Final answer:
The patient has to sign an informed consent in certain situations, including when there are significant risks, for all diagnostic examinations, and if the procedure is invasive.
Step-by-step explanation:
The patient has to sign an informed consent when there are significant risks associated with the procedure or test, for all diagnostic examinations in the imaging department, and if the procedure is invasive. Therefore, the correct answer is option D: 1, 2, and 3.