Is there a way to check dopamine levels in the brain? would a pet scan be of any benefit?

PET scan: Pet scans in hospitals use glucose metabolism to measure body function. The majority of pet scans are done to look for cancer growth and recurrence there are markers for Dopamine but these are still largely in preclinical or experimental design stages. Besides, parkinson's disease, work is underway to enable pet scans to diagnose alzheimer's disease as well. Excellent question.