True or False: Answer each statement with true or false and provide the cause.

Here are the answers to the questions: TRUE OR FALSE and write the cause 1. False. Nuclear medicine uses radiopharmaceuticals for both diagnosis and therapy of various medical conditions, not only for diagnosis. 2. True. This is the definition of half-life. 3. False. While radiopharmaceuticals should ideally localize predominantly in the organ of interest, some uptake in other tissues is often unavoidable. The goal is a high target-to-background ratio, not exclusive localization. 4. True. This energy range provides a good balance between tissue penetration and efficient detection by the scintillation crystal, while allowing for effective collimation. 5. True. ^99mTc decays via isomeric transition, releasing a 140 keV gamma photon, which is ideal for SPECT imaging. 6. False. Bone scans are used to diagnose a wide range of bone conditions, including fractures, infections, arthritis, and benign tumors, not only malignant cancers. 7. False. The scintillation crystal in a gamma camera is typically made of Sodium Iodide activated with Thallium (NaI(Tl)), not fluorine iodide. 8. True. PET is a quantitative imaging modality that allows for the accurate measurement of radiotracer concentration in tissues, providing functional information. 9. True. The pharmaceutical component of a radiopharmaceutical is designed to target specific biological processes or organs, effectively carrying the radioactive nuclide to the desired location. 10. False. The binding of the pharmaceutical to the radionuclide (labeling) is performed in a radiopharmacy or laboratory, not within a nuclear reactor. Reactors are used for radionuclide production. 11. False. The radioactive nuclide (e.g., ^99mTc) attached to the pharmaceutical is the source of gamma rays, not the pharmaceutical molecule itself. 12. False. Diagnostic radiopharmaceuticals are administered in trace amounts and are designed to provide diagnostic information with minimal radiation dose and no significant damage to the organ of interest. Therapeutic radiopharmaceuticals aim to damage diseased tissue, not healthy organs. 13. True. The lead collimator absorbs scattered gamma rays and only allows photons traveling perpendicular to the crystal face to pass through, thereby determining the direction of origin and improving image resolution. 14. True. PET imaging uses electronic collimation, where two annihilation photons detected in coincidence define a line of response, eliminating the need for physical lead collimators. 15. False. Renal scans are specifically designed to quantitatively assess the function of each kidney separately, providing information on individual kidney perfusion, filtration, and excretion. CHOOSE THE CORRECT ANSWER: 16. a) The half-life (T_1/2) is defined as the time required for the activity of a radioactive sample to decrease to half of its initial value. 17. b) Ideal diagnostic radionuclides emit gamma rays because they have sufficient penetrating power to exit the body and be detected by external cameras, allowing for imaging with minimal dose deposition within the patient. 18. a) Gamma rays in the range of 50-300 keV are generally considered ideal for diagnostic imaging with gamma cameras. This range allows for good tissue penetration while still enabling effective collimation and detection.