头部热塑膜固定于乳腺托架联合标记线提高乳腺癌调强放疗摆位的准确性

Use head thermoplastic mask and breast bracket with body markers for breast cancer patient improves setup accuracy of intensity-modulated radiotherapy

目的:探讨乳腺/胸壁和锁骨上、下区一体化调强放疗时,采用头部热塑膜固定于乳腺托架,配合标记线对减少摆位误差的作用。方法:研究对象为行调强放射的10例乳腺癌术后病人。每例病人在乳腺托架固定下,分别放置3个摆位:无头部热塑膜固定和核对颈胸部标记线(A组)、核对颈胸部标记线(B组)、头部热塑膜固定与核对颈胸部标记线(C组)。每例病人每周1次,共5周,在X线模拟机下复核,得到和比较3个模式下照射野中心、锁骨区棘突和锁骨测量点的摆位误差值。所有病人的治疗采用C组摆位。结果:每组得到47组数据,3组摆位共141组数据。比较3组照射野中心的左右、头足和前后方向摆位,C组摆位误差显著小于A、B组(P<0.05)。锁骨区棘突的左右位移,距离锁骨头下缘越往上,摆位误差越大。A、B、C组在棘突锁骨头上6 cm处,左右位移>5 mm的病人分别占12.8%、6.4%和2.1%。除了棘突锁骨头上缘和其上方1、2 cm处外,C组其他不同测量点处的摆位误差均小于A、B组(P<0.05)。在锁骨头内缘外侧7 cm处,C组锁骨测量点的头足摆位误差也小于A、B组(P<0.001)。结论:在乳腺托架联合头部热塑膜和标记线固定下,照射野中心点、锁骨区棘突和锁骨摆位误差较小,能满足乳腺癌调强放疗摆位准确性的要求。

Objective To study the effect of using head thermoplastic mask and breast bracket combined with body marker to decrease setup errors in intensity-modulated radiotherapy(IMRT) of chest wall and clavicular region. Methods Ten breast cancer patients receiving IMRT on chest wall and sup/infraclavicular regional lymph nodes after breast surgery were enrolled. Each patient with breast bracket was immobilized into 3 positions: using breast bracket only(group A),using body marker with breast bracket(group B) and using body marker and head thermoplastic mask with breast bracket(group C). Setup errors of irradiation field center, spinous process of clavicular region and clavicle were examined using X-ray simulator once a week for 5 week with each position and compared. All ten patients were treated IMRT with position in group C. Results A total of 141 set of data in all 3 groups(47 set of data each group) were gotten. The setup errors of irradiation field center in 3 directions of left-right, superior-inferior and anterior-posterior in group C were significantly less than those in group A and B(P<0.05). Setup errors of spinous process of clavicular region in left-right direction increased with the distance from inferior margin to above of clavicular head. There were 12.8%, 6.4% and 2.1% of setup errors more than 5 mm in left-right direction at 6 cm above clavicular head in group A, B and C, respectively. Setup errors of patients in group C were significantly less than those in group A and B(P<0.05) except for those of superior margin of clavicular head and 1 cm, 2 cm above clavicular head. Setup errors of clavicle in superior-inferior direction in group C were significantly less than those in group A and B(P <0.001). Conclusions Head thermoplastic mask and breast bracket combined with body markers could reduce setup errors of irradiation field center, spinous process of clavicular region and clavicle, which improved setup accuracy of IMRT for breast cancer patients.