Which of the following instruments should be used to determine whether all removable contamination has been eliminated?

The well counter is specifically designed to measure radioactivity in small samples and is highly sensitive to detection of low levels of contamination. This makes it an effective tool for assessing whether all removable radioactive contamination has been eliminated from a surface or an object. When using a well counter for this purpose, the item in question can be placed in the well, and the instrument will provide a precise measurement of any remaining radioactive material. This is particularly crucial in nuclear medicine environments, where even minimal contamination can pose safety risks.

In contrast, the Geiger Mueller counter, while useful for detecting and measuring radiation in the environment, is less sensitive to low levels of contamination compared to the well counter. A dose calibrator is specialized for measuring the activity of radiopharmaceuticals prior to administration, making it unsuitable for assessing removable contamination. The uptake probe is used primarily for measuring the uptake of radiopharmaceuticals by the body and is not designed for contamination detection or monitoring on surfaces. Thus, the well counter is the most appropriate instrument for this specific task.