There is no particular sensor that shows the total scanned pages count but this doesn't mean that you won't be able monitor this information with PRTG. As long as the device supports a protocol that PRTG supports (SNMP for example) and as long as the device is technically able to provide this information via SNMP, there is a high chance of getting that number in PRTG.
If the device supports a protocol as SNMP review the following KB article for instructions and links to the required tool to add your MIB's SNMP Library Sensors within PRTG:. Custom Monitoring of Devices via SNMP
Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.