What sealed source is approved for use in potable imaging devices?

Iodine-125 is the correct choice for a sealed source approved for use in potable imaging devices. It is commonly used in medical applications, particularly in brachytherapy for cancer treatment and imaging. Iodine-125 has favorable properties, such as its half-life of approximately 60 days, which allows for effective imaging while minimizing prolonged exposure to radiation.

In potable imaging devices, the materials used must be safe for use in medical settings, ensuring that they do not compromise patient safety or compliance with health regulations. Iodine-125 conforms to these safety and regulatory standards due to its established history in clinical applications and its relatively low energy emissions, which are suitable for diagnostic procedures.

While the other isotopes may have specific applications in medical imaging or therapy, they are not typically approved for direct use in potable imaging devices due to reasons such as higher levels of radioactivity, longer half-lives leading to unnecessary prolonged exposure, or regulatory restrictions. Thus, Iodine-125 remains the preferred choice in this context because of its balance between efficacy and safety.