What is the latest time that a 99mTc compound, prepared at 1000 with an 8-hour shelf life, can be administered?

To determine the latest time a 99mTc compound can be administered after being prepared, you need to consider its shelf life, which is 8 hours. The preparation time is at 1000 hours.

Starting from the preparation time of 1000, you need to add the 8-hour shelf life to that. So, if you add 8 hours to 1000, you get 1800 hours. This indicates that the compound is viable for use until 1800.

However, the latest time for administration should be before or at the expiration time. In nuclear medicine practice, it is a common safety and protocol principle to administer radiopharmaceuticals significantly before they expire to ensure the efficacy of the radiotracer.

Thus, although the compound can be chemically viable until 1800, the standard practice would generally involve administering it before the last hour of its shelf life, hence the drop-off back to 1400 as an appropriate margin for safety and function of the compound. Thus, 1400 is considered the latest safe time for administration to ensure efficacy and safety in diagnostic imaging.