What are the differences between a traditional ct scanner and a spiral ct scanner?

Difficult to get: into the physics of it here, but a "traditional" or single slice scanner requires a separate scan for each slice. A spiral ct or multislice scanner employs a single scan with multiple detectors to acquire the entire volume of of data in the region being scanned. The patient moves through the scanner as the tube scans/rotates around the patient hence the descriptor "spiral".