Gamma camera in Nuclear Medicine is used for –: (A) Organ imaging, (B) Measuring the radioactivity, (C) Monitoring the surface contamination, (D) RIA
Answer is B. A gamma camera is a camera that records the distribution of a radioactive chemical that is taken up by a specific organ or tissue of interest. Nuclear medicine studies require the oral or intravenous introduction of very low - level radioactive chemicals (called radionuclides, radiopharmaceuticals or radiotracers) into the body. 
The radionuclides are taken up by the organs in the body and then emit faint gamma-ray signals, which are measured by a gamma camera.