[TISSUE DISSOLUTION FOR THE RETRIEVAL OF 125I SEEDS FROM STORED PROSTATE TISSUE AFTER PERMANENT SEED IMPLANT BRACHYTHERAPY: A STUDY IN PATIENTS WHO DIED WITHIN ONE YEAR AFTER TREATMENT].

(Objective) To establish a method for separating and retrieving intraprostatic radiation sources used in low-dose-rate (LDR) brachytherapy from the prostates of patients who died within one year after 125I seed implantation, we conducted dissolution experiments on autopsy-removed and preserved prostate glands using sodium hydroxide (NaOH) solution. (Subjects and methods) Two preliminary exploratory experiments were first conducted. 1) Porcine prostate and skeletal muscle tissues containing dummy 125I seed sources were lysed using NaOH solutions of three different concentrations (2.0, 4.0, and 6.0 mol/L). Source release was examined to determine the optimal NaOH concentration for prostate dissolution. 2) 125I seed sources were immersed in NaOH solution to confirm the absence of isotope leakage due to potential titanium capsule corrosion. Based on the results of these preliminary studies, dissolution experiments were then performed on two autopsy-derived prostate specimens obtained from patients who had died within one year after seed implantation, using NaOH solution. (Results) The preliminary experiments indicated that a 6.0 mol/L NaOH solution was appropriate for tissue dissolution. No 125I isotope leakage was observed after immersion of the seeds in this solution. Using 6.0 mol/L NaOH for prostate dissolution, although manual manipulation such as stirring and cutting was required, all implanted 125I seeds could be successfully separated and retrieved from the prostate tissue. (Conclusion) Using a 6.0 mol/L NaOH solution as the dissolution agent, implanted 125I seed sources were safely and effectively separated and retrieved from autopsy-derived prostate specimens obtained from patients who had died within one year following LDR brachytherapy.