Abstract：Objective This paper aims to analyze the differences of setup error between CTVision and
kilo-voltage cone-beam computer tomography (CBCT) comparatively, which used to calibrate the setup
errors for nasopharyngeal carcinoma during radiotherapy. Methods A total number of 30 nasopharyngeal
carcinoma patients, who underwent intensity-modulated radiation therapy (IMRT) with immobilization
using a customized thermoplastic mask from January 2015 to August 2016, were randomly assigned
to group A and group B, 15 cases. CTVision and kilo-voltage CBCT image-guided radiotherapy were
performed in group A and group B respectively, once a week and 6 weeks each. If the setup error was
>3 mm, setup errors were corrected by adjusting the treatment couch to match the treatment isocenter.
Paired t-test was used to evaluate the differences. Results Regardless of the duration of the fractionated
radiotherapy course, the setup errors in the LR, SI and AP directions were (0.44±2.26) , (0.45±2.29)
, (-0.13±2.10) mm and (0.85±2.46), (0.50±2.64), (0.69±2.53) mm for group A and group B
respectively, without significant differences between two groups (P>0.05). The Σ and σ of group A were
0.75～0.96 mm and 0.90～1.29 mm, respectively, and the Σ and σ of group B were 0.76～1.01 mm and
1.18～1.37 mm respectively. According to the formula of ICRU 62, Stroom and Van Herk, the MPTVs
of group A were 1.32～1.51, 2.28～2.55 and 2.66～3.03 mm respectively, while 1.53～1.63, 2.45～2.85
and 2.83～3.35 mm were for group B. The MPTV in group B was slightly larger than those in group
A, but the differences were not statistically significant (P>0.05). The MPRV based on the formula of
McKenzie were 1.54～1.70 mm and 1.65～1.90 mm for group A and group B respectively. In addition, no
significant differences in setup errors were observed during the fractionated radiotherapy course (P>0.05).
Conclusion Application of CTVision and kilo-voltage CBCT can effectively correct the setup errors fornasopharyngeal carcinoma during radiotherapy. But there is no statistically significant difference
between them. In clinical applications, this paper offer best choose for different patients and different
body parts.
张全彬，彭莹莹，张书旭，
梁有腾. 应用CTVision和千伏级CBCT研究鼻咽癌放疗摆位误差的比较分析[J]. 中国医疗设备, 2017, 32(6): 74-78.
ZHANG Quan-bin,
PENG Ying-ying, ZHANG Shu-xu,
LIANG You-teng. Comparative Analysis of Application of CTVision and Kilo-Voltage CBCT
in the Nasopharyngeal Carcinoma Radiotherapy Beam Position Error. China Medical Devices, 2017, 32(6): 74-78.
