The Future of IMRT

Clinics around the World Embrace

RapidArc Radiotherapy Technology

Since its introduction at ASTRO in 2007, Varian’s RapidArc™ radiotherapy technology has been rolling out around the world, making it possible for clinicians to deliver advanced image-guided intensity-modulated radiation therapy (IMRT) treatments in less than two minutes – two to eight times faster than could be accomplished with Varian’s technology for delivering dynamic fixed-beam IMRT.

RapidArc can deliver a complete volumetric IMRT treatment in a single rotation of the treatment machine around the patient.  RapidArc software modulates the MLV aperture shape, dose delivery rate and gantry speed throughout the rotation.  In addition to being faster to deliver, RapidArc treatments are more efficient in terms of beam output, translating to less overall “scatter” and out-of-field dose to the patient.

Besides offering meaningful clinical advantages and more convenience for the patient, the speed of RapidArc can provide a major economic benefit for clinics and patients.  Centres can treat up to 50 percent more patients per day and significantly reduce their cost per treatment, thereby making the most advanced forms of radiotherapy more accessible and affordable.

It is now no surprise to us that RapidArc has become the most successful product introduction in our company’s history.  By the end of the fiscal year, we booked more than 300 orders for this product and some 30 radiotherapy centres had completed installations and commenced treatments.  RapidArc is now being used in centres around the world to treat tumors in the prostate, head and neck, lung, brain and many other sites.  It’s already clear that RapidArc will be a major contributor in our campaign to help save the lives of more cancer patients.

RapidArc in Practice

RapidArc treatments for prostate cancer have commenced at a number of centres around the world including Premion of Brisbane, Australia; University of Alabama at Birmingham; Advanced Radiation Centres of New York; Copenhagen University Hospital (Rigshospitalet) in Denmark; Image Guided Radiation Therapy of Latham, New York; Cancer Care Associates of Fresno, California; Verity Radiation Oncology of Plano, Texas; and Decatur Memorial Hospital, Illinois.
According to Sharon McMillan, MS, DABR, medical physicist at Decatur Memorial, her comparison tests generated RapidArc treatment plans for prostate cancer that looked better than conventional IMRT plans in terms of tumor coverage.  Randi Aaronson, PhD, medical physicist at Verity, has produced RapidArc plans for prostate cancer that provided IMRT-like PTV coverage and normal-tissue sparing, while reducing the monitor units delivered during treatment by 30 percent and the treatment time by 70 percent.

At the Centre for Radiation Therapy of Beverly Hills, Henry Yampolsky, MD, has now used RapidArc radiotherapy to treat glioblastoma multiforme, head and neck cancer and metastatic bone lesions.  In one case, Yampolsky treated a 76 year old man with a lesion in the L-2 vertebral body of the spine and another in the iliac bone.  “We decided to use RapidArc to deliver a three-fraction stereotactic treatment for each lesion, one right after the other,” Yampolsky says.

“Both lesions had been treated previously.  We got very good plans with RapidArc, and without it, each lesion would have required 20 to 30 minutes to treat.  We couldn’t see any reason to subject the patient to an hour long treatment each day when, with RapidArc, we could get him in and out in less than 15 minutes.”

On the other side of the United States, in Melbourne, Florida, Todd Scarbrough, MD, of the MIMA Cancer Centre, is also making use of RapidArc for a diverse set of indications.  Recently, Scarbrough used it to deliver stereotactic body radiotherapy (SBRT) in the treatment of soft tissue carcinoma.  RapidArc was used for another patient with a small right parietal brain metastasis from lung cancer as part of a frameless fractionated stereotactic radiosurgery treatment.  “We compared the RapidArc plan with a 14-beam noncoplanar IMRT plan,” says Scarbrough.  “The RapidArc plan was essentially equal to the 14-beam plan, but with a tighter 50 percent isovolume (which means the low dose spillover region was smaller).  But the RapidArc treatment was deliverable in three minutes.  The other treatment would have taken forty.”
“RapidArc technology is the future of IMRT”, says Ben Slotman, MD, chair of the Vrije Universiteit Medical Centre in Amsterdam, the Netherlands, where clinicians have now used RapidArc in the treatment of multiple brain metastases.  Their protocol calls for whole brain radiation, followed by stereotactic booster doses targeted at the metastases.  “With RapidArc, we can deliver the whole brain and boost doses targeted at the metastases.  “With RapidArc, we can deliver the whole brain and boost doses simultaneously, which is not possible with standard IMRT techniques,” says Slotman.  “Treatment planning and delivery are also both much quicker with RapidArc,” he adds, pointing out that his treatment team can develop detailed RapidArc plans in roughly half the time it takes to develop a standard IMRT plan.

RapidArc’s single-arc IMRT has already been very well received by the oncology community.  Still, Varian continues to improve and innovate in the area of arc IMRT.  In keeping with the company’s long standing tradition of developing versatile and uncompromising solutions, new functionality has been added to Varian’s RapidArc radiotherapy technology.  RapidArc technology now enables noncoplanar as well as multiple arc IMRT treatments that enable geometric avoidance of some organs at risk while increasing uniformity of tumor dose.

“Using noncoplanar fields makes it possible for clinicians to create plans that avoid certain parts of the anatomy in ways that wouldn’t be possible when treating with just one arc, in just one plan,” explains Corey Zankowski, senior director for oncology product management at Varian.  “For example, this approach can be useful for treating brain tumors located in the same plan as the eyes.  By rotating the couch during treatment to deliver multiple noncoplanar arcs, clinicians can often avoid the eyes to a large extent and achieve a better dose distribution to the tumor.”

In addition to supporting multiple and noncoplanar arcs, the latest version of RapidArc further supports stereotactic applications by increasing the number of monitor units that can be delivered per beam (or per gantry rotation).

“We are delighted with the tremendous interest in RapidArc, which promises to be a formidable weapon in the battle against cancer,” says Tim Guertin, Varian Medical Systems president and CEO.  “We’re seeing the strongest demand we’ve seen for a new product, reflecting the need for faster, more user-friendly systems that enable clinics to offer patients greater access to high-quality, image-guided IMRT treatments.”