OBJECTIVETo evaluate the clinical feasibility of daily quality assurance for linac radiation field by analyzing the trend of the daily testing data about parameter of radiation field.

METHODSTwo-dimensional ion chamber array Daily QA3 was used to measure the difference between the practical value and the standard value of the parameter about radiation field before commencing daily treatment. Farmer type ionization chambers from IBA Co. with DOSE1 dosimeter was used for the absolute dosimetry of photon and electron beams. Light/radiation field coincidence was checked by using films every month. The daily testing data (from 11/28/2009 to 4/8/2011) were reviewed and analyzed.

RESULTSX-ray and electron output was increasing steadily; light/radiation field coincidence, beam flatness constancy and symmetry of X- ray and electron was keeping stable.

CONCLUSIONThe procedures for daily quality assurance of linac radiation field, which will provide reference for long term linac calibration, are feasible in our experience.