| The linear quadratic model has been successfully used to describe the biological effects of the radiation on normal tissue and tumors. In the first part of this study a generalized extrapolated response dose equation has been developed based on the linear quadratic model to account for the variation of dose rate, incomplete repair of sublethal damage during and between fractions of irradiation. In addition this equation can deal with treatment times that are not identical for different fractions. This equation has been applied to pulsed brachytherapy treatments. The therapeutic advantage over low dose rate brachytherapy has been studied. It is seen that therapeutic advantage of greater than 1 is possible. This equation has also been used to suggest pulsing schemes that would maximize the therapeutic advantage while complying with the requirements of the Nuclear Regulatory Commission without increasing hospital personnel hours.;The second aspect studied relates to permanent implantation of the prostate. The ultrasound guided technique of implantation has improved the ease of effective radioactive source placement. Dosimetric issues that impact the outcome and thereby determine the effectiveness of the technique are actively pursued. The prostate base dose coverage; the issue of differences in prostate volume as imaged using ultrasound and CT; techniques to perform CT based post implant dosimetry; and finally various treatment strategies have been proposed, evaluated and discussed. |
