Study on the Application of Jaw Tracking in Intensity-modulated Radiotherapy(IMRT)for Esophageal Cancer
Objective To compare the dosimetric difference between jaw tracking(JT)and fixed jaw(FJ)techniques in static and dynamic intensity-modulated radiation therapy(IMRT)for esophageal cancer.Methods 25 esophageal cancer pa-tients were randomly selected,and the static and dynamic IMRT with JT treatment planning were created respectively,and the FJ plans were created by re-calculating with the same flounces.The dose-volume histograms and selected dosimetric indexes for the planning target volumes(PTV)and organs at risk were compared,and the 2D dose distribution of JT and FJ were also measured using portal dosimetry,and evaluated by gamma analysis.Results No significant differences between FJ and JT plans were ob-served in the PTV both on static and dynamic IMRT.However,the JT plan reduced the lung and heart dose,especially in dynamic IMRT.The average reduction for V5,V10,V20,V30,V40 and mean dose of lungs and heart on dynamic IMRT was 3.22％,1.48％,1.18％,2.12％,0.74％,1.78％,and 0.67％,0.90％,2.65％,2.23％,1.43％,1.22％,respectively.The gamma passing rates(3mm/3％,2mm/3％)is 98.19±1.17％(FJ)vs 98.56±0.64％(JT),93.33±3.45％(FJ)vs 94.30± 2.44％(JT)for static IMRT,98.36±0.84％(FJ)vs 98.62±0.71％(JT),91.77±2.83％(FJ)vs 93.31±2.35％(JT)for dynamic IMRT,respectively.Conclusion The JT technique in IMRT plans has clinical advantages and should be promoted.
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