A simple method of obtaining off-axis half-value layers for megavoltage photon beams.
We describe a simplified technique for the acquisition of off-axis beam-quality data (i.e., half-value layers in water) for medical linear accelerators. A measurement protocol is presented in which an ordinary beam-scanning water phantom is used to accurately position an ionization chamber at appropriate measuring positions. Attenuation coefficients are calculated by performing a regression on the measured data. The technique uses the smallest fields for which lateral electron equilibrium can be established.
Barish
R J
RJ
Cancer Institute, Mary Immaculate Hospital Division, Catholic Medical Center of Brooklyn and Queens, Jamaica, New York 11432, USA.
D006801:Humans; D008433:Mathematics; D010315:Particle Accelerators; D019047:Phantoms, Imaging; D017785:Photons; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D014867:Water
D014867:Water