1. Sudan Atomic Energy Commission, Radiation Safety Institute, P.O. Box 3001, Khartoum, Sudan
2. Physics Department, Faculty of Science, Taibah University, AL- Madina al Munawarah, Saudia Arabia
3. Nuclear Medicine Physics Unit, Kuwait Cancer Control Center, Kuwait City, Kuwait
4. Imam Mohammad Ibn Saud Islamic University (IMSIU), Deanship of Academic Research, Riyadh 11642, Saudi Arabia