乳腺癌放疗中两种体位固定方式应用比较

目的:应用千伏级CBCT研究乳腺体架固定与真空垫网膜两种不同固定方式的摆位误差。 方法:选取60例乳腺癌保乳术后调强放疗患者，分为试验组和对照组。试验组采用乳腺体架固定方式，对照组采用体部固定底板+负压真空袋+热塑成型网罩体位固定方式。两组患者放疗前行CBCT扫描并在线匹配，得出左右、上下、前后方向摆位误差，对两组患者摆位误差行独立样本t检验。试验组患者每周扫描一次CBCT，连续扫描4周，对其结果行q检验，验证4次扫描的重复性。 结果:试验组患者左右、上下、前后方向的摆位误差分别为（0.27±3.61）、（0.63±4.19）、（-0.37±5.05） mm，对照组的分别为（0.64±3.25）、（-2.03±4.51）、（2.47±2.67） mm，两组在上述方向比较，t=-0.46、2.55、-2.79，P=0.650、0.014、0.007，Y轴和Z轴有统计学意义。乳腺托架患者X、Y、Z三个轴4次扫描重复性检验结果显示无统计学意义（P>0.05）。结论:在X轴方向，两种固定方式无差别，在Y轴和Z轴方向，采用乳腺体架固定方式优于采用体部固定底板+负压真空袋+热塑成型网罩体位固定方式，而且采用乳腺托架的患者重复性比较稳定。

Comparison between two different immobilization techniques in radiotherapy for breast cancer

Objective To study the set-up errors in radiotherapy with two different immobilization techniques for breast cancer via kV-cone beam computed tomography (CBCT). Methods Sixty patients with breast cancer were in cluded in this study and divided into observation group and control group. The patients in observation group were immobilized with breast bracket, while the immobilization combining immobilized carbon fiber holder, vacuum bag and thermoplastic mask was adopted in control group. CBCT scan and auto-match online were performed before the treatment to obtain the set-up errors in left-right (X), superior-inferior (Y), anterior-posterior (Z) directions, and the obtained set-up errors were analyzed with independent-samples t-test. In observation group, CBCT scan was performed once each week, last for 4 week, and SNK-q test was carried out to verify the repeatability of the 4 scans. Results The set-up errors in X, Y and Z directions were (0.27±3.61), (0.63±4.19), (-0.37±5.05) mm in observation group, and (0.64±3.25), (-2.03±4.51), (2.47±2.67) mm in control group. The t-test values in X, Y and Z directions were -0.46, 2.55 and -2.79, respectively (P=0.650, 0.014, 0.007). In observation group, no statistical significance was observed in the repeatability verification in X, Y and Z directions (P>0.05). Conclusion The two immobilization techniques doesn’t show any differences in X direction. In Y and Z directions, breast bracket is better than the immobilization technique combining carbon fiber holder, vacuum bag and thermoplastic mask in reducing the set-up errors. The reproducibility of using breast bracket for immobilization is relatively steady.