Feature | August 28, 2013 | Raissa Rocha

New Technologies and Advances in Arc-Based Radiotherapy

This article appeared as an introduction to a Comparison Chart on Arc-based Radiotherapy in the September 2013 issue.

The variety of radiation therapy options continues to grow with the development of treatment planning software, imaging systems for guidance, linear accelerators and more. The external-beam radiation therapy (EBRT) market includes many different types of treatment, from traditional whole-body irradiation (WBI) to conformal radiation therapy (3-D CRT) and intensity-modulated radiation therapy (IMRT). Despite a major decline in 2009, the U.S. radiation therapy market is bouncing back, according to a study published in July by IMV Medical Information Division.[1] Improvements in technologies are helping to drive activity as clinics and hospitals implement advanced techniques to more accurately target and treat cancers.

Arc-Based Therapies

Arc-based radiation therapy options for physicians will vary by type of cancer and the patient’s case. Whether the cancer is prostate, head/neck, lung or breast, recent technological advances are making it easier to not only deliver higher dose to the tumor site, but to also minimize damage to healthy tissues nearby. Growing in standard use is IMRT, which delivers radiation beams from different directions around the patient as well as varies the intensity of those beams as set by the user.[2]

Further advancing external radiotherapy is the use of real-time imaging to guide delivery, to ensure beams accurately reach the tumor site during treatment. This technique is known as image-guided radiation therapy (IGRT), and offers an advantage over using previous computed tomography (CT) or magnetic resonance imaging (MRI) scans to locate glands or organs. 

While 3-D-CRT and IMRT deliver external radiation from a number of orientations set by the user prior to treatment, newer techniques offer continuous arc-based radiation around the patient to deliver even higher doses to the target while minimizing exposure to surrounding tissue. The volumetric-modulated arc therapy (VMAT) technique delivers radiation in an uninterrupted swoop around the patient, which can allow for reduced treatment times. Elekta offers VMAT in treatment systems also available with 3-D imaging technology integration to guide therapy. Similarly Varian offers the RapidArc technology to deliver continuous radiation in an arc that can be as much as 360 degrees around the patient. RapidArc can also dynamically change the intensity and shape of the radiation beams projected.

Other external techniques include proton therapy, stereotactic radiosurgery (SRS), fractionated stereotactic radiotherapy and stereotactic body radiation therapy (SBRT). Depending on where the cancer cells are in the body and the size of the target, these treatments may be used to deliver even more precise radiation dose to patients with less scatter. SRS and SBRT are growing in use for many types of cancers, such as brain and prostate, as patients seek more practical benefits for their treatment regimens, according to Cal Huntzinger, senior director of surgical sciences at Varian. “SBRT is defined as five or fewer fractions,” he said. “The big practical benefit is the reduced number of treatments. And so it’s a matter of convenience.”

Recent Advances

In the “2012/13 Radiation Therapy Market Summary Report,” IMV found that radiation oncology centers were budgeting more for new equipment purchases for 2013 than previously. However, the patient volumes reported at these centers were relatively similar over the same time period.1 The report stated that as more vendors incorporate IGRT, treatment planning and other advances into their systems, oncology centers are looking to improve their programs with these newer technologies. 

There have been several approvals of advanced technologies in external radiation therapy so far in 2013. In April Elekta received 510(k) clearance from the U.S. Food and Drug Administration (FDA) for the Versa HD, which features the Agility 160-leaf multileaf collimator (MLC) and provides high-speed beam shaping over a 40-cm by 40-cm field. It supports therapies such as SRS, SRT and VMAT. 

Treatment planning modules for proton therapy have also received approvals this year. While not yet as widely adopted as more conventional practices, proton therapy techniques are another option for treatment and can even more closely shape radiation beams to the diseased tissue.[2] Philips Healthcare’s Pinnacle3 treatment planning system for EBRT offers a module for planning proton therapy, allowing for composite proton-photon planning and automated contouring and re-planning. Users can adapt plans as necessary from photon to proton as patients undergo treatment courses. The proton module received 510(k) clearance from the FDA in August.

The release of RayStation 3.5 by RaySearch in March added tools for treatment planning of proton therapy. The Proton Beam Design module contains features such as the pencil beam dose engine and automatic generation of treat-and-protect beams. It received 510(k) clearance in May.

As the range of treatment options for external radiation therapy continues to advance technologically, look for a rise in adoption of these newest trends and advances. With increasing concerns about the amount of dose received by patients, systems that can deliver even more precise and accurate dose to the target site without damaging surrounding tissue will continue to emerge in the market. 

References

1. IMV Medical Information Division, “2012/13 Radiation Therapy Market Summary Report”

2. www.cancer.org/treatment/treatmentsandsideeffects/treatmenttypes/radiati.... Accessed Aug. 12, 2013.

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