Positron Emission Tomography

The aim of this study to evaluate the positron emission tomography (PET) scan technology and its role as a diagnostic tool in health care. New PET technology provide the integrated PET and CT or MRI scan have been applicated globally. In performing PET scan, a small amount of a radioactive substance (18F-FDG is widely used) is injected into a vein, and this substance is absorbed mainly by organs and tissues that use the most energy.The patients recieve internal radiation exposure from injected radiotracer and external radiation from CT component technology. PET and integrated PET seem to be used in oncology for diagnosis, tumor staging, evaluation after therapy and fnding recurrent cancer. An integrated PET/CT scan combines images from PET scan reveals any abnormal activity that might be going on tissues and organs inside the body, while a CT scan provides detailed pictures ofthere. In general, PET/CT can be considered similarly accurate to PET/MRI as whole-body staging approach. But PET/MRI will be indicated and performed superiorly to PET/CT that require high soft tissue contrast.  The average specifc activity of 18F-FDG was equal to 3.5 to 4.3 MBq/kg. In PET/CT examination,the injected18F-FDG activity was on an average 300 MBq for adult patient, and by using TOF technology the average activity decreased to 250 MBq.The average e?ective dose related to whole body PET/CT was about 14.3 mSv (8.6 mSv due to CT scan, 5.7 mSv due to PET-FDG component). Another center reported the average e?ective dose was 4.4 mSv for PET component alone and totally 13.5 mSv for PET/CT examination. A PET technology and integrated PET with CT or MRI as new machine for diagnostic imaging can be used mainly for oncologic patients. The PET/MRI technology is superior to PET/CT in detecting soft tissue contrast of organs and tissues.