CA Health & Safety Code Section 115085

The average inspection frequency for ionizing radiation machines shall be once each year for mammography X-ray units, once every three years for high-priority sources of ionizing radiation, and once every four and one-quarter years for medium-priority sources. Sources of ionizing radiation used in dentistry shall be screened for defects by mail or other offsite methodology not less frequently than once every five years, with physical inspection of the 50 percent, determined by the department to be most in need of inspection, to average at least once every six years.