Proton Therapy Treatment Made Possible.

In a seminal paper published in 1946, Robert R. Wilson, PhD proposed using accelerator-produced beams of protons to treat deep-seated tumors in humans. Eight years later, the first cancer patient received proton therapy treatment at the Berkley Radiation Laboratory.  Over the next four decades, proton therapy programs were launched at Harvard University (1961), the University of California, Davis (1964) and the Los Alamos National Laboratory (1974). In 1990 the first hospital-based proton therapy center opened.

Widespread adoption of proton therapy treatment has been hampered by the high cost of the technology and the massive amount of space a traditional proton therapy system commands.

Over the past two decades, proton therapy technology has become more compact and the cost of proton therapy systems has declined.

Today, more than 170,000 people worldwide have received proton therapy treatment, and the demand for treatment is unprecedented.

Proton Therapy Technology

Beam Delivery

There are three types of proton-beam delivery methods: passive scattering, uniform scanning, and pencil beam scanning. When identifying treatment options and developing treatment plans, it is important to consider the method of proton-beam delivery.

ProTom’s Radiance 330® Proton Therapy System provides pencil beam scanning. Pencil beam scanning is the most precise form of proton therapy. Using an electronically guided scanning system and magnets, pencil beam scanning delivers proton therapy treatment via a proton beam that is just millimeters wide. With pencil beam scanning, beam position and depth are able to be controlled, allowing for highly precise deposition of radiation to be delivered in all three dimensions of the tumor.

Due to the superior dose sculpting and high beam efficiencies, pencil beam scanning delivers lower doses of radiation to critical structures and healthy tissue than other proton beam delivery methods. This reduces side effects and improves long-term outcomes for patients, and improves the patient’s quality of life.^1,2

Another important consideration is that unlike other methods of beam delivery, pencil beam scanning does not require the use of patient-specific or field-specific devices (apertures, compensators) in the delivery of proton therapy treatment. This eliminates treatment delays, reduces treatment time, reduces costs, increases flexibility in treatment delivery, and reduces patient exposure to secondary radiation produced when the beam hits a device.

Types of Accelerators

For protons to reach the distal edge of a tumor, it is necessary to accelerate the proton energy. This is done with a particle accelerator. Synchrotrons and cyclotrons are the devices most commonly used to accelerate protons for use in proton therapy treatment.

Cyclotrons

Cyclotrons are composed of two D-shapes electrodes, called dees, and a large dipole magnet.  Protons are injected into the gap between the two dees. Protons are gradually accelerated by alternating the polarity supplied to the dees.  This results in the protons moving in a spiral pattern, gaining energy as they move outward.  Once the protons reach their top speed, they are directed out of the cyclotron and into the beamline by magnets. A beam degrader device is used to slow the protons to the optimal energy for treatment.

Synchrotrons

Synchrotrons are composed of a ring of small magnets. Protons are injected into the ring and begin traveling around the ring at about 10 million times per second.  A radio frequency cavity within the ring increases the energy of the protons each time they travel around the ring. By varying the magnetic and electrical fields, synchrotrons can produce protons of various energies. Once the desired energy has been achieved, the protons are directed out of the synchrotron and into the beamline. The ability to extract a variable choice of beam energy from the beamline eliminates the need for a beam degrader, thus eliminating secondary neutrons produced from beam interaction with the degrader.

Synchrotrons have low secondary neutrons and they are more energy efficient and more cost-effective than cyclotrons. Additionally, today’s synchrotrons have a small footprint. ProTom’s Radiance 330®’s compact synchrotron has the smallest footprint in the market.

Radiance 330® has been called the future of proton therapy technology. Radiance 330® delivers proton therapy treatment with the precision of pencil-beam scanning and the power of integrated imaging.

With the smallest synchrotron footprint in the market and a modular/flexible design that includes interchangeable sub-systems, Radiance 330® can be installed in purpose-built or existing facilities. Designed in close collaboration with clinical experts, it is easy to use and easy to integrate with current radiotherapy ancillary systems.

And with low capital and operating costs, Radiance 330® is affordable.

References

¹ W P Levin, H Kooy, J S Loeffler, T F DeLaney. “Proton Beam Therapy.”
Br J Cancer. 2005 Oct 17; 93(8): 849–854. Published online 2005 Sep 27. doi: 10.1038/sj.bjc.6602754

² University of Pennsylvania School of Medicine. “Studies point to clinical advantages of proton therapy: Studies demonstrated lower toxicities, positive survival outcomes for lung, pancreatic and spine cancers.” ScienceDaily. Published online 2015. Oct 19.