Objective To investigate the best position fixed method of lung cancer in image-guided radiotherapy (IGRT).
Methods From January 2016 to June 2017, 90 patients with lung cancer treated in our hospital were randomly selected to observe the setup errors. All patients underwent kilo-voltage cone beam CT(kvCBCT) before radiotherapy. Patients were divided into three groups: group A received negative pressure vacuum pad, group B received head and neck shoulder net cover, and group C received conjoined mesh cover. Each patient received CBCT scans five times before radiotherapy, and the images were matched with the planned CT images to measure the setup errors.
Results A total of 450 images were collected to match the translation errors of the left-right (X), head-foot (Y), and anterior-posterior (Z) directions: (3.21±2.05)mm, (2.03±1.55)mm, (3.34±2.13)mm in A group; (1.81±1.53)mm, (3.13±2.15)mm, (3.26±2.04)mm in B group; and (1.88±1.73)mm, (1.85±1.46)mm, (1.78±1.48)mm in C group, respectively. There were significant differences in A group vs. B group in X, Y directions, B group vs. C group in Y, Z directions, and A group vs. C group in X, Z directions(all P < 0.05). Rotation errors in X, Y, Z directions were(2.52±1.03) °, (4.85±1.32) °, (4.53±1.25) ° in A group, (4.54±1.12) °, (2.61±1.52) °, (4.82±1.23) ° in B group, and (2.08±1.12) °, (1.53 ±1.05) °, (1.51±1.38) °in C group, respectively. The probability of the rotation error > 3°in group C was significantly less than those in group A and B.
Conclusion The position repeatability of radiotherapy in group C with conjoined mesh cover fixed mode is good, and it is recommended that conjoined mesh cover fixed mode should be applied in the radiotherapy of lung cancer, and even chest and abdominal tumor.
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