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Proton Therapy - Frequently Asked Questions
For Clinicians
Background on Proton Therapy
What is proton therapy?Proton therapy is a major technological advance in cancer care. It uses protons, accelerated to about two-thirds the speed of light, or more than 100,000 miles per second, to destroy cancer cells. Yet it minimizes exposure to nearby healthy tissues. Like traditional radiation, proton therapy may be used in conjunction with other therapies such as surgery or chemotherapy.
How does proton therapy functionally target tumors?
Proton therapy differs from traditional radiation therapy in the way the energy is delivered to the patient. Protons deliver most of their energy at a prescribed, programmable distance inside the body, known in physics as the Bragg Peak. As a result, very little dose is delivered along the path prior to the target.
Clinicians are therefore able to:
Treat tumors surrounded by critical organs while sparing healthy tissues Frequently use high levels of radiation to effectively target cancer cells Reduce side effects common in traditional radiation therapy
Types of Cancers Treated
For which types of cancers is proton therapy typically used?
Proton therapy can be used to treat any tumor for which radiation is indicated, and it is most often used for tumors that are close to critical structures such as:
Brain Bone & Soft Tissue
Breast – particularly left breast since the tumor may by near the heart
Gastrointestinal Lung
Head and neck Ocular
Liver Prostate
Proton therapy is particularly effective for localized, non-metastasized tumors. It can also be used to treat recurrent tumors in patients who have received prior radiation treatment.
Is proton therapy used only with adults?
Proton therapy is also effective for pediatric patients because it is precisely targeted to deliver dose only to the tumor. Such precision in therapy can spare nearby organs that are still growing and developing, which may prevent future side effects. This factor has added importance because pediatric patients have so many years of post-treatment years ahead of them. Therefore, proton therapy may offer benefits for certain childhood cancers. 3
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To what extent is the demand for radiation therapy likely to grow?Although proton therapy was first proposed to treat cancer by Dr. Robert R. Wilson4 just after World War II, and patients have been treated with proton therapy for over two decades, pencil beam scanning has been used commercially since 2009.
It's estimated that new cancer cases will grow to over 20 million by 20305, 6 and, if future treatment patterns parallel today's, 60-75% of patients will undergo radiation therapy.7 Many proton centers are in the planning or construction phases, since proton therapy is increasingly an option in cancer care.
Is proton therapy typically reimbursed in the United States?
Proton therapy is indicated "for precision radiotherapy of lesions, tumors, and conditions anywhere in the body where radiation treatment is indicated," and nearly all U.S.
insurance providers provide reimbursement for proton therapy, as do Medicaid and Medicare. However, specific coverage guidelines can vary among commercial insurers. Proton center staff may need to work with private insurers to facilitate authorization for reimbursement, or to address patient-specific questions. For example staff may need to provide an insurer with a letter of medical necessity, or evidence verifying that proton therapy is appropriate in specific cases
Proton Therapy Delivery via Scanning—a Major Advance in
Radiation Oncology
Pencil Beam Scanning vs Passive Scattering
The two types of proton delivery systems are pencil beam scanning and passive scattering. Pencil beam scanning employs 3D images to determine the tumor's exact location and contours, allowing therapy delivery to that precise shape, size, and depth. Scanning, as the most precise form of proton therapy available, offers several benefits over passive scattering:
Can deliver high therapeutic doses
Provides a highly conformal dose to the tumor
Sculpts doses to the complex shapes of individual tumors—and therefore can be applied to tumors near critical structures
Spares more healthy tissues adjacent to the targeted tumors
Produces fewer neutrons than passive scattering, and thereby delivers a lower radiation dose to healthy tissue
Penetrates in a more precisely targeted manner than passive scattering, which aids in treating deep-seated and/or complex tumors
In the vast majority of cases, requires no beam-modifying devices, physical compensator, or apertures—and thus does not involve post-therapy storage of these radioactive devices
Allows for rapid, flexible re-planning without the need to fabricate, and manually insert, such devices
Is the only technology to deliver intensity-modulated proton therapy (IMPT), which is both more sophisticated and more precise than other forms of proton therapy
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As Zhang et al. pointed out, "IMPT has shown great advantages over PSPT [passive scatter proton therapy] in reducing dose to normal tissues. . . More importantly, IMPT allowed radiation dose escalation." In many instances higher doses confer greater therapeutic efficacy.1Similarly, Frank et al. noted that IMPT "has the ability to spare surrounding healthy tissue from damage and help preserve quality of life."2
Are all pencil beam scanning systems alike?
No, the functionality varies. Here are some of the ways that the Varian ProBeam® system stands apart from other proton systems with PBS:
It offers fast layer switching, an average of less than 1 second per layer switch. Proton therapy is delivered at 2G/L/min, with a small spot size across the full energy
range.
It offers streamlined workflow: its one integrated user console, which features a single screen with full functionality, does not require operator intervention (e.g., no need to request the beam, wait for an operator to release it, and access multiple screens), and treatment is typically completed with the push of a single button. Remote operation allows the user to treat multiple fields without entering the
treatment room between consecutive fields, which minimizes manual actions. Remote functions controlling the gantry, table motion, and patient positioning can be
operated from inside the treatment room but more often are accessed from the external control room.
The average treatment time for centers using the ProBeam system is approaching treatment times similar to linac (photon) centers.
How does Varian stand out as an industry leader?
As the world's leading manufacturer of medical devices and software used to treat cancer and other conditions with radiation, Varian has been pioneering advances in radiation technology for over 65 years. It is the only radiation oncology company to offer the full suite of oncology treatment solutions, including proton therapy.
Leadership in Pencil Beam Scanning for Proton Therapy
It created the world’s first commercially available proton system to deliver pencil beam scanning (PBS).
It is the first company to invest in and to exclusively use PBS.
Its PBS technology has been used to treat thousands of patients since 2009. It continually advances intensity-modulated proton therapy (IMPT) technology
through ongoing investment and research.
It is helping to set the standard for proton technology. Leadership in Radiation Oncology
It has more than 65 years of providing scientific innovations that save lives. It is the world's leading manufacturer of medical devices and software used to
treat cancer and other conditions with radiation.
It specializes in products for radiotherapy, proton therapy, radiosurgery, and brachytherapy.
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Leadership in the Corporate Environment It is working to offer emerging countries the quality of care that can be found in developed countries.
It continues in the tradition of Varian’s founders, who set out to create a company that found ways of using focused energy to solve human problems. Corporate decisions are based on the idea of “doing well” while “doing the right thing.” Leadership for the Environment
It is rated among the greenest companies in the U.S. by the influential Newsweek Green Rankings.
It is the highest ranking medical device company in the 2015 Corporate Knights Global 100, which ranks the Global 100 of Most Sustainable Companies. It is aggressively working towards marked reductions in carbon footprint,
greenhouse gases, energy use, water consumption, and solid waste disposal. Varian as a Pioneer in Its Early Years
Varian Medical Systems’ mission is to focus energy on saving lives—and it has been doing so since the Varian brothers began channeling their creative ideas into new products in the 1930s.
Brothers Russell and Sigurd Varian developed the first klystron—allowing creation of a new type of microwave radar system that was light enough to be used in aircraft. This radar is credited in part with helping the Allies win World War II. (A klystron is a linear beam vacuum tube.)
The Varian brothers founded one of the first high-tech companies in the Silicon Valley of California.
The company that they formed in 1948—initially with just six employees—went on to make linear accelerators for photon radiation therapy.
Ion pumps and other Varian technology played a key role in helping astronauts land on the moon in 1969.
Varian is an industry leader, with a singular focus on helping to save lives.
How the ProBeam System Stands Apart
How is the ProBeam system differentiated from other proton systems? Some of the features of the ProBeam® system include:
Dynamic Peak™ Scanning, which delivers high-speed intensity-modulated proton therapy (IMPT)—the most precise form of proton therapy available. The proton beam is "painted" on the tumor in tiny segments—sometimes thousands of spots—from multiple angles. For each spot, the beam intensity modulates according to the treatment plan. Other features of Dynamic Peak Scanning include:
Pencil beam scanning (PBS) so that the proton beam conforms to the size, contour, and depth of the targeted tumor
Improved dose conformity and dose control No need for beam-modifying devices Rapid treatment
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Fully rotating gantry, of 190° in either direction, allowing imaging and treatment at any angle while minimizing the need to reposition the patient—enabling faster, more efficient treatment times.An isochronous superconducting cyclotron, which offers these features: Operates with no warm-up phase
Delivers a stable and continuous beam, at a sufficient and scalable beam intensity to treat tumors at depths of 4-30 cm without range shifters
A beam transport system, designed specifically for (not adapted to) PBS, which focuses and shapes the small beam size necessarily for IMPT—allowing clinicians to target very small spots across the full energy range
Dynamic Peak™ Workflow, which offers efficient transition from prep to patient set-up to treatment, includes:
Intuitive interface, and a single console integrating imaging, planning, treatment delivery, and oncology information
Automatic sequencing of fields with remote motion and imaging control Automatic sequencing of beam requests
Dynamic Peak™ Imaging, with an onboard kV system, allowing a choice of dual X-rays and 3D cone beam computed tomography (CBCT) for accurate patient positioning. A sophisticated patient positioning system, which has these characteristics: The robotic treatment table moves into position automatically and can be operated
from inside the treatment room, or remotely from the control room—eliminating the need to enter the room to make table adjustments.
It incorporates all six degrees of freedom of movement. Its hand pendants are designed for single-handed functionality.
Use of the ProBeam system will be immediately intuitive to anyone familiar with the Varian TrueBeam™ photon delivery system, and all Varian equipment is integrated with use of Eclipse™ planning system and ARIA® information management system. This
makes training staff faster and easier if they are already used to the Varian interfaces.
Multi-Room vs Single-Room Choices
The ProBeam® system is available in multi-room and single-room options. Its multi-room systems can be designed for a cancer center's specific needs, offering up to six
treatment rooms to handle higher volumes of patients. The single-room ProBeam Compact's small footprint is the size of three linac vaults or 20 parking spaces, allowing many established photon centers to add proton to their treatment offerings. It's important to note that the ProBeam Compact is the only single-room system that offers all the options noted here. [LINK to earlier Q: "How is the ProBeam system differentiated from other proton systems"]—in other words, full functionality without compromise.
Both the multi- and single-room systems deliver the workflow functionality many are accustomed to when using Varian linacs (photon systems), such as more flexible imaging and larger treatment area per angle treated. These full-function features make treatment more efficient—and can help shorten treatment times.
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Varian Support
How can Varian support a facility's adoption of the ProBeam system?
Varian offers full support to facilities wanting to add proton therapy to their practice: Configuration: Varian works with customers to determine clinical needs and
business requirements (e.g., capacity based on expected need, revenues, expenses, return on investment, required timeline, and other integral factors), so the customer can select the optimal system
Design and finance: customers receive support identifying architectural design and possible financial partners
Building design: Varian offers the option to work with proven proton therapy architects and general contractors, or with vendors of your choice
Construction and installation: a Varian project manager works with the general contractor and with engineers to coordinate the arrival, assembly, and installation of all components
Training: customers are fully prepared for their roles with demonstrations, hands-on experience, courses, and other tools designed for the needs of diverse clinical staff On-site support: to ensure that each ProBeam® system is functioning optimally,
customer service is always available to answer any questions and troubleshoot any situation
A partner with each proton center, Varian shares clinicians' goal of treating more patients with the highest quality therapy to achieve excellent clinical outcomes.
Proton Therapy Availability and Insurance Coverage
Where is Varian’s proton therapy currently available?As of 2015, Varian ProBeam® systems are treating patients at the following: Rinecker Proton Therapy Center, Munich, Germany
Scripps Proton Therapy Center, San Diego, USA Paul Scherrer Institute, Switzerland
Additional centers under development include:
Saudi Particle Therapy Centre, Riyadh, Saudi Arabia Proton Therapy Center, St. Petersburg, Russia Georgia Proton Therapy Center, Atlanta, USA Maryland Proton Treatment Center, Baltimore, USA Dallas Proton Treatment Center, Dallas, USA
Cincinnati Children's Hospital Medical Center, Cincinnati, USA
University College London Hospitals NHS Foundation Trust, London, UK The Christie NHS Foundation Trust, Manchester, UK
The New York Proton Center, a consortium including Memorial Sloan Kettering Cancer Center, Mount Sinai Health System, Montefiore Health System, and ProHEALTH, Medical Management, LLC, NYC, USA
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1 Zhang X, Li Y, Pan X, et al. Intensity-modulated proton therapy reduces normal tissue
doses compared with intensity-modulated radiation therapy or passive scattering proton therapy and enables individualized radical radiotherapy for extensive stage IIIB non-small cell lung cancer: a virtual clinical study. Int J Radiat Oncol Biol Phys. 2010;77(2): 357–366. doi: 10.1016/j.ijrobp.2009.04.028
2 Frank SJ, Cox JD, Gillin M, et al. Multifield optimization intensity modulated proton
therapy for head and neck tumors: a translation to practice. Int J Radiat Oncol Biol Phys. 2014;89(4)846–853.
3 Chang AL, Yock TI, Mahajan A, et al. Pediatric proton therapy: patterns of care across
the United States. Int J Particle Ther. 2014;1(2):357-367.
4 Wilson RR. Radiological use of fast protons. Radiology. 1946:47:487-491. doi: http://dx.doi.org/10.1148/47.5.487
5 International Agency for Research on Cancer (IARC).
http://www.iarc.fr/en/publications/pdfs-online/wcr/2008/wcr_2008.pdf
6 American Cancer Society. Global Cancer Facts & Figures 3rd Edition. Atlanta:
American Cancer Society; 2015.
7 National Cancer Institute. http://www.cancer.gov/cancertopics/research/proton-therapy
