Interventional radiology(IVR)procedures may involve high radiation doses that are potentially harmful to the patient. In IVR procedures. pulsed fluoroscopy can greatly decrease the radiation that the physician and patient receive. There are two types of pulsed fluoroscopy : direct control and primary(indirect)control. The purpose of this study was to compare pulsed fluoroscopy by direct control, using a grid-controlled x-ray tube, with pulsed fluoroscopy using primary control. For both types of pulsed fluoroscopy, we measured the waveforms(x-ray tube voltage, x-ray tube current, and x-ray output)and the relative radiation dose. In addition, we compared the decrease in radiation during pulsed fluoroscopy using a care filter. The studies were performed using a Siemens Bicor Plus x-ray System(direct control)and a Siemens Multistar Plus x-ray System(primary control). Using primary pulse control, a 50% decrease in the x-ray output waveform took approximately 0.5-1.0 msec, or longer with a lower x-ray tube current. Using direct pulse control, a 50% decrease in the x-ray output waveform took approximately 0.1 msec, and was independent of x-ray tube current. The rate of radiation reduction with primary pulse control using the care filter with a lower x-ray tube current had a slope exceeding 10%. Pulsed fluoroscopy by direct control using a grid-controlled x-ray tube permits an optimal radiation dose. To decrease the radiation in primary pulse control, a care filter must be used, particularly with a lower x-ray tube current.
