According to the NRC, a written directive is required for the administration of which radiopharmaceutical?

In the context of nuclear medicine and regulatory requirements, a written directive is necessary for the administration of specific radiopharmaceuticals as outlined by the Nuclear Regulatory Commission (NRC). This is particularly true when it comes to therapeutic doses of radiopharmaceuticals, which typically have significant safety and therapeutic implications for patients.

In this scenario, F-18 FDG (fluorodeoxyglucose) is primarily utilized in PET imaging and doesn't usually require a written directive because it is not administered in amounts that exceed the specific threshold defined by the NRC.

On the other hand, Strontium-89 (Sr-89) chloride is used for therapeutic purposes, specifically for palliative treatment of bone pain associated with bone metastases. The administration of Sr-89 in the therapeutic range necessitates a written directive as it falls under the guidelines for the administration of therapeutic radiopharmaceuticals, which requires physician oversight and validation of administration.

While I-131 and P-32 would typically require a written directive due to their physically therapeutic nature and potential risks at certain dosages, the question seeks to distinguish among these options based on their NRC classifications. In the case provided, while the answer given is noted as D (20 mCi F-18 FDG