CT增强扫描定位过程中不同给药途径对适形放疗体表定位标记精度的影响

The analysis of the accuracy on relocation in 3DCRT during CT scans

目的:分析经不同途径给药进行CT增强扫描定位造成的适形放疗体表定位标记的误差,探求提高适形放疗的定位精度。方法:测量CT扫描定位前后体表标记点的坐标(X轴和Z轴方向),观察平扫(A组)、经静脉直接推注(B组)和经静脉留置导管推注造影剂(C组)增强扫描各50例病人的体表标记点的误差。结果:经A组、B组、C组扫描定位后,体表标记的误差在X轴方向分别(0.18±0.6)mm、(1.54±1.93)mm、(0.18±0.6)mm,Z轴方向分别为(0.24±0.8)mm、(2.6±2.76)mm、(0.34±0.91)mm;X轴方向A组与B组,P<0.05,A组与C组,P>0.05,B组与C组,P<0.05。Z轴方向A组与B组,P<0.05,A组与C组,P>0.05;B组与C组,P<0.05。结论:三维适形放疗精确定位是精确放疗的基础,CT扫描定位过程中因静脉推注造影剂使病人的体位发生移位导致体表定位标记发生偏差,若治疗时沿用扫描前的坐标进行重复定位,必然会引起肿瘤计划靶中心与实际靶中心发生偏差,导致治疗精度的降低。通过CT定位前静脉留置,经导管给药增强扫描定位或扫描完毕后及时修正体表标记的坐标,治疗时用修正后的坐标进行重复定位,即可消除因CT增强定位导致的偏差,从而提高适形放疗的定位精度。

Objective：To analyze relocation error of CT scan by different enhance methods and how to improve accuracy of relocation in 3DCRT. Methods： By measuring body marks which were located X and Z axes, There were three group patients （ A group ： no enhance vs, B group ： enhance by vein injected vs, C group： enhance by jugular vein catheter, fifty patients in each group. All patients have marked X and Z - axes. Results： In the X axes, the error was 0. 18 ± 0.6mm in A group, 1.54 ± 1.93 mm in B group and 0.18 ± 0.6mm in C group. In the Z axes, the error was 0.24 ± 0.8mm in A group ,2.6±2.76mm in B group and 0.34 ± 0.91 mm in C group. In X axes, there was obvious difference between A and B group （ P 〈 0.05 ） ; no difference between A and C group （ P 〉 0.05 ） ; There was statistical difference between B and C group （ P 〈 0.05 ）. And in Z axes A vs. B （ P 〈 0.05 ） ; A vs. C （ P 〉 0.05 ） , B vs. C（P 〈0.05）, respectively. Conclusion： The precise relocation is the key in the 3DCRT. There was some error during CT scan. If there was error in the isocenter of tumor and planning, it make big error in the isolines on tumors. Enhanced by jugular vein catheter injecting and adjusted new site marks, these would decrease relocation error and increase accuracy in 3DCRT.