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目的:通过比较鼻咽癌放射治疗的常规、整体挡铅、三维适形3种不同摆位技术方法的精度,以期找到更切合实际的摆位技术方法,提高鼻咽癌放疗的水平。方法:按照鼻咽癌三种摆位技术的操作常规,对93例鼻咽癌患者进行摆位,用医科达直线加速器的验证系统拍验证片,随机拍两张片与第一次片完全叠加,测量两片射野中心点“0”以及十字坐标线与不规则野四周4个交点A(上界)、B(后界)、C(下界)、D(前界)的绝对距离,比较3种摆位方法的精度。结果:常规组的0、A、B、C、D误差(mm)分别为2.96±1.61、3.85±1.74、3.69±2.08、2.94±1.77、2.90±1.59;整体挡铅组的0、A、B、C、D误差(mm)分别为0.71±0.80、0.50±0.63、0.83±0.77、0.69±0.93、0.93±0.86;适形组的0、A、B、C、D误差(mm)分别为0.20±0.40、0.15±0.44、0.33±0.56、0.42±0.75、0.36±0.52;三组间5个点的误差两两比较除整体挡铅组与适形组C点误差差异无显著性(t=1.89,P<0.0607)外,其他差异均有显著性(P<0.0001)。结论:三维适形和整体挡铅摆位精度和重复性明显高于常规摆位,三维适形与整体挡铅的精度虽比较接近,但适形组布野更多,射野范围更小,更能有效地保护正常组织。
OBJECTIVE: To compare the accuracy of three conventional methods of radiotherapy of NPC with three different methods of placement of lead and three-dimensional conformal in order to find a more practical method of placement and improve the radiotherapy of nasopharyngeal carcinoma. Methods: According to the routine operation of three kinds of nasopharyngeal carcinoma setup technique, 93 patients with nasopharyngeal carcinoma were placed in position. The verification system was performed with the validation system of the medical linear accelerator. The two films were randomly overlaid with the first slice , The absolute distance between the center point of two fields of field “0” and the four intersections A (upper bound), B (rear bound), C (lower bound) and D (front bound) between the cross coordinate line and the irregular quadrangle is measured and compared Accuracy of 3 kinds of setting methods. Results: The errors (mm) of 0, A, B, C and D of the conventional group were 2.96 ± 1.61,3.85 ± 1.74,3.69 ± 2.08,2.94 ± 1.77,2.90 ± 1.59 respectively; , C, D (mm) were 0.71 ± 0.80,0.50 ± 0.63,0.83 ± 0.77,0.69 ± 0.93,0.93 ± 0.86 respectively. The errors (mm) of 0, A, B, C and D in conformal group were 0.20 ± 0.40,0.15 ± 0.44,0.33 ± 0.56,0.42 ± 0.75,0.36 ± 0.52. The error of 5 points between three groups was no significant difference (P> 0.05) , P <0.0607), the other differences were significant (P <0.0001). Conclusion: The accuracy and repeatability of three-dimensional conformal and integral block lead placement are obviously higher than those of conventional placement. Although the accuracy of three-dimensional conformal and integral block lead is relatively close, the conformal group has more fields, Can effectively protect normal tissues.