Final answer:
The service engineer should be notified about frequent bad streaks on the inferior slices, a consistent circle on the images, and frequent bad streaks throughout the entire image in head scans.
Step-by-step explanation:
The service engineer should be notified about frequent bad streaks on the inferior slices of head scans, a consistent circle on the images, and frequent bad streaks throughout the entire image. These issues indicate poor image quality and can be caused by factors such as release of radiation, problems with the detectors, or computer malfunctions.