What administration method is used for Tc sulfur colloid in gastric emptying studies?

• A. Intravenous injection
• B. Subcutaneous injection
• C. Ingestion
• D. Intramuscular injection

Answer: (C)

The administration method used for Tc sulfur colloid in gastric emptying studies is ingestion. This method is specifically chosen because the study aims to evaluate how quickly the stomach empties its contents into the small intestine. By ingesting the radiopharmaceutical, it can directly interact with the gastric environment, allowing for an accurate assessment of gastric motility. The radiolabeled sulfur colloid tags the food material, enabling the imaging of the stomach and its emptying process through techniques such as scintigraphy.

Ingesting the radiopharmaceutical provides a representative evaluation of the natural digestive process, which cannot be effectively mirrored with other administration routes such as intravenous, subcutaneous, or intramuscular injections. These methods would not place the radiotracer in the gastrointestinal tract where it needs to be to assess gastric emptying, and hence they are not utilized for this particular type of study.