Researchers aim to improve flash therapy for X-ray and proton delivery

December 13, 2018
by Thomas Dworetzky, Contributing Reporter
Dramatic cuts to cancer treatment times – and making treatment technology more compact – got a boost from new funding for two accelerator-based projects; one using X-rays, the other using protons, now in the works by the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University.

The PHASER X-ray project uses “rapidly scanned beams from many directions through electromagnetic steering with no mechanical moving parts, and is referred to as pluridirectional high-energy agile scanning electron radiotherapy,” according to a Stanford report on the work. It is designed to create a flash delivery system able to slash radiation times to under a second from minutes, as well as devising compact technology that can make advanced radiation therapy available more widely.

The new funding includes a $1.7 million grant from the DOE Office of Science Accelerator Stewardship program to develop the technology over the next three years. In addition, the Stanford Department of Radiation Oncology is putting in approximately $1 million over the next year to support the work. Along with the School of Medicine, it has also set up the Radiation Science Center, of which the PHASER project is a division.

“Delivering the radiation dose of an entire therapy session with a single flash lasting less than a second would be the ultimate way of managing the constant motion of organs and tissues, and a major advance compared with methods we’re using today,” said Billy Loo, an associate professor of radiation oncology at the Stanford School of Medicine.

To deliver such high-intensity radiation this efficiently, noted chief scientist for the RF Accelerator Research Division in SLAC’s Technology Innovation Directorate, Sami Tantawi, “we need accelerator structures that are hundreds of times more powerful than today’s technology.”

The just-received funding will let researchers build such structures, said Tantawi, a professor of particle physics and astrophysics.

Over the last few years, PHASER has developed and tested prototype accelerators with novel shapes. The new designs are already working as predicted in simulations – setting the stage for designs that are more powerful and compact.

That division, co-led by Loo and Tantawi, hopes to turn that concept into a working device.

“Next, we’ll build the accelerator structure and test the risks of the technology, which, in three to five years, could lead to a first actual device that can eventually be used in clinical trials,” Tantawi said.

Another goal of the researchers is to devise innovative ways to manipulate proton beams that will make future devices simpler, more compact and much faster, according to SLAC staff scientist Emilio Nanni, who leads the project with Tantawi and Loo, adding that thanks to the DOE grant, “we can now move forward with designing, fabricating and testing an accelerator structure, similar to the one in the PHASER project, that will be capable of steering the proton beam, tuning its energy and delivering high radiation doses practically instantaneously.”

The hope is that the PHASER work could then lead to proton devices able to fit into a standard shipping container – allowing the approach to be used more widely around the globe.

“The first broadly-used medical linear accelerator design was invented and built at Stanford in the years leading up to the building of SLAC. The next generation could be a real game changer – in medicine and in other areas, such as accelerators for X-ray lasers, particle colliders and national security,” noted Tantawi.

Peter Maxim (now at Indiana University) co-invented PHASER at Stanford. Others involved in the proton therapy effort include Reinhard Schulte at Loma Linda University and Matthew Murphy of Varian Medical Systems.

In October, Varian’s new single-room proton therapy system was unveiled at the ASTRO Annual Meeting in San Antonio, along with the company’s research initiative involving flash therapy.

The ProBeam 360° cuts irradiation time of the ProBeam platform by 75 percent and offers a 30 percent smaller footprint than its predecessor, reducing vault construction costs by approximately 25 percent. Use of the system is expected to open access to potential next-generation treatments such as flash therapy, the focus of Varian’s new research group, the FlashForward Consortium.

“The average irradiation on a current ProBeam System is 45 seconds to 60 seconds. In your overall day, that’s not a huge chunk. But we’re able to reduce it by 75 percent, bringing a lot of the moving tumor irradiations to under five seconds,” Jan Timmer, U.S. director of PT marketing at Varian, told HCB News at the time. “For lung patients, you can do irradiation in one breath-hold. We think that will increase the use of protons in lungs and lung SBRT.”