RESUMO
Plastic scintillating detectors (PSDs) have found numerous dosimetric applications in radiotherapy due to their approximate water equivalence at high energies and their small physical size. At low photon energies, however, the ratio of mass attenuation coefficients (PSD : water) deviates from unity, which potentially limits their utility in this range. In this work, measurements of orthovoltage cutout factors were made with PSDs and and ion chamber. Results were compared to Monte Carlo simulations of the same geometry. Results indicated that the PSDs performed better than the IC in almost all field sizes. Further work is required to more thoroughly characterize the Monte Carlo model of the x-ray unit and to investigate any discrepancies that might have resulted from slight differences in the effective point of measurement of the two detector systems.
