Quality Assurance Procedure for the Output Constancy of TomoTherapy HI-ART

  Objective  To test and assess the output constancy of TomoTherapy HI-ART.

  Methods  According to TG-148 of American Association of Physicists in Medicine (AAPM) report and by using A1SL ionization chamber, slab solid water phantom, and cheese phantom, we tested and analyzed the constancy of static output, rotational output, and energy of TomoTherapy HI-ART.

  Results  The average output variation was(-0.6±1.1)% for the static condition, and 89.1% of the collected output data were within the action level of ±2%. The average variation of rotational output was (1.0±1.1)%, and 87.1% of the collected data were within ±2%. An average energy variation was (-0.01±1.26)%, and 80% data were within ±1% and 96% data within ±2%, which showed good constancy and reproducibility.

  Conclusions  The output constancy of TomoTherapy HI-ART is less stable than conventional Linac, so it is important to test static and rotational output everyday to ensure the accuracy.