Radiopharmaceuticals are biologically active compounds that emit radiation in the form of gamma rays, positrons, or beta particles. They are used in diagnostic applications, such as nuclear medicine imaging, and therapeutic applications, such as targeting diseased cells or tissues. The Curie (Ci) unit of radioactivity is used in some contexts, while the Gray (Gy) unit is used to quantify the amount of radiation energy absorbed per kilogram of substance. Gamma rays are high-energy electromagnetic waves produced by radioactive decay and can invade our bodies and damage delicate organs. Measurement of radioactivity is essential for monitoring radiation exposure, assessing radioactive contamination, and understanding the behavior of