Exposure rates in high-level-control fluoroscopy for image enhancement.

High-level fluoroscopic boost options that exceed conventional exposure limits are available as a means of reducing quantum mottle during angiography. Federal law does not specify exposure limits for such high-level controls but requires specific means of activation to safeguard against inadvertent use. The American Association of Physicists in Medicine recently recommended that high-level exposure rates not exceed 2.58 mC/kg/min (10R/min). At six institution surveyed, maximum exposure rates ranged from 5.42 to 24 mC/kg/min (21-93 R/min). Activation of high-level capability varied from a simple foot switch to a keyed interlock requiring a second operator to engage. There appears to be no industry coherence in high-level control exposure limits as yet, although the Center for Devices and Radiological Health recently initiated an investigatory program.