonly delivered using a high-energy (megavoltage, MV) X-ray machine, called a linear
accelerator (LINAC), to direct radiation to the tumour. There are many terms used for
different types of EBRT of varying complexity including 3D conformal radiation therapy
(3DCRT), intensity-modulated radiation therapy (IMRT), volumetrically modulated arc
therapy (VMAT), tomotherapy, stereotactic radiotherapy (SRT), image-guided radiation
therapy (IGRT), 4D-radiotherapy, radiosurgery, stereotactic ablative body radiotherapy
(SABR, or SBRT).1 The EBRT used by the MRIdian system is technically delivered from a MRI
cobalt machine.
A treatment plan is developed, optimised, verified and approved for each patient
undergoing external beam radiation therapy by a multi-disciplinary team (including
radiation therapists, radiation oncology medical physicists and radiation oncologists, under
the responsibility of a lead radiation oncologist) in a process called simulation and
treatment planning. Simulation involves taking detailed scans of the patient’s tumour and of
the surrounding normal tissue, on a CT-simulator. These may be supplemented by
registering and fusing additional images from magnetic resonance imaging (MRI), positron
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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emission tomography (PET) or ultrasound to provide complementary imaging that can
better help define target volumes.
After simulation the radiation oncologist determines the exact treatment volume and the
relevant normal tissue organs at risk nearby, across all scans, and defines the dose
prescription. The latter includes the total radiation dose to be delivered to the tumour; a set
of dose-volume requirements for the dose distribution to target volume; and, dose-volume
constraints to the organs at risk, (including the maximum radiation dose allowable for
normal tissues around the tumour, and the safest paths for radiation delivery). A specific
technical treatment plan is then developed by a radiation therapist, to optimise the
radiation delivery to as close as possible to the set of prescription requirements. Plans are
checked, often directly dosimetrically verified. Once approved by the radiation oncologist,
plans are transferred to the treatment unit for radiation therapy to commence.1
The type of cancer being treated, the complexity of tumour and organs-at risk anatomy and
the clinical dosimetry requirements determine the complexity of external beam radiation
used. IGRT is especially useful for cancers located in parts of the body prone to movement,
such as the lungs and liver, and for sites near major organs and tissues that should not
receive radiation.2 IGRT is used or for detecting changes during treatment to enable ongoing
treatment modifications (‘adaptive radiotherapy’, ART). In IGRT, the imaging equipment
(megavoltage or kilovoltage X-ray, cone-beam CT (CBCT), MRI or ultrasound) is available in
the treatment room, often mounted on, or built into, the machine that delivers the
radiation. This allows the radiation oncology team to scan the tumour and the nearby
normal tissue organs at risk immediately before, and even at intervals within the radiation
treatment. Specialised software then compares these images to the reference images taken
during simulation. Any necessary adjustments are then made to the patient's position and
to the radiation beam targeting to more precisely direct radiation at the tumour, enabling
treatment margins to be reduced, and minimising irradiation of the surrounding healthy
tissue.2 This in turn reduces unwanted side effects (toxicity) or allows dose escalation to the
target volume for better tumour control whilst keeping the toxicity the same.
IGRT systems can be used for verifying and correcting patient position and radiation beam
positioning. The more advanced IGRT systems, e.g. CBCT, can be used in adaptive
radiotherapy and re-planning and in motion management for moving targets (using
developmental gating and tracking methods).The MRIdian System is a new type of IGRT that
combines MRI with a radiation delivery system in a single unit, using cobalt-60 radioactive
sources to produce the external radiation beams. It is currently the only commercially
available system to do so. The system is designed so that the imaging and radiotherapy
fields are synchronised, permitting imaging of the irradiated tissue both before and
continuously throughout treatment.3 The MRI component of the MRIdian System has three
different functions:
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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1) treatment planning—the images can be used in pre- and intra-treatment planning;
2) patient positioning—the images can be used to guide patient position during
treatment; and
3) treatment gating (soft-tissue tracking)—images can be taken continuously during
therapy to control the radiation beam based on anatomic motion.3
The MRIdian system is the first to enable continuous imaging of soft tissues throughout the
entire radiation treatment session. This means that adjustments can be made for tumour
movement in real time. If a tumour moves beyond a defined boundary, as a result of
breathing or other movement, the radiation beam automatically pauses. When the tumour
moves back into the target zone, treatment resumes. This minimises unintended irradiation
of healthy surrounding tissue. Clinicians can allow for the motion of a patient’s organs by
setting both space and time thresholds for pausing treatment delivery.4, 5 This can be done
on some x-ray IG systems, but with much less detail of the soft tissues and often requiring
implantation of metal seeds into the tumour to allow its motion to be visualised.
Figure 1
MRIdian system
The main purported advantages of the MRIdian system are that it:
provides better soft-tissue contrast than x-ray imaging systems, giving the clinician a
clearer view of the patient’s internal organs during treatment;
does not expose patients to additional radiation, unlike CT-based IGRT;
more easily enables adjustments to be made for tumour movement in real time;
does not require implanted or external reference-point markers for targeting.5
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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To achieve these advantages, however, it uses Co-60 as the radiation beam source. This has
some potential disadvantages: of radiation beam energy (penetration and dose
distribution), penumbra (‘fuzziness’ of the beam edge), dose rate, and the need to regularly
change the radioactive sources.
Company or developer
ViewRay Inc., Ohio, United States of America.
Reason for assessment
The nominated system purports to enable real-time viewing of the patient anatomy during
the radiation therapy process thereby enabling enhanced responsiveness to adaptive
treatment changes and improved patient outcomes.
Stage of development in Australia
Yet to emerge
Established
Experimental
Established but changed indication
or modification of technique
Should be taken out of use
Investigational
Nearly established
Licensing, reimbursement and other approval
The MRIdian system has received 510(k) clearance from the United States Food and Drug
Administration (FDA) and the CE mark.6 It has not been approved by the Australian
Therapeutic Goods Administration.
Australian Therapeutic Goods Administration approval
Yes
ARTG number (s)
No
Not applicable
Technology type
Device
Technology use
Therapeutic
Patient Indication and Setting
Disease description and associated mortality and morbidity
Cancer is a disease that occurs when abnormal cells grow in an uncontrolled way. These
abnormal cells can damage or invade surrounding tissue, or spread to other parts of the
body, causing further damage. Most cancers start in a particular organ, which is then called
the primary site or primary tumor. There are many different types of cancer, and usually
they are named after the organ or cell type of the primary cancer.7
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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Cancer is the leading cause of disease burden and injury in Australia, accounting for
approximately 19 per cent of the total burden of disease in 2010. At current incidence rates,
one in three men and one in four women in Australia will be diagnosed with cancer by 75
years of age.8 The Australian Institute of Health and Welfare (AIHW) estimated that about
128,290 Australians would be diagnosed with cancer (72,110 men and 56,180 women) in
2014. Of these, the most commonly reported are expected to be prostate cancer, followed
by bowel cancer, breast cancer, melanoma of the skin and lung cancer.9 An estimated
149,990 people are expected to be diagnosed in 2020. Between 1982 and 2014 the number
of new cancer cases diagnosed more than doubled from 47,417 to 123,920.10
It was estimated by the AIHW that nearly 45,780 Australians would die from cancer in 2014;
accounting for three in 10 deaths. For all cancers combined, the age-standardised mortality
rate is estimated to have decreased by 20 per cent, from 209 per 100,000 in 1982 to 168 per
100,000 in 2014.9
Cancer is also a major cause of hospitalisation in New Zealand and a leading cause of
morbidity and mortality, accounting for nearly one third of all deaths (28.9%). In 2010,
21,235 people were diagnosed with cancer in New Zealand and 8,593 people died from the
disease. In that year, prostate cancer and bowel cancer were the most commonly diagnosed
cancers (2,988 registrations for each cancer), followed by breast cancer and melanoma.
Lung cancer was the leading cause of cancer-related death, followed by cancer of the bowel,
breast and prostate.11 The total number of cancer registrations in New Zealand is projected
to increase by approximately 30 per cent between 2012 and 2022.12
Number of patients
According to the AIHW procedural data cubes, 7,825 radiation procedures of relevance to
this technical brief were performed in 2012–2013 (procedure numbers 15239-00, 15254-00,
15269-00, 15600-00, 15600-01 and 15600-03). No similar data for New Zealand was readily
available.
Speciality
Oncology and Radiotherapy
Technology setting
General Hospital, Specialist Hospital
Impact
The MRIdian System is a substitution technology. Given that it combines an image guidance
system and a radiation therapy delivery system (Co-60) in the one device, it is expected to
directly replace existing machines that have an x-ray IGRT imaging system and LINAC-based
radiotherapy delivery system. If MRI-based simulation and planning becomes more widely
accepted, it could potentially replace current imaging technology used to develop a
patient’s treatment plan as well as technology used to deliver radiation therapy.
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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Current technology
There are several types of IGRT used to deliver external beam radiation. Almost all LINACs
since the late 1980s have been equipped with electronic portal imaging devices (EPIDs),
which directly image using the (MV) treatment beams, and which replaced the use of port
films. Since the mid-2000s, most new LINACs have been supplied with add-on low-energy
(kilovoltage, kV) x-ray sources and solid state imaging panels that allow kV images and kV
cone-beam CT scanning for IGRT. All modern radiotherapy uses EPIDs at least for image
guidance of patient set up and most advanced and complex radiotherapy techniques (eg
IMRT, VMAT, SRS, SBRT) require at least one or other of the more sophisticated IGRT
systems (eg kV or MV CBCT).
Diffusion of technology in Australia
The MRIdian System is not currently used in Australia. A position paper on techniques and
technologies in radiation therapy produced by the Royal Australian and New Zealand
College of Radiologists in 2013, states that the IGRT is essential (‘clinically indicated’), must
be available in every department and is an essential component for IMRT. The document
noted that at that point MRI-guided IGRT was in development, mentions its advantages and
states that uptake in Australia and New Zealand was ‘will depend on further development,
research and the production of more advanced MRI-LINAC modles’13
International utilisation
Country
Level of Use
Trials underway or
completed
Limited use
United States of America

Italy

Widely diffused
Cost infrastructure and economic consequences
The MRIdian system comprises a split magnet MRI system, with a low field magnet (field
strength 0.35T), a rotating gantry assembly, with 3 Co-60 sources at 120 degree intervals, a
patient couch, various control consoles, an on-board ‘Monte Carlo’-based adaptive
treatment planning system (TPS) and IMRT capability. 14 The System costs about USD 8.5
million, with vault construction to house the system potentially costing an additional USD
1.5 million.15
Adaptive radiation therapy, with immediate re-planning requires fast and accurate image
registration and manipulation and then rapid planning for a smooth efficient adaptive
workflow. The company states that a full treatment plan using MRIdian can be done in
under two minutes, compared with 15 to 20 minutes for most other Monte Carlo-based
systems.4
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Ethical, cultural, access or religious considerations
No cultural, religious, or access considerations for the MRIdian system were identified.
Evidence and Policy
Safety and effectiveness
One non-randomised comparative study (level III interventional evidence) and five
conference abstracts of case series studies (level IV interventional evidence) were identified
for inclusion in this report. However, all but one of these studies assessed only technical
aspects of the treatment planning capabilities of the MRIdian system and typically planning
on CT image data sets, not on MRI image datasets. Patient outcomes related to the
radiotherapy treatment were not reported in any study.
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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Table 1
Included study characteristics
Study / Design
Saenz et al 2014
16
III-3
USA
Wooten et al 2014
17
III-3
USA
Parikh et al 2014
18
III-3
USA
Olsen et al 2014
19
IV
Inclusion criteria
Number of patients
Patients who received
previous radiation
therapy; head and
neck, lung and
prostate
N=14 treatment
planned with both
MRIdian and Pinnacle
system
Patients who had
previously received
treatment with linear
accelerators
N=10
Patients undergoing
image-guided
radiation therapy for
cancer in the
abdomen, head/neck,
thorax and pelvis
N=14
Patients undergoing
radiation therapy
N=19
NR
N=5
USA
20
Mutic et al 2014
IV
USA
21
Noel et al 2012
IV
USA ca
NR
Conflicts of interest
NR
Losses to follow-up =
NR
Losses to follow-up =
NR
Losses to follow-up =
NR
Losses to follow-up =
NR
Honoraria, travel
expenses, advisory
board, employee stock
options reported amongst
authors
Research Grant from
MRIdian
One author has stock
options with MRIdian,
another has received a
research grant from
MRIdian
Losses to follow-up =
1
Honoraria, travel
expenses, research
grants, stock options and
employee of MRIdian
were reported for several
authors
N=5
NR
Losses to follow-up =
NR
Saenz et al 201416
Saenz et al 2014 compared the homogeneity index (HI) and conformity index (CI) scores of
treatment plans and the volume of tissue receiving 20 per cent of the prescribed dose for
the MRIdian planning system and Co-60 beams to those planned in the Pinnacle TPS for a
6MV LINAC. TPS versions were: MRIdian system, version 3.4.0.2, and Pinnacle version 9
(Pinnacle Systems, Inc., California, USA). The HI is a measure for uniformity of dose
distribution over the target volume, while CI indicates how well the distribution of radiation
conforms to the shape of the target tissue.
Planning objectives and treatment planning information including CT images, structure sets,
and points of reference, were exported from the Pinnacle system into the MRIdian system.
Two approaches using the MRIdian system were examined: ‘A’ used the same number of
beams as the Pinnacle plan (number of beams not reported), and ‘B ‘used 54 beams as an
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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extreme test. Data from 14 patients receiving radiotherapy treatment in the head and neck
(n=6), lung (n=4) and prostate (n=4) were analysed with both software systems.
Effectiveness
The MRIdian HI score increased (ie worse homogeneity) for each of the three target areas in
comparison to the Pinnacle score for all approaches except for two 54-beam plans. The
head and neck group showed the lowest HI score increase (1-4 per cent), compared with 1-7
per cent for the lung, and 3-11 per cent for the prostate. Overall, the MRIdian treatment
plans were stated to be comparable with the Pinnacle plans and had good radiation dose
delivery for head and neck tumours. Varied results were identified in the CI comparison
between MRIdian and Pinnacle treatment plans. The CI for the head and neck tumour group
decreased by 22 per cent (worse conformity). CI scores for the lung treatment group
showed a modest improvement (4%) with MRIdian, compared with the Pinnacle plan,
whereas results from the three prostate cancer plans were inconclusive. These are
compatible with expectations from using Co-60, compared to 6MV, taking into account the
beam characteristics (personal communication).
Safety
It was identified that management was required to mitigate MRIdian system skin hot-spots,
particularly for prostate treatments. One example of a hot-spot was noted of around 10%
greater than for the 6 MV plan.
Wooten et al 201417
Wooten et al 2014 reported on the treatment planning capabilities of the MRIdian for 10
selected patients with cancers in the head and neck (n=2), thorax (n=2), breast (n=2),
abdomen (n=1), bladder (n=1) and prostate (n=2), who had previously received radiation
treatment with LINAC. The same CT datasets from the previous therapy were used to create
the plans with MRIdian. For all cases, the mean doses to relevant organs at risk (OAR), target
coverage and target homogeneity were compared between the MRIdian and LINAC plans.
Effectiveness
For patients with head and neck, breast, thorax and bladder cancers, only minor differences
in mean dose were observed between the MRIdian and LINAC plans for OAR (parotids,
larynx, lungs, heart and rectum). The MRIdian plans were generally similar to the LINAC
plans, but the LINAC plans offered better OAR-sparing in some individual cases.
Safety
No safety outcomes were reported.
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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Parikh et al 201418
A conference abstract by Parikh et al 2014 reported on the comparative visualisation of
patient anatomy using the MRIdian system versus cone-beam computed tomography
(CBCT)/megavoltage computed tomography (MVCT). Fourteen patients undergoing IGRT for
cancer in the abdomen (n=3), head/neck (n=3), thorax (n=2) and pelvis (n=6) were enrolled.
CBCT/MVCT image sets used for routine treatment localisation were collected for each
patient within two weeks of MRIdian MRI. Both images sets were displayed sided-by-side on
image-viewing software and were independently reviewed by three radiation oncologists.
Each physician was asked to evaluate which image set offered better visualisation of the
target and OARS.
Effectiveness
Fifteen to 24 OARS were evaluated per anatomical site (abdomen, n=15; head/neck, thorax
and pelvis, n=24). A total of 234 OARs and 10 unique target structures were compared by
each physician. At least two of the three physicians reported that MRI offered better
visualisation for 71 per cent of the structures. CBCT offered better visualisation in nine per
cent of the structures and equivalent visualisation to MRI for 19 per cent of structures. For
74 per cent of the structures analysed, the physicians agreed unanimously on which image
set offered the best visualisation. There was agreement between two of the three
physicians for 99 per cent of the structures evaluated. For one per cent no consensus was
reached. Structures that were better visualised by MRI 100 per cent of the time included the
anal canal, bladder, blood vessels, brachial plexus, brain, colon, duodenum, oesophagus,
most heart structures, kidneys, liver, optic chiasm and nerve, parotids, penile bulb, prostate,
rectum, seminal vesicles, small bowel, spleen, stomach, submandibular glands, spinal cord,
uterus and vagina.
Safety
No safety outcomes were reported.
Olsen et al 201419
A conference abstract by Olsen et al 2014 reported on the feasibility of visualising radiation
targets and OAR with cine MRI using the MRIdian system in 19 patients undergoing
radiation therapy. A total of 35 cine image sets were taken. Three radiation oncologists
evaluated all radiation therapy targets and OAR within the imaging field of view for each
dataset. Physicians were asked if the image quality was suitable for the purpose of
treatment gating (soft-tissue tracking).
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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Effectiveness
A total of 21 target structures and 321 OAR were evaluated in 35 image sets. This included
13 unique targets and 58 unique OAR. All three physicians agreed that image quality was
suitable for manual gating or tracking in 54 per cent (7/13) of the targets and 76 per cent
(44/58) of the OAR. Unanimous consensus was reached for 90 per cent (19/21) of targets
and 96 per cent (308/321) of critical structures evaluated. Targets which were well
visualised included tumours of the: cervix, liver, lungs, nasopharynx and breast lumpectomy
cavity. OAR that were well visualised included the aorta, heart, tongue, bladder, brain,
breast, lung structures and vessels, intestine, oesophagus, femur, kidney, larynx, liver, eye
structures, pelvic bones and vessels, penis and prostate, rectum, rib, sacrum, spinal cord,
spleen, stomach, trachea, uterus and vertebral body.
Safety
No safety outcomes were reported.
Mutic et al 201420
Mutic et al 2014 evaluated the first five patients from a registry designed to monitor the
MRIdian system. Those on the registry included a patient with colon cancer invading the
abdominal wall, a patient with an unresectable intra-abdominal desmoid tumour, a patient
with a fourth lung cancer over a 14 year interval, a patient with lung cancer iliac metastasis,
and a patient with isolated, nodal breast cancer recurrence at the aortic arch with prior
chest wall radiation therapy. One patient was unable to complete treatment due to medical
reasons and was excluded from the analysis. All cases were evaluated for any additional
findings on daily MRI, localisation ability based on MRI, and the degree of tumour and
surrounding anatomy motion.
Effectiveness
Patient outcomes regarding radiation therapy with MRIdian were not reported. Additional
bone metastases were found with MRIdian that were not visible on planning CT scans.
Physicians reported that tumours were easily located using MRIdian.
Safety
No safety outcomes were reported.
Noel et al 201221
The conference abstract by Noel et al 2012 investigated the feasibility of using the MRIdian
system to track bowel movement in real time during radiation therapy for abdominal
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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cancer. The study assessed two bowel-tracking algorithms, a normalised cross-correlation
(NCC) and a weighted NCC (WNCC), in five patients.
Effectiveness
Both algorithms successfully tracked 31 of 32 cine MRI sets (movie-like MRI images) in 100
per cent of the frames. The WNCC algorithm was faster than the NCC algorithm and
captured a greater range of motion in all cases.
Safety
No safety outcomes were reported.
Economic evaluation
No economic evaluation of the MRIdian system was identified.
Ongoing research
A search of clinicaltrials.gov and the Australian New Zealand Clinical Trials Registry did not
identify any clinical trials on the MRIdian system.
Other issues
There are a number of research programs developing MRI-LINAC systems for MRI imageguided RT, eg the pioneering work in Utrecht, the Netherlands (in collaboration now with
Elekta and Philips), in Canada (University of Alberta) and in Australia (lead from the
University of Sydney); however, these are some way from being clinical and are currently
research and development programs only. The Australian MRI-LINAC program is a $16
million project at Liverpool Hospital comprising a collaboration between the Radiation
Physics Laboratory at the University of Sydney, the Ingham Institute for Applied Medical
Research in Western Sydney and the Centre for Medical Diagnostic Technologies at the
University of Queensland. The program, led by Professor Paul Keall, is reported to be the
only one of its kind in the southern hemisphere.22 An additional study by Kishan et al (2015)
was identified examining differences between MRIdian patient plans and a LINAC-based
IGRT system in patients with soft-tissue carcinomas, however this study is as yet
unpublished and consequently unavailable.
A common group of authors collaborated on the majority of the conference papers included
in this report. It is important to note several conflicts of interest amongst these authors (see
table 1) where direct funding has been received from ViewRay Incorporated, the
manufacturer of the MRIdian system.
MRIdian ™ System for MRI-guided radiotherapy: July 2015
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Number of studies included
All evidence included for assessment in this Technology Brief has been assessed according
to the revised NHMRC levels of evidence. A document summarising these levels may be
accessed via the HealthPACT web site.
Total number of studies: 6
Total number of Level III-3 studies: 3
Total number of Level IV studies: 3
Search criteria to be used (MeSH terms)
“MRI guided radiotherapy”.
“MRI guided radiation”
“magnetic resonance imaging-guided radiation therapy”
“magnetic resonance imaging guided radiation therapy”
“magnetic resonance imaging-guided RT”
“magnetic resonance imaging guided RT”
“magnetic resonance imaging-guided radiotherapy”
“magnetic resonance imaging guided radiotherapy”
Literature Search Date
17/02/2015
References
1.
National Cancer Institute (2010). Radiation Therapy for Cancer. [Internet]. National
Cancer Institute. Available from:
http://www.cancer.gov/cancertopics/treatment/types/radiation-therapy/radiationfact-sheet [Accessed 30 March 2015].
2.
Anonymous (2014). Image-guided radiation therapy. [Internet]. American College of
Radiology and the Radiological Society of North America. Available from:
http://www.radiologyinfo.org/en/info.cfm?pg=igrt [Accessed 31 March 2015].
3.
ViewRay Inc (2012). Premarket Notification [510(k)] Summary. The ViewRay System
for Radiation Therapy. [Internet]. Food and Drug Administration. Available from:
http://www.accessdata.fda.gov/cdrh_docs/pdf11/K111862.pdf [Accessed 14 April
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