摘要
目的探讨热塑头颈肩膜的收缩对头颈部肿瘤放疗患者靶区精度及剂量的影响。方法将规格为50 cm×33 cm的热塑头颈肩膜,放入65℃～70℃的热水中,待其变软和完全透明后取出,用毛巾吸干膜上的热水,用手背试膜的温度合适后,将网膜覆在头颈部仿真模体,模拟患者从制作头颈肩膜到放疗的整个过程,测量在治疗的过程中由于头颈肩膜收缩引起的靶区中心位置的偏移及对靶区剂量的影响。结果热塑头颈肩膜的收缩程度在前15 min内最大,纵轴方向约6 mm,在20 min后至5周时间内的一个疗程中由于头颈肩膜收缩引起的中心点的移动度在左右（X方向）、头脚（Y方向）和升降（Z方向）方向分别为（-0.15±0.41）mm、（0.55±0.48）mm和（-0.31±0.27）mm。模拟中心点的移动得出原发肿瘤及重要危机器官剂量变化范围：原发肿瘤大体肿瘤体积（GTV）剂量变化为-0.03%～0.06%,左侧转移淋巴结GTV剂量变化为-0.14%～0.58%,右侧转移淋巴结GTV剂量变化为-0.18%～0.43%,左侧晶体剂量变化为-2.97%～1.77%,右侧晶体剂量变化为-2.04%～3.18%,脊髓剂量变化为-2.26%～3.55%,脑干剂量变化为-3.44%～3.75%。结论为患者制作头颈肩膜时,冷却时间应不小于20 min。在此前提下,头颈肩膜收缩引起的靶区中心位置的偏移及对靶区剂量和危机器官的影响才能在可接受的范围内。
Objective To explore the effect of the shrinkage of thermoplastic mask on the dose of radiotherapy target. Methods Get some thermoplastic mask with the size of 50 cm × 33 cm,put them into 65 to 70 degree hot water,take out the soften and completely transparent mask,dry with a towel,test the temperature of mask,then put it on the head and neck phantom,simulate the procedure that from making mask for patients to radiation therapy. The effect of isocenter accuracy and the target dose which caused by the shrinkage of thermoplastic mask were measured. Results In the first 15 min,the thermoplastic mask had largest shrinkage,the longitudinal axis of approximately 6 mm. From 20 min to 5 wk,the movement of target positioning caused by the shrinkage of thermoplastic mask were left-right（ LR） direction（-0. 15 ±0. 41） mm,superior-inferior（ SI） direction（ 0. 55 ± 0. 48） mm,anterior-posterior（ AP） direction（-0. 31 ±0. 27） mm. Simulate mobile the isocenter,then calculate change of the target dose and crisis organ dose：primary tumor gross tumor volume（ GTV） was-0. 03% ～ 0. 06%,metastatic lymph nodes on the left GTV was-0. 14% ～ 0. 58%,metastatic lymph nodes on the right GTV was-0. 18% ～ 0. 43%,left lens was-2. 97% ～ 1. 77%,right lens was-2. 04% ～ 3. 18%,spinal cord was 2. 26% ～ 3. 55%,brain stem was-3. 44% ～ 3. 75%. Conclusions The cooling time should be more than 20 min,when making a mask for the patient. In this context,the effect of the shrinkage of thermoplastic mask on target positioning accuracy and the target dose is acceptable.
出处
《中国肿瘤临床与康复》
2015年第12期1430-1432,共3页
Chinese Journal of Clinical Oncology and Rehabilitation
关键词
热塑膜
收缩
靶区精度
靶区剂量
Thermoplastic mask
Shrinkage
Positioning accuracy
Target dose
