Perceptual comparison of pulsed and continuous fluoroscopy

Area of Science:

• Medical Imaging
• Radiology
• Human Factors Engineering

Background:

• Pulsed fluoroscopy at reduced acquisition rates (e.g., 15 acq/s) is proposed to decrease X-ray dose during interventional procedures.
• The human visual system (HVS) acts as a temporal low-pass filter, influencing the perception of low-frame-rate fluoroscopy.
• Determining the appropriate X-ray dose for pulsed fluoroscopy requires perception experiments to match visualization quality with conventional continuous fluoroscopy (30 acq/s).

Purpose of the Study:

• To determine the X-ray dose for low-frame-rate pulsed fluoroscopy that provides visualization equivalent to conventional 30 acq/s continuous fluoroscopy.
• To evaluate dose savings achievable with pulsed fluoroscopy at various frame rates (15, 10, and 7.5 acq/s).
• To assess the impact of display type (interlaced vs. non-interlaced) and object size on dose equivalence and savings.

Main Methods:

• Utilized computer-generated phantoms with low-contrast disks and Poisson noise simulating fluoroscopic quantum noise.
• Employed a video tachistoscope for displaying image sequences with flexibility.
• Conducted three complementary experimental paradigms: paired comparison, minimum-contrast measurement, and four-alternative forced-choice detection.
• Compared pulsed fluoroscopy (pulsed) with continuous fluoroscopy (30 acq/s).

Main Results:

• Excellent agreement (approx. 3% average absolute difference in equivalent perception dose) was found between supra-threshold (paired-comparison, min-contrast) and detectability (forced-choice) experiments.
• No significant difference in perceived image quality or equivalent dose was observed between interlaced and non-interlaced display formats.
• Dose savings increased with larger disk sizes, showing a small dependence.
• Achieved average dose savings of 22% for pulsed-15, 38% for pulsed-10, and 49% for pulsed-7.5 acquisition rates.

Conclusions:

• Low-frame-rate pulsed fluoroscopy can achieve visualization equivalent to conventional continuous fluoroscopy with significant X-ray dose reduction.
• The chosen experimental methods reliably determined equivalent perception doses across different paradigms.
• Substantial dose savings are possible, particularly at lower frame rates and for larger object sizes, without compromising diagnostic visualization quality.