Nuclear medicine is great for viewing the roles of body organs. Medical imaging in nuclear medicine takes radioactive pharmaceuticals and studies their path of progress through patient's body. The principles of nuclear medicine are different from those of diagnostic radiology. The nuclear medicine can study the functioning of body and how it actually works. On the other hand, usage of different kinds of radiopharmaceuticals in nuclear medicine examinations can affect the dose rates. The purpose of our investigation was to estimate the effective dose from most common procedures, performed in nuclear medicine departments. We noted the injection radiation doses, which are used for diagnosis in nuclear medicine clinics. Later patient radiation doses were calculated, according to models recommended in ICRP 106.