旋转摆位误差对多靶点多发性脑转移瘤患者射线剂量学参数的影响

Effect of rotational set-up error on radial dosimetric parameters in patients with multi-target multiple brain metastases

目的探讨旋转摆位误差对多靶点多发性脑转移瘤患者射线剂量学参数的影响。方法选取12例多发性脑转移瘤患者(72个靶区)CT图像,通过旋转治疗床模拟绕Z轴旋转的摆位误差(顺时针及逆时针从0度旋转至3度,步长为0.3度),比较12例患者和72个靶区旋转后和旋转前射线剂量学参数ΔD2%、ΔD98%、ΔD95%、ΔHI和ΔV100的差异。结果不同旋转摆位误差下,12例患者(72个靶区)ΔD2%比较均无统计学差异(P>0.05)。顺时针和逆时针旋转摆位误差超过0.9度时,12例患者ΔD98%、ΔD95%、ΔHI和ΔV100比较均有统计学差异(P<0.05)。72个靶区中,当顺时针旋转摆位误差超过0.3度时,ΔD98%比较有统计学差异(P<0.05);当顺时针旋转摆位误差超过0.6度时,ΔD95%、ΔHI和ΔV100比较均有统计学差异(P<0.05)。当逆时针旋转摆位误差超过0.6度时,ΔD98%、ΔD95%和ΔV100比较均有统计学差异(P<0.05);当逆时针旋转摆位误差超过0.9度时,ΔHI比较有统计学差异(P<0.05)。结论旋转摆位误差导致多靶点多发性脑转移瘤患者射线剂量学参数改变不可忽略,尤其是旋转摆位误差大于0.6度时。

Objective To explore the effect of rotational set-up error on radial dosimetric parameters in the patients with multi-target multiple brain metastases.Methods CT images of 12 patients(with 72 traget areas) with multiple brain metastases were selected, and rotational set-up error around the Z axis was simulated by rotating the treatment bed(clockwise and counterclockwise from 0 degree to 3 degrees, step length was 0.3 degrees).The differences of CT dosimetric parameters(ΔD2%,ΔD98%,ΔD95%,ΔHI and ΔV100) before and after rotation were compared among 12 patients(72 target areas).Results Under different rotational set-up errors, the ΔD2% of 12 patients(72 target areas) had no statistical differences(P>0.05).When clockwise and counterclockwise rotational set-up error was greater than 0.9 degree, the ΔD98%,ΔD95%,ΔHI and ΔV100 in 12 patients had significant differences(P<0.05).In 72 target areas, when clockwise rotational set-up error was greater than 0.3 degree, the ΔD98% had significant difference(P<0.05).And when clockwise rotational set-up error was greater than 0.6 degree, the ΔD95%,ΔHI and ΔV100 had significant differences(P<0.05).When counterclockwise rotational set-up error was greater than 0.6 degree, the ΔD98%,ΔD95% and ΔV100 had significant differences(P<0.05).And when counterclockwise rotational set-up error was greater than 0.9 degree, the ΔHI had statistical difference(P<0.05).Conclusion In the patients with multi-target multiple brain metastases, the rotational set-up error-produced changes in radial dosimetric parameters can not be negligible, especially when it is greater than 0.6 degree.