Daily CLINAC QA results with arccheck in elekta synergy

Abstract

Introduction ArcCheck (Sun Nuclear, FL) is a 4D detector phantom designed to check helical treatments in radiotherapy. The phantom software and detectors data accessibility makes possible to use this phantom in LINAC QA (lineal accelerator quality assurance). Purpose Develop a daily LINAC QA program using ArcCheck phantom that checks dosimetry parameters and evaluate the results after 5 months. Materials and methods The LINAC is an Elekta Synergy. The QA steps are: •Full arc warning up beam (FAW). Warms up the ionization chamber placed inside the phantom with a beam that covers the whole phantom (20 cm inplane, 2.5 cm crossplane). Make a gamma analysis with 20% threshold comparing the measured with the reference state. •Static beam. Irradiate a 10 × 10 cm static field and import the detectors dose from an Excel Workbook that evaluates beam shape, beam quality factor, dose output and diodes signal degradation. •Irradiate a VMAT treatment. Make a gamma analysis comparing the measured with the reference data in order to check monitor unit system, gantry speed and MLC reproducibility Results •FAW: The result in SNC patient must be a uniform dose distribution in the detector matrix. It has detected misalignments in sagittal laser direction as low as 0.3°. •Static beam: All measured parameters are in tolerance. •VMAT treatment: The gamma analysis has a coincidence of more than 95% every day. These results are in agreement with other QA test. All QA take less than 8 min. Conclusion The daily QA developed is fast, complete and effective. Disclosure None. ArcCheck (Sun Nuclear, FL) is a 4D detector phantom designed to check helical treatments in radiotherapy. The phantom software and detectors data accessibility makes possible to use this phantom in LINAC QA (lineal accelerator quality assurance). Develop a daily LINAC QA program using ArcCheck phantom that checks dosimetry parameters and evaluate the results after 5 months. The LINAC is an Elekta Synergy. The QA steps are: •Full arc warning up beam (FAW). Warms up the ionization chamber placed inside the phantom with a beam that covers the whole phantom (20 cm inplane, 2.5 cm crossplane). Make a gamma analysis with 20% threshold comparing the measured with the reference state. •Static beam. Irradiate a 10 × 10 cm static field and import the detectors dose from an Excel Workbook that evaluates beam shape, beam quality factor, dose output and diodes signal degradation. •Irradiate a VMAT treatment. Make a gamma analysis comparing the measured with the reference data in order to check monitor unit system, gantry speed and MLC reproducibility •FAW: The result in SNC patient must be a uniform dose distribution in the detector matrix. It has detected misalignments in sagittal laser direction as low as 0.3°. •Static beam: All measured parameters are in tolerance. •VMAT treatment: The gamma analysis has a coincidence of more than 95% every day. These results are in agreement with other QA test. All QA take less than 8 min. The daily QA developed is fast, complete and effective.