July 31, 2017 — Elekta’s magnetic resonance radiation therapy (MR/RT) system will be the subject of 21 abstracts at the 59th American Association of Physicists in Medicine (AAPM) Annual Meeting & Exhibition. The meeting is taking place July 30 - August 3 in Denver.
Elekta’s MR-linac is the only MR/RT system, according to the company, that integrates a high-field (1.5 Tesla) MR scanner with an advanced linear accelerator and intelligently-designed software. The system is expected to deliver precisely-targeted radiation doses while simultaneously capturing high-quality MR images, which will allow clinicians to visualize tumors at any time and adapt the treatment accordingly.
Elekta introduced the MR-linac technology under the name of Elekta Unity during the European Society for Radiotherapy and Oncology (ESTRO) congress in Vienna, Austria in April 2017.
Two abstracts that highlight the performance characteristics of MR-linac will be presented in a session on MR-guided radiation therapy.
- Initial Performance Tests of a High-Field MR-Linac (Abstract TU-FG-GS2-9)
This abstract reports the initial results of system level tests conducted on MR-linac by researchers at the Froedtert & Medical College of Wisconsin Clinical Cancer Center at Froedtert Hospital. The system successfully passed multiple tests assessing imaging and dosimetry performance, and the study results also demonstrate successful delivery and measurement of an intensity modulated radiation therapy (IMRT) treatment plan. The data show that the integration of a linac and a high-field MRI does not compromise the performance of either system.
- Real Time Performance of the Elekta MR-Linac Clinical Prototype (Abstract TU-FG-FS2-10)
This abstract describes results of a study undertaken to determine the ability of Elekta’s MR-linac to perform real-time motion compensation. Researchers at University Medical Center Utrecht (UMCU) conducted the study, in which experimental software was used to investigate imaging and feedback performance. Results show that the time required to reconstruct and transport image data after acquisition was 62 milliseconds, and that overall time to gate the beam was 407.6 milliseconds, including the real-time image processing of five images per second. The authors conclude that these times are promising and support real-time applications of MR-linac, such as motion compensation.
“These data underscore that Elekta’s MR-linac system meets the critical objectives of accurately delivering a radiation dose while simultaneously capturing high-quality MR images,” said Allen Li, PhD, Medical College of Wisconsin professor and chief of medical physics at Froedtert Hospital and an author on the first abstract. “The successful delivery and measurement of an IMRT treatment plan is an important milestone in the development of Elekta’s MR-linac system, which has the potential to be a revolutionary technology for cancer care.”
Additional abstracts demonstrating the potential of Elekta’s MR-linac system to improve patient care, include:
- Dosimetric Impact of MR-Linac Treatment On SBRT of Lymph Node Oligometastases Poorly Visible On CBCT (Abstract SU-H1-GePD-J(A)-4)
This abstract describes how the system improves dose volume parameters and reduces the exposure of organs at risk (OAR) compared with cone beam computed tomography (CBCT) imaging in patients with lymph node oligometastases. Researchers at UMCU conducted the research and conclude that the high-field MRI guidance that Elekta’s MR-linac provides paves the way for further dose escalation and hypofractionation.
- Fast Online Daily Replanning for Rotational Correction in Prostate Radiotherapy (Abstract SU-I-GPD-J-63)
This abstract reports that treatment replanning for prostate cancer can be done in less than two minutes with Elekta’s MR-linac and shows that daily treatment replanning led to more consistent plans and ensured target coverage enabling OAR sparing via margin reduction. The research was conducted at UMCU.
- Feasibility Study of Esophagus Adaptive Planning Using Elekta MR-Linac Beam Model (Abstract SU-I-GPD-J-101)
This abstract highlights the use of Monaco, Elekta’s treatment planning software system, in concert with its MR-linac. Results show that the presence of the 1.5T magnet did not affect the quality of the treatment plan, and that the treatment plan resulted in reduced exposure of the heart in a patient needing treatment in the esophagus. Researchers at the University of Texas MD Anderson Cancer Center conducted the research.
Geoffrey Ibbott, Ph.D., deputy division head, Department of Radiation Physics, Cancer Network Integration – Medical Physics at the University of Texas MD Anderson Cancer Center, will also give a presentation titled “MRI/Linac” in the Recent Advancement of Imaging Guidance in Clinical Trial session.
During his talk, Ibbott will discuss how a linear accelerator can be paired with a high-field 1.5 Tesla clinical magnet resonance imager to provide image-guided radiation therapy with superior soft-tissue image quality. The benefits of MR-guided radiation therapy will be addressed, and issues related to dosimetry that result from the presence of the magnetic field.
Elekta Global Vice President of Scientific Research Kevin Brown said the system is on track to submit for CE mark approval of MR-linac in the second half of 2017, followed with filing of U.S. Food and Drug Administration (FDA) 510(k) approval in 2018.
Elekta Unity is a work in progress and not available for sale or distribution.
For more information: www.elekta.com