DEVELOPMENT OF A RADIOPHARMACEUTICAL ACTIVITY SCHEDULE FOR TC-99M DIMERCAPTOSUCCINIC ACID IN CHILDREN BASED ON IMAGE QUALITY CRITERIA

The aim of this study was to determine an activity schedule (amount of administered activity in relation to body weight) for technetium-99m dimercaptosuccinic acid examinations in children, from information pre sent in renal scintigraphic images, Scans from 48 children (5 weeks to 14.8 years old) were graded for image quality according to the clarit y of both kidney outline and internal structure. Numerical image data (kidney and background counts, signal-to-noise ratio) were associated with these subjective gradings: to formulate three criteria, specifyin g the required values of the above-measured parameters to yield optimu m grades of image quality. When applied to derived functions, a kidney uptake of 20% was required to satisfy the criterion based on the sign al-to-noise ratio, Using this value with the other two criteria predic ts the form of the weight-dependent activity schedule as a function of imaging time. Examples of schedules for imaging times of 300 and 600 s are compared with a schedule based on surface area.