21 - Proton Beam Therapy

21 - Proton Beam Therapy - Physics and Clinical...

Info iconThis preview shows pages 1–15. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Physics and Clinical Applications of Proton Therapy Lecture #21 Tarun K. Podder Brody School of Medicine at ECU April 05, 2011 Outline Proton Beam Production and Transport Proton Beam Delivery Techniques Clinical Applications of Proton Therapy Dosimetry, QA PROTON Proton consists of 2 up quarks (+2/3 e), 1 down quark (-1/3 e) Quarks are elementary particles spin: Fermions u, d, c, s, t, b Leptons: electrons, neutrinos As charged particle, proton traverses a circular path in magnetic field Proton Interactions Interacts with atomic electrons and nuclei Coulomb force Inelastic collision with atomic electrons in which protons lose part of their KE to produce ionization and excitation of atom and thereby resulting in absorbed dose; negligible amount of bremsstrahlung interactions Elastic collision without loss of energy Mass stopping power for proton is greater in low-atomic- number (Z) materials than in high-Z materials High-Z materials: more scattering, less loss of energy As the particle velocity approaches zero near the end of its range, the rate of energy loss become maximum Bragg Peak PROTON ACCELRATOR Cyclotron Single dipole magnet Cyclotron frequency: charged particle orbits at a constant period Depends on mass, charge, B field See http://www.vk2zay.net/calculators/cyclotron.php Protons are injected in the center of the magnet, and spiral outwards to larger radius Acceleration occurs when crossing the D electrodes Continuous beam, high flux As velocity approaches c, relativistic mass gain makes cyclotron frequency out of sync with constant accelerating RF field PROTON ACCELRATOR Synchrocyclotron Constant B field Particle beam bunched Low average flux Frequency of RF accelerating field changed to match relativistic mass gain PROTON ACCELRATOR Synchrotron Constant curvature of accelerating orbit Changing B field strength to match particle momentum Must accelerate a single bunch to max energy, then go on to next bunch Series of bend magnets Quadrupole focusing Proton Beam Production and Transport - Cyclotron Cyclotron Beamline Nozzle Degrader Energy Selection System (ESS) Tuning Cyclotron (spiral path) Constant magnetic field Variable Radius Continuous Beam Fixed beam energy Requires Energy Selection Slit Proton Accelerators Energy Degrader and Selection magnetic field Energy selection slits Energy Degrader Range in patient: 24 g/cm 2 cyclo range: 33 g/cm 2 range = 24.1 g/cm 2 range = 24.0 g/cm 2 range = 23.9 g/cm 2 Illustration by R. Slopsema Energy Degrader and Selection Photos from Y. Yongen Proton Beam Production and Transport - Synchrotron Illustration by G. Coutrakon Proton Beam Line Beam bending: Dipole magnets Beam focusing: Quadrupole magnets Beam steering: Steering coils Proton Beam Line Beam position monitoring: Beam Profile Monitors (BPM) OK BPM Reading Outline...
View Full Document

Page1 / 70

21 - Proton Beam Therapy - Physics and Clinical...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online