Development of a system to detect surgical materials retained in the patients under surgery

The retained materials during surgical procedures lead to serious complications forthe patients all over the world, and can even cause death. Nowadays, even thoughvarious methods and commercial products have been developed in order toprevent surgical teams from unintentionally leaving materials inside patients, asatisfactory success could not be achieved.The main aim of this thesis is to design, realize, and test a system based on radiofrequencycommunication that can detect surgical materials retained in thepatients under surgery. In this thesis, two different microprocessor controlledsystems that use commercially available receiver/transmitter modules operating at433.92 and 868 MHz radio-frequency signals were developed. The transmitters,which we referred to as tags, were placed in a chicken bought from a grocery andalso in the tanks that represented human abdomen. The tanks were filled withwater having different volumes and conductivities. The tests were performed in anenvironment similar to the operating rooms. In addition, in these tests the powerlevels obtained at the receiver with respect to the distance to the transmitter wereinvestigated. For 433.92 MHz tags, the power levels at the receiver decreased 5-10 dBm and 15-20 dBm when they were placed in the water and in the chicken,respectively, compared to the measurements taken in the open air. The resultsshowed that 433.92 MHz tags performed better than 868 MHz tags. Finally, thesetests demonstrated the proof of concept of this system in detecting surgicalmaterials retained in the patients under surgery.