Patient skin dose in cardiac interventional procedures: conventional fluoroscopy versus pulsed fluoroscopy

To investigate whether pulsed fluoroscopy reduces a patient's exposure compared with the exposure owing to conventional (continuous) fluoroscopy, we simulated the skin radiation doses of patients at cardiac catheterization facilities with various X-ray systems used in fluoroscopically guided intervention procedures.

Although many reports have noted that "pulsed fluoroscopy" provides important further reductions in radiation exposure, it has been determined that when comparing dose rates between different vendor systems, "pulsed fluoroscopy" does not reduce patients' exposure as compared with "conventional fluoroscopy".

We examined 13 X-ray systems; 10 used pulsed fluoroscopy and three used conventional fluoroscopy. The entrance surface doses with fluoroscopy were compared for the 13 X-ray systems by using acrylic plates (20-cm thick) and a skin dose monitor. The X-ray conditions used in the measurements were those normally used in the facilities performing percutaneous coronary intervention.

The average surface dose for systems from three different vendors producing conventional fluoroscopy systems was 23.93+/-2.77 mGy/min vs. an average surface dose of 22.52+/-4.50 mGy/min from five vendors of pulsed fluoroscopy systems (25, 30, and 50 pulses/sec) (P=0.646). The average entrance surface dose was significantly (P<0.0001) higher with conventional fluoroscopy and pulsed fluoroscopy at 25, 30, and 50 pulses/sec (23.05+/-3.78 mGy/min) than with pulsed fluoroscopy at 15 pulses/sec (13.86+/-3.22 mGy/min).

Pulsed fluoroscopy did not in itself reduce radiation exposure. In general, the use of pulsed fluoroscopy at a pulse rate lower than 25 pulses/sec should reduce the skin dose in fluoroscopically guided intervention procedures. Nevertheless, some X-ray systems are not designed to reduce the dose rate as the number of pulses per second is decreased. Physicians should be aware of the entrance surface dose of the X-ray system that they use for cardiac IVR.