Fluoroscopy is indispensable in the modern OR. It is also a source of ionizing radiation exposure for both patients and surgical teams — and unlike diagnostic radiology, where a radiologist reviews images from outside the room, fluoroscopy involves staff who stand adjacent to the patient and C-Arm during active imaging. Managing radiation dose in fluoroscopy is not a regulatory checkbox; it is a practical daily concern for surgeons, technologists, and OR nurses who perform fluoroscopic procedures repeatedly throughout their careers.
ALARA: The Governing Principle
ALARA — As Low As Reasonably Achievable — is the principle that guides radiation protection in medical fluoroscopy. It means that dose should be minimized to the extent possible without compromising the diagnostic or procedural quality needed to safely complete the case. ALARA is not a specific dose target; it is a framework for decision-making that applies at every step of a fluoroscopic procedure: choosing when to acquire versus when to use last image hold, selecting the appropriate dose rate mode, minimizing beam-on time during non-critical procedure phases, and using collimation to reduce the field size to the region of clinical interest.
Continuous vs. Pulsed Fluoroscopy
Continuous fluoroscopy delivers X-ray output without interruption while the foot pedal is depressed — typically 30 frames per second. It provides the smoothest real-time motion display but at the cost of the highest continuous dose rate. Pulsed fluoroscopy delivers X-ray pulses at a reduced frame rate — commonly available at 15, 7.5, 3, or 1 pulse per second — with the display interpolating between pulses to maintain a watchable image. At 7.5 pulses per second, dose rate is typically reduced by 50 to 75 percent compared to continuous fluoroscopy, with no meaningful loss of procedural guidance for most surgical applications.
Modern C-arm systems like the GE OEC Elite CFD and Philips Zenition 70 offer multiple pulsed dose rate modes and allow the operator to step down to lower pulse rates for the navigational phases of a procedure while stepping up for critical imaging moments. Developing a protocol-based approach to dose rate selection — starting at a low pulse rate and escalating only when needed — rather than defaulting to continuous or high-rate fluoroscopy is one of the highest-impact dose reduction behaviors available to the surgical team.
Last Image Hold and Fluorostore
Last image hold (LIH) retains the most recent fluoroscopic frame on the display after the foot pedal is released. Instead of re-exposing to confirm the current anatomy or implant position, the surgeon can review the last frame, make adjustments, and only re-expose when the situation has changed enough to require a new view. Used consistently, LIH can reduce fluoroscopy time by 20 to 40 percent compared to teams that continuously fluoro throughout a case.
Fluorostore, available on GE OEC systems, retains a replay loop of the most recent fluoroscopic sequence — not just the last frame, but the last several seconds of fluoroscopy. This is clinically valuable for dynamic assessments: confirming a wire passed a target point, watching contrast fill a vessel segment, or reviewing a device deployment sequence. Reviewing stored fluoroscopy eliminates the need to re-expose to see a motion event that already occurred.
Collimation, Distance, and Positioning
Collimation — restricting the X-ray beam to the region of clinical interest using the adjustable shutters built into the C-Arm — reduces dose to the patient by exposing only the anatomy being imaged. It also reduces scatter radiation, which is the primary source of radiation dose to the surgical team. Reducing the irradiated field by half reduces patient dose and scatter by roughly 50 percent.
Distance from the X-ray source follows the inverse square law: doubling the distance from the source reduces dose to one quarter. The primary source of dose to the surgical team is scatter from the patient, not direct beam — and scatter originates at the patient surface closest to the X-ray tube. Positioning the tube below the table (tube-under technique) places the primary scatter downward, away from the surgeon standing at the table. When the tube is above the patient, scatter from the patient surface is directed upward toward the surgical team, significantly increasing their exposure.
Bottom Line: Radiation dose management in fluoroscopy is a technical and behavioral practice. The most impactful steps — using pulsed fluoroscopy at the lowest effective rate, using LIH and fluorostore to reduce re-exposure, collimating aggressively, and positioning the tube below the table when possible — are available on any modern C-arm system. The technology matters, but so does how the team uses it.
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