Effect Of ～(125)Ⅰ Seed Interstitial Implant On Tumor Inhibition And Development Of A Treatment Planning System For Tumor Therapy

Part I: Distribution of dose rate on cultured cell plane exposed to 125I seed irradiation invitro.Objective: To study the distribution of dose rate on cultured cell plane delivered by 125I seedplanar irradiation, and to establish a reference table on dose rate of 125 I seed planar irradiator forcell lines in vitro.Methods: A 1mm3 high sensitive cubic TLD was used to measure the irradiation dose rate of asingle 6711 model 125I seed with apparent activity of 10.323MBq in water at point P (point P is 1cm away from the center of the seed, the connection line between point P and the center of theseed is perpendicular to the long axis of the seed). Meanwhile, the theoretical value of theirradiation dose rate at point P was calculated with a formula provided by literature. The differencebetween the calculated and experimental values was set within the range of 10% as standard toanalyze accuracy of the measurement. Then, the irradiation dose rate of a single 6711 model 125Iseed was measured in 1mm-thick polystyrene + water medium at point P. The value was applied todifferential or non-differential proof along with the value from water medium to study the effect of1mm thick polystyrene on distribution of irradiation dose produced by a single 125I seed in water.Furthermore, nine 125I seeds were arranged in a planar circle, and the irradiation dose at a pointoutside the plane was measured. And the calculated irradiation dose of 9 seeds was derived from aformula calculating the irradiation dose rate of a single-seed in water. The feasibility of applyingthe single seed formula to calculate irradiation dose rate of multiple seeds was studied bycomparing the experimental and calculated values. Finally, by simulating the 125I seed planarirradiator with nine 125I seeds, the distribution of irradiation dose rate on the plane of cultured cellswas calculated with the single seed formula so as to select the best way of irradiation.Results: The experimental value (n= 10) of irradiation dose rate with one 125I seed in water atpoint P was(0.3589±0.0229)cGy/h, the calculated value was 0.3472 cGy/h, the difference ofwhich was within the range of 10%. The experimental value (n= 10) of irradiation dose of one 125Iseed in 1mm-thick polystyrene + water medium at point P was (0.3502±0.0273)cGy/h, whichmade no statistical difference from the experimental value in water under differential andnon-differential proof. The experimental value (n=10) of irradiation dose of nine 125I seeds at a - 5 -复旦大学博士学位论文 英文摘要point outside the seed plane was (8.1734±0.4189)cGy/h and the calculated value with thesingle-seed formula was 8.89 cGy/h. The reference table on the distribution of dose rate for cellsexposed to 125I seed irradiation in vitro was developed and an optimal irradiating strategy forfuture work was determined.Conclusions: The experimental methods of the study were accurate and feasible. 1mm-thickpolystyrene had no significant effect on the distribution of irradiation dose rate from 125I seeds inwater. The single seed formula was applicable for calculating that of multiple seeds. A referencetable on the distribution of dose rate for cells exposed to 125I seed irradiation in vitro wasdeveloped. The ideal irradiating strategy placing the cell dishes 5mm above the 125I seed irradiatorfor the next part of the study was set up on the base of 9 125I seeds with apparent activity of27.75MBq per seed.Part II: 125I seeds irradiation induced apoptosis of human breast cancer cells in vitroObjective: To study the effect of low dose rate and continuous irradiation with 125I seeds ininducing apoptosi...