Megavoltage bremsstrahlung end point voltage diagnostic

In a material, a beam of x rays is accompanied by various kinds of secondary radiation, including Compton electrons from collisions between the x rays and the material's electrons. For megavoltage bremsstrahlung in air, many of these Compton electrons are forward-directed and fast enough to be...

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Bibliographic Details
Published in:Review of scientific instruments 2009-03, Vol.80 (3), p.034301-034301-11
Main Authors: Feroli, T., Litz, M. S., Merkel, G., Smith, T., Pereira, N. R., Carroll, J. J.
Format: Article
Language:English
Subjects:
BREMSSTRAHLUNG
COMPTON EFFECT
DOSIMETRY
ELECTRIC POTENTIAL
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
LINEAR ACCELERATORS
MAGNETIC FIELDS
MAGNETS
MONTE CARLO METHOD
PARTICLE BEAMS
RADIATION DOSES
X RADIATION
X-RAY SPECTROMETERS
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Summary:In a material, a beam of x rays is accompanied by various kinds of secondary radiation, including Compton electrons from collisions between the x rays and the material's electrons. For megavoltage bremsstrahlung in air, many of these Compton electrons are forward-directed and fast enough to be deflected outside the beam's edge by a magnetic field perpendicular to the beam. At the beam's edge, the dose from the deflected Compton electrons has a pattern that depends on the radiation's end point energy. Dose patterns measured with radiochromic film on a nominally 1 and 2 MV linear accelerator agree reasonably well with the corresponding Monte Carlo computations. With further development, the dose pattern produced outside the beam by such a sweeper magnet could become a noninvasive way to monitor megavoltage bremsstrahlung, when the end point energies are difficult to determine with other methods.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.3098947