呼吸幅度对旋转容积调强剂量分布的影响研究  

Effect of respiratory amplitude on the dose distribution of volumetric modulated arc therapy

作　　者：刘苓苓[1] 费振乐[2] 李兵兵[1] 夏莉[1] 张利伟[1] 王宏志[1] 

机构地区：[1]中国科学院合肥物质科学研究院肿瘤医院,合肥230031 [2]解放军第一○五医院肿瘤诊疗中心,合肥230031

出　　处：《中华放射医学与防护杂志》2016年第3期220-224,共5页Chinese Journal of Radiological Medicine and Protection

基　　金：本研究成果由中国科学院合肥物质科学研究院院长基金(YZJJ201325)资助,没有可能影响研究结果的财务关系

摘　　要：目的研究呼吸幅度对旋转容积调强放疗（VMAT）剂量分布的影响。方法采用呼吸运动模拟模体（QUASAR）模拟人体头脚方向的一维呼吸运动，二维电离室矩阵采集不同呼吸幅度等中心层面的剂量分布。通过Verisoft软件及绝对剂量分析，分析采集数据与计划数据比较的剂量分布、等中心绝对剂量百分误差和射野通过率。结果呼吸运动对靶区等中心点剂量影响小于剂量允许误差5％（t=-22．614～-10．756，P〈0．05），使靶区边缘剂量偏高、靶区内热点少、冷点多，且随着呼吸幅度的增大，对靶区整体剂量分布影响越大。6、8、10mm整个射野γ通过率与静态相比差异有统计学意义（t=3．095、8．685、14．096，P〈0．05）。8、10mm靶区内射野通过率与静态相比差异有统计学意义（t=6．081、9．841，P〈0．05）。结论呼吸运动可导致VMAT剂量传输误差，且误差随靶区运动幅度的增加而升高，且呼吸运动方向靶区边缘的正常组织实际治疗受照剂量高于计划评价。Objective To study the effect of the respiratory amplitude on the dose distribution of volumetric modulated arc therapy （VMAT）. Methods Respiratory motion simulation phantom （QUASAR） was used to simulate the respiratory movement from head to toe, and a two-dimensional ionization chamber matrix was used to collect the dose distribution in isocenter with different respiratory amplitude, Verisoft software and absolute dose analysis were used to analyze dose distribution, percentage errors of absolute dose in isocenter, passing rates of radiation field for the data collected, and results were compared to planned dosage. Results The effect on isocenter target dose of respiratory motion was below dose tolerance 5% （t = -22.614 - -10.756, P〈0.05）. The respiratory movement made the dose on the edge of the target area higher, with fewer hot spots and more cold spots in the target area. As the respiratory amplitude increased, the effect of respiratory movement on the overall dose distribution in the target area was greater. The difference of the whole beam γ passing rate between 6, 8, 10 mm and stationary state was significant （ t = 3. 095, 8. 685, 14. 096, P 〈 0.05 ）. The difference of targetγpassing rate between 8, 10 mm and stationary state was significant （t =6. 081,9. 841, P 〈0.05）. Conclusions The respiratory movement could cause the dose transmission errors of VMAT, the error increased with increased range of motion. The actual radiation dose for normal tissues along the direction of respiratory movement on the target edge was higher than what was planned.

关 键 词：呼吸运动幅度 旋转容积调强放疗(VMAT) 剂量分布 呼吸运动模拟模体 

分 类 号：R730.55[医药卫生—肿瘤]