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Pulsed fluoroscopy is a technique in fluoroscopic imaging where X-rays are emitted in short pulses (frames per second) rather than continuously. This reduces radiation dose to the patient and staff while maintaining adequate image quality for diagnostic and interventional procedures.

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![Fluoroscopic pulsing X-rays are produced during a small portion of the video frame time: The pulse rate may be reduced by skipping video frames with the constraint that the video frame rate must be an exact multiple of the pulse rate to retain synchrony between the X-ray pulses and the video frame acquisition. In the U.S., the video frame rate is 30 frames per second. Thus, X-ray pulse rates of 30, 15, 7.5 frames per secondare feasible. The temporal relationships between X-ray pulsing and video framing are shown. Visual flicker would be apparent at pulse rates below 30 pulses per second. This phenomenon is reduced by repeatedly displaying the last image at the full video frame rate (30 frames per second). FPS = frames per second.

Hirshfeld JW, Balter S, Brinker JA, et al. ACCF/AHA/HRS/SCAI clinical competence statement on physician knowledge to optimize patient safety and image quality in fluoroscopically guided invasive cardiovascular procedures. Journal of the American College of Cardiology. 2004;44(11):2259-2282. doi:10.1016/j.jacc.2004.10.014](attachment:c4639191-db10-446f-8d2e-fde7c7712b92:image.png)

Fluoroscopic pulsing X-rays are produced during a small portion of the video frame time: The pulse rate may be reduced by skipping video frames with the constraint that the video frame rate must be an exact multiple of the pulse rate to retain synchrony between the X-ray pulses and the video frame acquisition. In the U.S., the video frame rate is 30 frames per second. Thus, X-ray pulse rates of 30, 15, 7.5 frames per secondare feasible. The temporal relationships between X-ray pulsing and video framing are shown. Visual flicker would be apparent at pulse rates below 30 pulses per second. This phenomenon is reduced by repeatedly displaying the last image at the full video frame rate (30 frames per second). FPS = frames per second.

Hirshfeld JW, Balter S, Brinker JA, et al. ACCF/AHA/HRS/SCAI clinical competence statement on physician knowledge to optimize patient safety and image quality in fluoroscopically guided invasive cardiovascular procedures. Journal of the American College of Cardiology. 2004;44(11):2259-2282. doi:10.1016/j.jacc.2004.10.014

Principle

• In continuous fluoroscopy, X-rays are generated constantly.
• In pulsed fluoroscopy, the X-ray tube emits radiation only during discrete pulses, synchronized with image acquisition.
• Typical pulse rates: 3, 7.5, 15, or 30 pulses per second (pps).
• Lower pulse rate = lower dose, but may reduce temporal resolution.

Technical Aspects

• Achieved by rapid on–off switching of the X-ray tube current using high-frequency generators.
• Images are displayed at standard monitor frame rates (25–30 fps), with intermediate frames filled by last-image-hold (LIH).
• Combined with dose-saving features like automatic exposure control (AEC), last-image-hold, and collimation.

Advantages

1. Radiation Dose Reduction: Dose is proportional to pulse rate; reducing from 30 pps to 7.5 pps can cut dose by >70%.
2. Reduced Motion Blur: Short exposure per pulse (few milliseconds) → sharper images of moving structures (catheters, contrast bolus).
3. Improved Image Quality vs Continuous Low-Dose Mode: Preserves contrast and spatial resolution.
4. Integration with Digital Subtraction Angiography (DSA): Pulsed mode is essential for high-quality vascular imaging.

Disadvantages / Limitations