The gamma camera is the device most commonly used in nuclear imaging diagnostics. It was invented in 1953 by Hal Anger and has been greatly improved ever since. The gamma camera is a device capable of detecting extremely small amount of radioactivity in the body of a subject, thus producing a two-dimensional scintigram. It consists of two basic parts, a collimator and a detector. The collimator has the ability to absorb gamma rays that are not suitable for scintigrams. The gamma rays that pass the collimator reach the detector. The detector consists of a large scintillation crystal and an array of photomultiplier tubes. The scintillation in interaction with gamma rays produces photons of visible light that are guided by optical fibers into photomultiplier tubes. Photomultiplier tubes determine the exact location of scintillation, which helps making an image, and they convert light photons into a weak electrical pulse. Electrical pulse is transmitted to the computer where the image or scintigram is created. In order to obtain a quality scintigram, we must also consider performance parameters. These are spatial resolution, sensitivity and uniformity. The spatial resolution shows the gamma camera's ability to distinguish between two objects. It is inversely proportional to the sensitivity of the gamma camera, and it is necessary to balance these scintigram parameters. Sensitivity is defined as the number of detected pulses that the detector detects for each unit of activity. Another important parameter is uniformity because various effects can make the image worse. In clinical practice, single-headed gamma cameras with a rotating stand are most commonly used because they enable tomography imaging. Two-headed cameras are also often used to allow the patient to be viewed from different angles at the same time. Each device has its own advantages and disadvantages, so does a gamma camera. The most important advantage of the gamma camera is the ability to detect pathological processes, and the biggest disadvantage is the use of ionizing rays during gamma camera examination. Radioisotopes play a major role in detecting pathological processes. The most common radioisotope in gamma camera diagnostics is technetium-99m.