Systematic and comprehensive analysis of the doseresponsecharacteristics of a morning quality check ofa linear accelerator and an important application ofaccelerator performance prediction

Background: this paper aimed to analyze the output constancy of a medicallinear accelerator using ptw quickcheckwebline and studied the sensitivity ofthe ptw quickcheckwebline. materials and methods: the paper statisticallyanalyzed the output doses of 6 mv and 10 mv of photons and 6 mev, 9 mev,and 12 mev of electrons from a medical linear accelerator measured beforethe daily treatment to assess the output stability of a medical linearaccelerator. some modifications were introduced by artificially altering theexternal irradiation conditions, and the percent variations from baselinevalues were noted. the gantry angle was changed and some deviations wereestablished in the vertical, longitudinal and lateral directions to study thesensitivity of the ptw quickcheckwebline. the beam flatness, symmetry,radiation quality and output energy of 6 mv of photon energy werestatistically analyzed. results: among the measurements, no parametersexceeded the tolerance of ±3%. quickcheckwebline was capable of detectingthe variations in the central axis dose, flatness, symmetry and radiationquality under the testing conditions. similar to the photon energy, electronenergy measurements also confirmed that the detector was sensitive to asmall variation in output introduced by the testing conditions. an importantapplication of accelerator performance prediction in this study confirms theirreplaceable and important function of morning quality checks of a linearaccelerator. conclusions: the output dose measured before daily treatmentusing ptw quickcheckwebline to analyze the linear accelerator outputconstancy helps to decrease the system error, effectively reduces the errorsof the accelerator system, and avoids serious mistakes.