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Varian Medical Systems is an American radiation oncology treatments and software maker based in Palo Alto, California. Their medical devices include linear accelerators (LINACs) and software for treating cancer and other medical conditions with radiotherapy, radiosurgery, proton therapy, and brachytherapy. The company supplies software for ...
Varian Associates was one of the first high-tech companies in Silicon Valley.It was founded in 1948 by Russell H. and Sigurd F. Varian, William Webster Hansen, and Edward Ginzton to sell the klystron, the first vacuum tube which could amplify electromagnetic waves at microwave frequencies, and other electromagnetic equipment.
The Varians went on to found Varian Associates to commercialize the technology (for example, to make small linear accelerators to generate photons for external beam radiation therapy). Their work was preceded by the description of velocity modulation by A. Arsenjewa-Heil and Oskar Heil (wife and husband) in 1935, though the Varians were ...
As linear accelerators were developed with higher beam currents, using magnetic fields to focus proton and heavy ion beams presented difficulties for the initial stages of the accelerator. Because the magnetic force is dependent on the particle velocity, it was desirable to create a type of accelerator which could simultaneously accelerate and ...
Thus, conventional, conformal, intensity-modulated, tomographic, and stereotactic radiotherapy are all provided using specially-modified linear accelerators. Cobalt-60 beam machine from 1951 Cobalt units use radiation from cobalt-60, which emits two gamma rays at energies of 1.17 and 1.33 MeV, a dichromatic beam with an average energy of 1.25 MeV.
The Compact Linear Accelerator for Research and Applications (CLARA) is a scientific user facility at Daresbury Laboratory. It is an electron linear accelerator (linac) currently under construction in the Electron Hall. CLARA is made up of three phases; Phase 1 is operational and has achieved energies of 50 MeV with bunch charges >250 pC. Phase ...
By comparison, the charged particles produced at a site of a neutron interaction may deliver their energy at a rate of 30–80 keV/μm. The amount of energy deposited as the particles traverse a section of tissue is referred to as the linear energy transfer (LET). X-rays produce low LET radiation, and neutrons produce high LET radiation.
The main accelerator was an RF linear accelerator that accelerated electrons and positrons up to 50 GeV. At 3.2 km (2.0 mi) long, the accelerator was the longest linear accelerator in the world, and was claimed to be "the world's most straight object." [14] until 2017 when the European x-ray free electron laser opened.