Proton Therapy Glossary L-S

  • Lawrence, Ernest O
    (1901 – 1958) was an American physicist best known for his invention, utilization, and improvement of the cyclotron, the particle accelerator that is the forerunner of the machines used in proton treatment facilities today.

  • Leksell, Lars
    (1907 – 1986), a neurosurgeon, developed the first stereotactic apparatus that was used exclusively for human neurosurgery. The Leksell Stereotactic Frame was used originally with proton therapy in the late 1950s. Later, Leksell developed the Gamma Knife, using photon beams.

  • Magnetic Resonance Imaging (MRI)
    A diagnostic imaging modality that uses a nuclear magnetic resonance technology and radio waves to produce highly detailed images of the body. Both MRI and CT scans will be used in planning proton radiation therapy.

  • Modulator Wheel
    A fan shaped spinning poly-carbide wheel with vanes of variable depth. In proton radiation therapy, the modulator wheel spreads out the thickness of the Bragg Peak. Protons passing through the thinner vanes travel farther into the body than those passing through the thicker sections. Different wheels, with different vanes, can be used to shift the peak energy (the Bragg peak) to different depths of the tumor.

  • Nozzle
    The equipment specific device through which protons are delivered to the patient. . The proton beam delivery begins in the accelerator, where an ion source generates protons; then the accelerator (synchrotron) energizes the protons to a prescribed energy and sends them to the beam transport system, which sends the beam to the treatment rooms.
    Each treatment room has a nozzle, which looks much like the nozzle of a water hose and is the final element in the beam delivery system. The nozzle not only delivers the beam to the patient, but also monitors beam uniformity, alignment, and dose delivered. The nozzle has automatic beam centering in the treatment nozzle which is key to Active Beam Scanning.
    Nozzles are sometimes referred to as “cones.” At Optivus, two types of cones have been developed. One specific to Active Beam Scanning and one is specific to Passive Beam delivery.

  • Odyssey
    The first comprehensive external beam treatment planning system that calculates for photons, protons and electrons. The featured benefits include dynamic Arc conformal shaping, virtual simulation with DCR, image fusion and a true DICOM RT compliance. Odyssey supports conformal, IMRT and Radiosurgery on the same platform with common tools.

  • Optivus Maverick™
    Thriving in a hypercompetitive marketplace is standing out in a crowd with truly distinctive ideas that drive the future of our industry. Optivus Mavericks are fearless about breaking with outdated traditions and confining standards both at work and at play. From its earliest beginnings, Optivus has always kept its eye on the "Big Picture. Putting convention and criticism aside to do meaningful work that saves and enhances lives.

  • Precision Patient Alignment System (PPAS)
    A robotic patient positioner, that delivers high patient throughput and treatment accuracy. Included in the PPAS are dual-flat panel imagers and automated registration systems. The PPAS has 10 minute treatment times and sub-millimeter precision accuracy.

  • Passive Beam
    Delivering the proton beam within one millimeter of the intended target. The passive beam scattering system allows the physician the ability to spread out the single proton beam over a target volume creating a spread-out Bragg Peak, also known as range modulation. A passive beam spreads the Bragg Peak in perhaps five-millimeter steps up to perhaps 140 millimeters, enough to cover various sized targets within the body. This system spreads out a narrow proton beam in a precise method thus creating a large field that can be used clinically.

  • Photon
    A quantum (energy packet) of electromagnetic radiation which is the elementary particle.

  • Protons
    Positively charged particles of an atom. The charge and relatively large mass (1800 times that of an electron) of protons account for the Bragg peak effect.

  • Radiation
    Energy carried by waves or a stream of particles; the sending forth of light, short radio waves, ultraviolet or x-rays or any other rays for treatment or diagnosis of cancer or for other purposes. Visible light, x-rays, and a proton beam are all examples of radiation.

  • Radiation Oncologist
    A physician who oversees the care of each cancer patient undergoing radiation treatment. They develop and prescribe each cancer patient's treatment plan and makes sure that every treatment is accurately given. They also help identify and treat any side effects of radiation therapy and work closely with other physicians of the radiation oncology team. Radiation oncologists may also use ionizing energy to treat diseases other than cancer.

  • Radiation Physicists
    Qualified medical physicists work directly with the doctor in the treatment planning and delivery. They oversee the work of the dosimetrists and help ensure that complex treatments are properly tailored for each patient. Qualified medical physicists are responsible for developing and directing quality control programs for equipment and procedures. They are responsible for making sure the equipment works properly.

  • Radiation Therapist
    A specially trained person who operates the equipment that delivers the radiation. Radiation therapist work with radiation oncologists and administer the daily radiation treatment under the doctor's prescription and supervision.

  • Radiation Therapy
    The use of high-energy penetrating rays or subatomic particles to treat disease. Types of radiation include x-rays, electrons, protons, alpha and beta particles, and gamma rays. Radioactive substances include cobalt, radium, iridium, and cesium.

  • Radiologist
    A physician specially trained to interpret diagnostic x-ray images and perform specialized x-ray procedures.

  • Radiotherapy
    Another word for radiation therapy (see above).

  • Rontgen, William Conrad
    (1845 – 1923) was a physicist at the University of Wurzburg. On November 8, 1895, he produced and detected electromagnetic radiation in a wavelength range today known as X rays or Röntgen rays, an achievement that earned him the first Nobel Prize for Physics, in 1901. He published three papers on X rays between 1895 and 1897. Today, Röntgen is considered the father of diagnostic radiology.

  • Rutherford, Ernest
    (1871 – 1937), played a major part in the great intellectual ferment of the late nineteenth and early twentieth centuries, in which discoveries in electromagnetism led to a fundamental understanding of the atom. In 1910, Rutherford's investigations into the scattering of alpha rays and the nature of the inner structure of the atom led to his concept of the atomic nucleus.

  • Simulation
    The use of special x-ray pictures to plan radiation treatment. The area to be treated is located precisely and marked for treatment.

  • Slater MD, James M
    In 1970, was recruited to develop a radiation oncology program at Loma Linda University Medical Center (LLUMC). Dr. slater graduated from Loma linda University (LLU) School of Medicine in 1963. His major field of interest prior to medicine was physics, and during his residency he became dissatisfed abut the side effects that radiation treatment often casue cancer patients. When he arrived at LLUMC to begin a radiation oncology program, he and a few colleagues began studies of heavy-charged particle radiation treatment for a hospital environment. Dr. Slater was one of the organizers of a symposium on hospital-based proton therapy systems, held at Fermilab in January 1985.

    On December 9, 2007, Loma Linda University Medical center (LLUMC), the nation's first hospital to utilize proton beam therapy for cancer, dedicated its internationally renowned proton treatment center to the founder and cancer therapy pioneer James M. Slater, M.D., FACR, vice chairman of the Department of Radiation Medicine and director of the Radiobiology Laboratories at llumc. The center was renamed the James M. Slater, M.D., Proton Treatment and Research Center on that day.

  • Synchrotron Accelerator
    Optivus' 250 MeV synchrotron accelerator is a ring of magnets through which protons circulate in near perfect vacuum. It produces the high-energy protons required for proton beam treatment. This allows for construction of large rings that can accelerate particles to much higher energies than a cyclotron which has a limited magnet size. The synchrotron provides selectable energies from 70-250 MeV, (with a 0.1 MeV resolution), as well as intensity adjustment in order to closely control the patient treatment process. The magnetic field is held constant when it reaches a value that corresponds to the prescribed beam energy. At this point, protons are slowly extracted from the ring and into the beam transport system. The synchrotron and its associated subsystems are computer controlled and monitored. The synchrotron's strengths are better suited to real world treatments. They are smaller and more reliable than cyclotron accelerators. In addition the energy of the particles can be varied as needed which is very difficult in a cyclotron. The Optivus eVe synchrotron is not only the smallest of all commercial therapeutic proton accelerators, but also the most dependable.


Proton Therapy Glossary A-K
Proton Therapy Glossary T-X