This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Gamma camera in Nuclear Medicine is used for – 
Select and explain. 
A. Organ imaging, B. Measuring the radioactivity, C. Monitoring the surface contamination, D. RIA
B: Measuring the radioactivity
Answer: B: Measuring the radioactivity 
Explanation: 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.