Development and testing of special device dedicated to automatic preparation of capsules for radioiodine therapy

It is a fact that production of capsules which contains high activity of ¹³¹I could be dangerous activity of professionals who work in this kind of industry. They can be exposed to high level of radiation exposure doses during manual preparation of capsules with high activities of ¹³¹I. We have developed and tested our own automatic system for this purpose. Goal of this paper is to shortly describe function and first results of testing of our system dedicated to automatic capsules filling with high activities of ¹³¹I. Our system consists of PC controlled device which is dedicated to precise dosage of ¹³¹I solution and filling of capsules with different, previously defined amounts of radioiodine activities. Whole device is located into special chamber shielded by lead bricks. Known fact that radioactive solution volume (in microliters) closely correlates with its activity (in mCi). It is basic principle of our system. First step in the whole process is precise filling of known volume of ¹³¹I solution into special syringe, using precise actuator for movement control of piston in the syringe. Next step is filling-out needed volume (i.e. activity) in the capsule by 23G needle. In order to avoid possible contamination, because of ¹³¹I is volatile, we decided to use two capsules. One smaller capsule filled with absorber is inside of one bigger capsule. Cap of bigger capsule covers small hole which remains after filling of smaller capsule. For this part of process we use special precise mechanical/electronic sub-device driven with four step-motors. Next step is measurement of ¹³¹I activity in the filled capsule using dose calibrator, and printing it value on the self-adhesive labels. Final step is transport of capsule to lead container and covering it with appropriate lead cover. Our system is controlled by PC and driven by appropriate software developed using Delphia program language. Whole process is automated, watched by two CCD cameras to establish remotely surveillance of whole process. After adjustment of all units, we have done few hundred repetitions of each step of our system we have not find any unpredictable behavior of each part of our system. Also, we found high correlation between number of steps of the piston syringe actuator and injected volume or ¹³¹I activity into capsule. Based on our preliminary testing of this system, we can conclude that system could be useful tool in production of capsules filled with high activities of radioiodine ¹³¹I. Our system enables to avoid unnecessary radiation exposure of personnel as well as to avoid errors caused by subjective or objective reasons. (author)