Final answer:
The appropriate modifier for the X-ray code when a fracture of the radius is identified on one side is '-RT' for the right wrist and '-LT' for the left wrist when no fracture is found.
Step-by-step explanation:
The modifier that would be assigned to the X-ray code for the right wrist, which has a fracture of the radius at the growth plate, is likely the modifier '-RT' indicating that the service was performed on the right side of the body. For the left wrist, where no fracture was present, the '-LT' modifier would be used to specify the left side. These modifiers help ensure accurate billing and record-keeping for unilateral procedures or when a procedure is performed on one side of the body only.