心脑血管药理食管癌放疗增敏.ppt

DOSE, TIME, VOLUME AND BIOLOGICAL MODELING IN RADIOTHERAPY CLINICDi Yan, D.Sc.William Beaumont HospitalMichigan, USA Radiotherapy Modalities Fractionation Normal, hyper, hypo, and simultaneous boost Conformality CRT, IMRT, CTV-to-PTV margin, dose distribution High LET radiation 10 (g x-ray), 10 (n), 100 KeV/mm (p, a) Sensitizers or biological modifiers O2, chemo, gene drug Classic Radiobiology Framework The biological basis for fractionation total treatment time Radiosensitivity of cell survival Cell cycle kinetics (proliferation) DNA damage/repair (incomplete repair) The biological basis for conformality Dose/volume effect Molecular targeting Cell Survival During RT Cell survival fraction (log) after one and n times dose delivery Biologically Effective Dose (BED) The relationship between log cell killing and BED is always linear. Tumor Cell Proliferation During RT Tumor cell survival with consideration of tumor cell proliferation during the RT Biologically Effective Dose for Tumor with consideration of tumor cell proliferation during the RT Incomplete Repair of Normal Tissue During RT Biologically Effective Dose for a normal tissue with consideration of incomplete repair Biological Equivalence: Two dose fractionation regimens, (n1, d1) and (n2, d2) are biologically equivalent with respect to tumor control or normal tissue complication if and only if Normalized Total Dose (NTD): convert dose to NTD before applying conventional RT dose response for treatment evaluation HN: 3DCRT vs. 9 Beam IMRT (Dose-Volume Criteria) Lung: 3DCRT vs. 5 Beam IMRT Limitations of Dose-Volume-Based Treatment Planning Evaluation Dose Volume Relationship A human normal organ can be described as a structure of functional subunits (FSU) - the maximum volume that can be repopulated by one clonogenic cell nephrons in the kidney {renal tubule cells} lung {alveoli} intestine {intestinal crypts} liver {lobules} Dose Volume Relationship # cells per FSU, # of FSUs and radiosensitivity o