"Versa HD is the culmination of many years of research, investment and collaboration," Dee Mathieson, senior vice-president, Elekta Oncology, told the assembled crowd. "It demonstrates our understanding of the underlying clinical requirements, and how we have produced new technologies to meet these ever increasing needs of our customers and their patients. Not just for today's treatments, but also for those of the future."
One of Versa HD's key selling points is its versatility. The system can deliver a wide spectrum of treatment techniques, from conventional radiotherapy through to stereotactic radiosurgery (SRS), stereotactic radiotherapy (SRT) and volumetric-modulated arc therapy (VMAT).
Versa HD is fully integrated with Agility, Elekta's 160-leaf multileaf collimator (MLC), which features 5 mm-wide leaves and delivers highly conformal beam shaping over a full 40x40 cm field-of-view. The Agility MLC also boasts the lowest radiation transmission of any commercial MLC, minimizing non-therapeutic dose.
Importantly, Agility offers a leaf speed that's more than twice that seen on other commercial systems. This ultra-fast leaf speed enables Versa HD's high-dose-rate mode, which exploits the latest advances in flattening filter free beam generation to deliver radiation doses up to three times faster than achieved by previous Elekta linacs.
Historically, MLC leaf speed was a limiting factor for delivering high dose rates. "The leaves were often incapable of moving fast enough to provide advanced modulation with the increased dose rate," explained Kevin Brown, Elekta's global vice-president, scientific research. "With Versa HD, clinicians can now take full advantage of high-dose-rate delivery, and provide highly exquisite conformance with much greater efficiency."
Brown notes that this also improves treatment times. "Over the whole range of techniques, from high dose-per-fraction through to highly complex treatments, we're seeing advancements in the treatment time, such that you'd be able to do any of these treatments in a standard treatment slot," he said. "Our research partner at Mannheim in Germany has demonstrated a 40% reduction in time for complex head-and-neck cases; and a 50% reduction in time for lung SBRT cases."
Among other features highlighted by Elekta, Versa has a 45 cm isocentre clearance that's combined with touch-activated patient protection to reduce collision risks. A 50 x 26cm cone-beam CT field-of-view enables visualization of an expanded region of interest. Versa HD is also supported by a series of anatomical packages - brain and spine; head and neck; lung; breast; and prostate - that ease treatment customization. Last but not least, the system consumes up to 30% less energy than other linacs, lowering operating costs.
Implementing SABR
The launch event continued with a presentation by Robert Timmerman, professor of radiation oncology and neurosurgery at the University of Texas Southwestern Medical Center. Timmerman described how the Versa HD could help drive the implementation of stereotactic ablative radiotherapy (SABR).
SABR is a hypofractionated treatment that comprises one to five treatments each or every other day, with the entire treatment course performed in a week or two (compared with around six weeks for conventional radiotherapy).
Timmerman cited a trial in which medically inoperable patients with early-stage lung cancer were treated using SABR. Overall survival at 36 months was nearly 60% - double that achieved historically with conventional radiotherapy. In addition, SABR may prove beneficial for treating metastatic disease. He described a clinical example in which adding SABR to drug treatment for metastatic lung cancer more than doubled the median overall survival compared to the drug alone.
"Let's get going, using equipment like this, to really try to improve cancer cure rates," Timmerman said. "Outcomes for all stages of cancer need to improve, and advanced technologies like this enable this novel and biologically different form of radiotherapy that we call SABR."
Any questions?
The launch event rounded off with a question and answer session. Responding to a question about customers, Elekta's President and CEO Tomas Puusepp noted that while the system is still pending FDA 510(k) clearance in the USA, it has received the CE mark for sale in Europe. "We have several collaborative partners, who have been part of the development process, who have signed an agreement for delivery of the Versa HD."
On the subject of how SRS will be performed on the Versa HD, Mathieson explained that various options are available, including frames, frameless operation or a bite system with thermoplastic masks. "We've discovered through the use of cone-beam CT that the image guidance accuracy on something like Versa HD is actually quite unparalleled," added Brown. "That combination of the accuracy of the imaging and the accuracy of the radiation delivery gives you a stereotactic performance without needing to use a stereotactic frame."
Looking further ahead, Brown explained that, while MLC tracking is not available commercially at present, this is an active research programme being explored by Elekta and its research partners.
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