"Installation begins on first MRI-linac" (medicalphysicsweb)
Autor: Tadeu Kubo | Publicado: 2014-04-14T18:29:00-03:00


source: medicalphysicsweb

Radioterapia + MRI



Installation begins on first MRI-linac

The clinical realization of MR-guided 
radiotherapy could represent the ultimate breakthrough in real-time 
image guidance – offering soft-tissue-based imaging throughout beam 
delivery. As such, researchers at the University Medical Center (UMC) Utrecht
 in the Netherlands have been working for more than a decade to overcome
 the not-insubstantial technical obstacles required to integrate an MRI 
scanner with a linear accelerator. They may finally be about to reap the
 rewards of their efforts.



Installation begins

Last Saturday, the first component of the world's first high-field 
MR-guided radiotherapy system was lowered by crane into one of UMC 
Utrecht's radiotherapy treatment rooms. While the instrument has been 
extensively tested and proven in an experimental system, this will be 
the first clinical machine to be built.





Year of progress


Already, 2014 has seen some significant developments in the field of 
MR-guided radiotherapy. Back in January, the first ever real-time 
continuous MR imaging during a patient treatment was performed using the
 ViewRay system (see First MR-guided radiation treatment).
 US medical device company ViewRay has taken an alternative approach, in
 which the linac is replaced by three gamma-emitting cobalt-60 sources 
and a weaker 0.35&nbsp;T magnet is employed. 





The Utrecht system will be the first linac-based system for 
MR-guided radiotherapy. Designed in collaboration with Elekta and 
Philips Healthcare, it comprises a 6&nbsp;MV accelerator from Elekta rotating
 on a ring gantry around a modified 1.5&nbsp;T Achieva MRI scanner from 
Philips.





According to Bas Raaymakers, associate professor in UMC Utrecht's
 radiotherapy department, the installation should take around four 
months to complete, with a working prototype ready by the summer. At 
this point, it will undergo a programme of non-clinical acceptance 
testing, including dosimetric and mechanical tests, beam alignment, 
performance evaluation of the MRI sequences and workflow definition. 





"The MRI system has been tested and the linac has been tested. 
Now the linac and the MRI will see each other for the first time in 
Utrecht, and we will see how the whole system performs," Raaymakers told
 medicalphysicsweb.





Once acceptance testing is completed, predicted to be at the end 
of this year, the researchers plan to perform a series of animal 
experiments before finally moving on to clinical testing.&nbsp;

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Collaborative approach
The development of the high-field MRI-guided linac is being led by the 
MR Linac Research Consortium, which was set up in 2012 by Elekta, 
Philips and UMC Utrecht. "Elekta is dedicated to making MR-guidance 
happen," said Jan Lagendijk, professor of radiation oncology physics at 
UMC Utrecht.




The consortium has since expanded and now also includes the 
University of Texas MD Anderson Cancer Center (Houston, TX), the 
Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital (Amsterdam,
 the Netherlands), Sunnybrook Health Sciences Centre (Toronto, ON) and 
the Froedtert &amp; Medical College of Wisconsin Cancer Center 
(Milwaukee, Wisconsin).




"Since formation of the consortium, members have been exploring 
the feasibility of high-field MR-guided radiotherapy. Installation of 
the first-generation system is truly a major step towards moving this 
technology into the clinic to benefit patients," said Raaymakers.



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