而自旋两圈才和原来一样的粒子.ppt

Proton Radiotherapy LET RBE 低LET射线，RBE值低(≤1.0)，高LET射线，RBE值高(≥2.0)。高LET射线的RBE，在达20keV/μm以上时，随LET升高而迅速上升，同时OER下降，但当超过160keV/μm时，RBE值反又减小，而OER下降到1。高LET射线的RBE大，在细胞存活曲线上体现D0值(平均致死量)低，且其RBE值随分割照射时的分次剂量大小而改变，即每次剂量越小，RBE值越大。 The PDD comparisons of varies rays Electron beam 电子线用于浅表组织的治疗 How to treat moving target? Movement and deformation RPM — Real-time Position Management Respiration synchronised imaging and treatment The Real-time Position Management? (RPM) system is a non-invasive, video based system that allows for clean imaging and treatment of lung, breast, and upper abdominal sites. The RPM system is accurate, easy to use and fast. It is comfortable for the patient and accommodates both breath hold and free breathing protocols. The problem of RPM 4D real time tracing system 四维实时跟踪放疗 4D Tx delivery “Visualization”: Internal magnetic marker displacement (Calypso) Calypso system: response Next step after RPM Thank you for your kind attention ! 1. Liner Energy Transfer. （线性能量传输） LET for short LET = △E △X KeV/μｍ 2. Ionization induced Direct and Indirect effects 电离对靶分子的间接作用与直接作用 Direct ： Directly act on target molecules ( Break DNA double strands ) 直接作用: 直接引起DNA双链断裂 Indirect：Affect target molecules via ionized excitated water molecules H2O 间接作用：通过水分子电离、激发 再作 用到靶分子 3. Oxygen Enhancement Ratio . OER （氧增强比） OER = D0 (dose for killing hypoxic cells乏氧细胞) D0 (dose for killing aerobic cells有氧细胞) 4. Relative Biological Effect . RBE （相对生物效应） RBE = Doses which create a certain bio-effect by one standard ray 产生一定生物效应标准射线剂量 Doses which create the same bio-effect by another ray 产生同样生物效应另一种射线剂量 5. The characteristic of high LET rays 高LET射线的特点 a. There is a Bragg Peak b. RBE 大，OER 小 c. Direct effects is major 直接作用为主，致死性损伤 Cell phase independent 细胞时相差异小 (Only for hig