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Title:: Correlation between TQA data trends and output of helical tomotherapy

Author(s):: CHEN Jihong; ZHANG Xiuchun; BAI Penggang; LU Jun; CHEN Wenjuan; CHEN Kaiqiang; LI Qixin; HU Cairong; LIN Jinyong; Department of Radiation Oncology, Fujian Cancer Hospital/Fujian Medical University Cancer Hospital, Fuzhou 350014, China

Keywords:: helical tomotherapy tomotherapy quality assurance static output beam quality

Abstract:: Objective To discuss the relationship between tomotherapy quality assurance (TQA) data trends and output of helical tomotherapy (HT). Methods The correlations between static output and output energy variation (D20/D10) were determined based on the retrospective analysis on the parameters and data trends of each module of TQA of HT in recent 3 years. Results The offset parameter of z axis in step-wedge static module had the best correlation with the static output of HT (r=0.883, P<0.01). The exit detector flatness in basic dosimetry module was the most sensitive to energy changes (r=0.902), followed by energy differences in step-wedge static module (r=0.897) and energy differences in step-wedge helical module (r =0.852), and their sensitivities were 2.3×10-4, 3.1×10-4 and 5.7×10-4, respectively. Conclusion TQA can help user to monitor the changes in the output and energy of HT, thereby carrying out necessary maintenance and dosimetric validation earlier.