个体化乳腺癌放射治疗体位固定技术改进方法研究

目的探索个体化乳腺癌放疗体位固定技术的改进方法。方法乳腺癌患者40例,A组(20例)采用乳腺托架固定,B组(20例)采用真空袋、直肠癌体架和热塑体膜联合固定法固定。利用EPID拍摄患者治疗前位置验证片,比较两组摆位误差。结果 B组摆位误差明显优于A组,患者左右(X)、上下(Y)、前后(Z)方向和旋转(R)误差分别为,A组:X(2.90±1.77)mm、Y(3.85±1.98)mm、Z(3.25±1.94)mm,R(1.67±1.27)°;B组:X(1.80±0.70)mm、Y(2.30±1.17)mm、Z(1.75±1.02)mm,R(0.55±0.42)°。两组各项指标差异均有统计学意义(P<0.05)。X、Y、Z三方向摆位误差>5 mm的比例分别为A组15.0%、35%、25%,B组为0、5%、0。B组PTV外放边界由A组的7.04 mm、9.09 mm、7.86 mm缩小至4.09 mm、5.42 mm和4.21 mm。结论新方法整体摆位准确性明显提高,特别是摆位误差≥5 mm的发生率显著下降,PTV的外放边界进一步缩小,减少肺和心脏等正常组织照射体积。

An improved method of individualized breast cancer radiotherapy immobilization technology

Objective To explore an improved method of individualized breast cancer radiotherapy immobilization technology. Methods 40 breast cancer patients for this study were divided into Group A and B. Each group contained 20 patients. The patients of group A were immobilized with mammary gland bracket, and the patients of group B were combined fixed with vacuum bag, colorectal cancer shelf and thermoplastic mask. The electronic portal imaging device（EPID） was used to screen imaging in pre-treatment, compared the setup errors of Group A and B. Results The setup errors in group B was significantly better than group A. The mean setup deviations in the left-right（X）, up-down（Y）, anterior-posterior（Z） and rotational（R） direction were X（2.90±1.77）mm, Y（3.85±1.98）mm, Z（3.25±1.94）mm, R（1.67±1.27）° respectively in Group A, and X（1.80±0.70）mm, Y（2.30±1.17）mm, Z（1.75±1.02）mm, R（0.55±0.42）° respectively in Group B. The P value of each assessment indicators is less than〈0.05 with a significant difference. The percentages of the setup errors over 5mm in X, Y, Z directions were 15.0%, 35%, 25% respectively in Group A and 0%, 5%, 0% respectively in Group B. The margin for PTV were reduced from 7.04 mm, 9.09 mm, 7.86 mm respectively in Group A to 4.09 mm, 5.42 mm, 4.21 mm in Group B respectively. Conclusions The overall positioning accuracy of the new method has been significantly improved, especially the incidence of ≥5 mm of setup errors decreased significantly. It can further reduce the margin of PTV and reduce irradiated volume of lung and heart.