Final answer:
The PCT should use the Wong-Baker Faces Scale to measure the child's pain.
Step-by-step explanation:
To measure the child's pain, the PCT should use the Wong-Baker Faces Scale. This pain scale is specifically designed for children and uses a series of cartoon faces to represent different levels of pain. The child can point to the face that best matches their level of pain, allowing the technician to assess the intensity of the pain.