ThePhysicsofRadiology-chapter6-1 放射物理 英文版 教学课件.pptVIP

Radiobiology Part One Summary * * BME College Sherman Sheen(辛学刚) The Physics of Radiology four Rs the repair of sublethal damage repopulation by surviving cells in the irradiated tissues redistribution of cells throughout the division cycle reoxygenation of hypoxic cells Initial Event—The Passage of the Charged Particles EFFICIENCY of RADIATION DAMAGE TRACKS of CHARGED PARTICLES DISTRIBUTIONS IN SPACE of ENERGY RELEASES LINEAR ENERGY TRANSFER (LET) the electron tracks 0.25 keV/μm an alpha particle 250 keV/μm SPECTRUM OF LET VALUES velocity charge IMMEDIATE RADIOCHEMICAL EFFECT Production of Solvated Electrons and Radicals Dependence of Radiation Damage on LET the radiobiological equivalent (RBE) the relative efficiency of killing ASSAYS FOR PROLIFERATIVE CAPACITY —SURVIVAL CURVES COLONY ASSAY METHOD－IN VITRO IN VIVO ASSAYS spleen-colony method Limiting dilution assay In situ ASSAYS FOR PROLIFERATIVE CAPACITY —SURVIVAL CURVES COLONY ASSAY METHOD－IN VITRO IN VIVO ASSAYS spleen-colony method Limiting dilution assay In situ MATHEMATICAL ASPECTS OF SURVIVAL CURVES SINGLE HIT SURVIVAL CURVE The mean lethal dose (D0) is the dose required to reduce the population of entities from any value N to 0.37 N MULTI-TARGET SINGLE HIT SURVIVAL CURVE THERAPEUTIC RATIO where D2 is the dose that leads to serious complications in 50% of the patients D2/D1 and D1 is the dose that gives tumor control in the same % of patients. RADIOBIOLOGICAL EQUIVALENT (RBE) RBE = Dose from standard radiation to produce a given biological effect Dose from the test radiation to produce the same biological effect CELL CYCLE AND RADIOSENSITIVITY four Rs EFFICIENCY of RADIATION DAMAGE TRACKS of CHARGED PARTICLES IMMEDIATE RADIOCHEMICAL EFFECT ASSAYS FOR PROLIFERATIVE CAPACITY —SURVIVAL CURVES MATHEMATICAL ASPECTS OF SURVIVAL CURVES THERAPEUTIC RATIO RADIOBIOLOGICAL EQUIVALENT (RBE) CELL CYCLE AND RADIOSENSITIVITY