Nuclear medical imaging is considered one of the most important modern technologies in the diagnosis and treatment of cancer patients. It relies on the use of radioactive substances known as radioisotopes to visualize biological functions داخل the body with high precision. Unlike conventional imaging methods that mainly show anatomical structures, nuclear imaging highlights cellular activity, making it an effective tool for early tumor detection and for determining the extent of cancer spread. One of the most prominent nuclear imaging techniques used in oncology is Positron Emission Tomography (PET), which is often combined with Computed Tomography (CT) in what is known as PET/CT technology. This technique involves injecting the patient with a radioactive tracer such as Fluorodeoxyglucose (FDG), a substance that is absorbed more by cancer cells due to their high metabolic activity. This allows precise identification of tumor locations, even at early stages. Another technique is Single Photon Emission Computed Tomography (SPECT), which works in a similar way but differs in the type of radiation used and the detection method. This imaging modality helps evaluate the functions of various organs, such as the heart and bones, and assists in detecting cancer metastasis to these organs. The role of nuclear medical imaging is not limited to diagnosis; it also extends to treatment through what is known as targeted radionuclide therapy, or “theranostics.” In this approach, the same radioactive substances are used to destroy cancer cells. For example, radioactive iodine (I-131) is used in the treatment of thyroid cancer, where it is selectively absorbed by cancerous cells and destroys them with minimal damage to healthy tissues. Among the key advantages of nuclear medical imaging are its high accuracy in locating tumors, its ability to assist physicians in selecting appropriate treatment plans, and its usefulness in monitoring patient response to therapy. It also reduces the need for exploratory surgical procedures. However, the use of radioactive materials requires strict safety precautions to ensure the protection of both patients and healthcare professionals. Al-Mustaqbal University: Ranked First Among Iraqi Private Universities