A depth-dose measuring device using a multichannel scintillating fiber array for electron beam therapy

The development of a new depth-dose measuring device for electron beam therapy is described. The device employs plastic scintillating fiber detectors inserted in a polymethylmethacrylate (PMMA) phantom in line along an incident electron beam. Output photons from a fiber, the number of which is proportional to the absorbed dose at each depth of the phantom, were converted to an electric signal with a photodiode. Each signal from the photodiode was transmitted to a personal computer through a multichannel analog-digital converter, and was processed to draw a depth-dose curve on the computer display. A depth-dose curve could be obtained in a measuring time of 5 s for each incident electron beam with an energy range between 4 and 21 MeV. The mean electron energies estimated using the curves and the depth-scaling factor for PMMA were consistent with those obtained from conventional depth-dose measurements using an ion chamber and a water phantom. The newly developed system, being simple and not time consuming, could be used routinely for quality assurance purposes in electron beam therapy. (C) 1997 American Association of Physicists in Medicine.