Dr. G.S. Pant joined the All India Institute of Medical Sciences (AIIMS), New Delhi, India, in the year 1971 as a Physicist in radiation oncology. In 1985, he moved to nuclear medicine, where he worked in various faculty positions before being elevated to the position of Professor (Med. Phys.) in 2003. After superannuating from AIIMS in October 2007, he worked at King Fahad Specialist Hospital (KFSH), Dammam, Kingdom of Saudi Arabia (KSA) in Medical Imaging Department as a Consultant Medical Physicist and Head of Cyclotron for a few years. Thereafter he worked as a visiting professor to AIIMS, Rishikesh, Uttarakhand in the Department of Nuclear Medicine for two years (2019-2020). He has experience of working in various disciplines of radiological sciences like radiation oncology, radiology and Nuclear Medicine. He has visited several countries as an expert in Medical Physics (Nuclear Medicine) under the aegis of the IAEA and Indian Government. He has several research publications to his credit and has edited few books. He is authoring the present book on "Introduction to the Basic Sciences in Nuclear Medicine".