Frequency
- how often ?
- daily, weekly, monthly, annually
- after hardware or software changes (‘acceptance’)
- AAPM, IPEM
- lists not quite the same
- agreement daily (IPEM daily or weekly):
- image noise and CT number of water
- other tests:
- annually (IPEM) or semi-annually (AAPM)
- maybe more frequently to establish usual variation
- depends on importance and application