Erfan Bayat - B.Sc. Student, Amirkabir University of Technology/Mechanical dept., Tehran;
Ali Azimi - Assistant Professor, Amirkabir University of Technology/Mechanical dept., Tehran;
Hamid Naderan Tahan - Assistant Professor, Amirkabir University of Technology/Mechanical dept., Tehran;
Seyyed Mohammad Mortazavi - B.Sc. Student, Amirkabir University of Technology/Mechanical dept., Tehran;
Parisa Azimi - Assistant Professor of Neurosurgery, Neuroscience Research Center, Shahid Beheshti University of Medical Sciences,Tehran;

Defects in the focal point of a phased array of transducers have always been a desperate problem in many cases, like drug delivery or tumor eradication. They reduce the precision in targeting the infected cells and tumors, which could end to irreparable harm or, in some cases, demise due to excessive heat in tissues and their neighboring organs during the surgery. In this regard, two different methods for tumor cell eradication by ultrasound non-invasive surgery are reviewed, and the problems which are caused due to the above- mentioned defects are discussed. Manufacturing defects in transducers and their directivity may cause defects in the focal point of an array of transducers. As this may result in a failure during non-invasive ultrasound surgery, we have made a device with the capability of determining the directivity of transducers with reasonable precision. Next, we checked the directivity of a hundred transducers against their catalog. Consequently, by conducting the experiment, directivity problems were deemed to be an intrinsic, widespread problem in the transducers that have been tested. Therefore, due to the directivity problems, they cannot focus exactly on the desired point, and this may cause problems while focusing them on a point.

Directivity, High Intensity Focused Ultrasound, Ultrasound Transducer, Directivity Detector.