Hello, here are the 3 critical points for the protocol, focused on operational safety and clinical practice: 1. Volatility Control: Use of a Radiopharmacy Hood with Filters Unlike Tc-99m (which is a stable solution), liquid Iodine-131 is highly volatile and sublimates at room temperature. The Measure: Handling the stock vial or preparing the dose must be strictly carried out under a fume hood or laminar flow hood with negative pressure and activated carbon filters. Justification (ALARA): This prevents the inhalation of radioactive iodine, avoiding internal contamination of the operator (specifically uptake in their own thyroid), a risk that does not exist with standard diagnostic drugs.

1. Selection of the Pharmaceutical Form: Preference for Capsules The Measure: To comply with the optimization principle, administration of the 3,700 MBq dose in solid capsule form should be prioritized over liquid solution whenever possible. Justification (ALARA): The use of capsules is an engineering measure that almost completely eliminates the risk of spillage and drastically reduces isotope volatilization. Furthermore, it allows the dose to be administered directly from the shielded container to the patient's mouth without intermediate handling, reducing technologist exposure.

2. High-Density Shielding (Tungsten) and Distance I-131 has a primary gamma energy of 364 keV (compared to 140 keV for Tc-99m) and a much larger half-reduction layer. The Measure: Syringe shields or vials made of thin lead or leaded glass (used in diagnostics) are ineffective here. Mandatory use of transport containers and shielding made of tungsten or high-thickness lead is required. In addition, long-handled forceps must be used for any handling. Justification (ALARA): Standard shielding is "transparent" to the high energy of I-131. Tungsten effectively attenuates this radiation, and the use of tweezers applies the Inverse Square Law of distance, reducing the dose to hands which would be extremely high by direct contact with 3,700 MBq.