University of Idaho Research Colloquium Microwave Electron Linear Accelerators for Cancer Therapy and Non-Destructive Testing: History, Application & Theory Mark Trail, Manager Microwave & Physics R&D April 10, 2008

University of Idaho Research Colloquium What is a Medical Linear Accelerator? A Medical Device designed to deliver ionizing radiation to a tumor.

University of Idaho Research Colloquium What is an Electron Linear Accelerator? Electron Gun (-25kV) A high-Q, resonantly coupled, microwave circuit that accelerators electrons to many MeV Standing Wave Microwave Circuit (3Ghz)

University of Idaho Research Colloquium  1 1895: Roentgen discovered X-rays  Shortly thereafter folks discovered that radiation kills cells It all started with Wilhelm Roentgen Definition: RADIOTHERAPY – The therapeutic application of ionizing radiation A Little History…

University of Idaho Research Colloquium More History… Russell Varian Sigurd Varian 1948:  Varian Associates Founded 1950:  Sigurd Varian prepared proposal for 10MeV Medical X-Ray Linac 1955:  Dr. Henry Kaplan builds 1 st 6MV Medical Linac 1960:  Varian Clinac-6 Treats Patients

University of Idaho Research Colloquium 1955: Dr. Henry Kaplan’s 1st 6MV Medical Linac (Stanford Medical School)  1st retinoblastoma patient. Vision intact at last check (1996) photos copyright Radiology Centennial, Inc.

University of Idaho Research Colloquium 1962: Henry Kaplan with Varian Clinac 6

University of Idaho Research Colloquium Cancer Facts… IIn the USA, LLeading Cause of Death 440% of us in this room will be diagnosed with cancer 114% of us will be treated on a Varian Linac 11.25 million new cancer cases annually  198,100 prostate  192,200 breast  169,500 lung  135,400 colorectal MMen – if you live long enough you will get prostate cancer TTreatment Options SSurgery, Chemotherapy, Radiation Therapy, or combination

University of Idaho Research Colloquium Radiation Therapy Facts…  Non-Invasive  Eradicates tumors, stops cancer cell replication or relieves pain,  Treats 50% of all cancer cases in USA  Typically, ~15min treatments, delivered 5 day/wk over 6-8 wks  Treatment is Painless - like having an X-Ray taken

University of Idaho Research Colloquium Radiation Therapy Facts… (cont)  Side effects usually temporary; Depending on treatment site, can include nausea, loss of energy & appetite.  Millions of patients have been treated  ~5000 Varian medical accelerators presently treating patients world-wide  We ship 2-3 machines a day from Palo Alto and build ~1km of accelerators/year

University of Idaho Research Colloquium Modern Medical Linacs  Generates High-Energy X-rays and/or electrons for Therapy  Rotates around the patient delivering radiation from multiple beam angles  Capable of Volumetric Cone- Beam CT Imaging  Work in special treatment rooms with 7-ft thick walls How Do They Work?

University of Idaho Research Colloquium Inside a Varian Medical Linac electron linac beam transport beam shaping

University of Idaho Research Colloquium Treatment Planning… Treatment is typically “fractionated” 20 – 30 “fractions” in 4 to 6 weeks (outpatient) Dose the tumor – spare healthy tissue & minimize exposure to critical structures. Goal Process: 1)Acquire CT and/or PET Images 2)Plan treatment 3)Irradiate from different angles 4) Vary penetration by varying beam energy 5)Shape Beam to conform to tumor

University of Idaho Research Colloquium Accelerating the electrons - the “Guide” or “Accelerator”

University of Idaho Research Colloquium Accelerator: Side-Coupled Standing-Wave Design Varian core technology! 1.5 m

University of Idaho Research Colloquium First we bake at 450C. Then pull a high-vacuum (Vacion pump) Operate at ~10 -8 torr (remove % of the air) Accelerator: Side-Coupled Standing-Wave Design

University of Idaho Research Colloquium Up to 5.5 Megawatts peak, 5 kilowatts average Fill with high power RF at 3 GHz Insert electrons Accelerator: Side-Coupled Standing-Wave Design

University of Idaho Research Colloquium

RF power input Side cavities couple rf Resonant cavities Axial electric fields electrons Accelerator: Side-Coupled Standing-Wave Design

University of Idaho Research Colloquium Beam Transport: The Bend Magnet

University of Idaho Research Colloquium Bend Magnet Directs the beam from accelerator towards patient  T T hree 90 degree bends + drift spaces  Doubly Achromatic (achromatic & non- dispersive)  One-to-one imaging, radial and transverse  Energy slits limit the energy acceptance Beam is ~ 1.5 – 2 mm diameter accelerator

University of Idaho Research Colloquium Bend Magnet Directs the beam from accelerator towards patient  Beam is directed onto a “target” to make x-rays  Or passes through for electron treatments Up to ~ 1 kw of beam

University of Idaho Research Colloquium e- Scattering Foils & X-Ray Flattening Filters Scatter e-beams and flatten X-beams to make uniform at patient

University of Idaho Research Colloquium Ion Chamber Monitor dose delivered to patient

University of Idaho Research Colloquium Collimate/Shape The Beam Limit the extent of the beam – only treat tumor

University of Idaho Research Colloquium  Tungsten blocks coarsely collimate the beam Collimator or “Jaw” System

University of Idaho Research Colloquium Fine beam collimation Because tumors don’t have corners Irregularly shaped field 120 tungsten “leaves” Multi-Leaf Collimator

University of Idaho Research Colloquium

Intensity Modulated RadioTherapy Dynamic motion of the MLC leaves while the beam is on. “Paints” irregular dose distribution  I I mproved dose distributions, better sparing of normal tissues  Treatment planning must optimize many variables  Improved efficacy of treatments  Good for the patient and… IMRT

University of Idaho Research Colloquium Very good for VAR stock price! improved dose distributions, better sparing of normal tissues treatment planning must optimize many variables information management is very important complex treatments – lots of work for the physicist IMRT Dynamic motion of the MLC leaves while the beam is on. “Paints” irregular dose distribution

University of Idaho Research Colloquium Security & Inspection Products  S S ame technology as Medical Linacs  Very different applications  Primary business is Cargo Inspection

University of Idaho Research Colloquium Mobile Cargo Inspection Systems Linatron™

University of Idaho Research Colloquium Other Security and Inspection Applications: Mega-Voltage Computed Tomography (CT) Sterilization of Medical Disposables Food Irradiation (sterilize fruit flies or kill pathogens in food) Picture of Steriliz ation Linatrons Each Accelerator Delivers: - 10 MeV electrons - 15kWavg Beam Power

University of Idaho Research Colloquium Job Opportunities at Varian:  P Presently, 30 openings in USA for all levels of engineers  Complete list available at  Please take a Varian Brochure Thanks for Your Attention

University of Idaho Research Colloquium