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 numb er 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 thro ugh 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 measureme nts using an ion chamber and a water phantom. The newly developed syst em, being simple and not time consuming, could be used routinely for q uality assurance purposes in electron beam therapy. (C) 1997 American Association of Physicists in Medicine.