Techniques for C-arm dose reduction in everyday surgery

Start with the principles: time, distance, shielding

The ALARA principle (as low as reasonably achievable) is best applied as three questions: can I use less time, more distance or better shielding? Fluoroscopy time is the most controllable factor; every second of beam adds dose, so the cheapest reduction is simply not to expose when no one is looking at the monitor.

Dose to staff falls rapidly with distance from the patient, who is the main source of scatter. Step back when you can, and use the barriers described in our guide to radiation protection equipment.

Pulsed fluoroscopy and the C-arm low dose mode

In pulsed fluoroscopy the beam is delivered in short pulses instead of continuously. Lowering the pulse rate, for example for slow-moving anatomy, reduces dose roughly in proportion, with a modest effect on temporal smoothness. For most orthopaedic, spine and pain procedures a low pulse rate is perfectly adequate.

A C-arm low dose mode reduces tube output or applies more image processing to maintain visibility. The Villa Arcovis DRF-C offers High-Quality, Low Dose, Peak Opacification and Snapshot modes, selectable from a multifunction foot pedal, while the Perlove PLX C1112 provides automatic and pulsed fluoroscopy with automatic kV/mA tracking to balance image quality and dose. Use the lowest quality setting that still lets you do the task.

Collimation, geometry and last image hold

Collimation narrows the beam to the area of interest, which both reduces dose and improves contrast by cutting scatter. Adjust the collimator on the last image hold, not on live beam. The last image hold function keeps the final frame on screen so the surgeon can think, point and plan without further radiation.

Geometry matters as well: keep the tube as far from the patient as practical and the detector as close as possible, and avoid steep oblique angles when a less oblique one is sufficient, since both increase patient entrance dose. Avoid magnification modes unless the detail is needed, as they raise dose.

• Detector close to patient, tube below the table
• Collimate on last image hold
• Use the lowest pulse rate that works
• Avoid unnecessary magnification
• Save images instead of repeating exposures

Laser aiming and remote exposure

Laser localisers allow you to centre the beam on the target before any radiation is used. The Perlove PLX C1520/1521 has laser positioning on both tube and flat panel, and the Arcovis DRF-C has dual laser localisers. Used consistently, they remove many exploratory exposures.

Remote exposure, as on the PLX C1520/1521, lets the radiographer operate the system from a protected position when sterile access is not needed. Our positioning guide describes how to position the arc efficiently.

Monitoring dose and building a culture

A dose-area product (DAP) display and recorded dose reports let teams see how their habits translate into numbers. Review them in audits and train new staff on the settings above. Include dose in the induction of any new C-arm, and discuss it with your radiation protection officer; see radiation safety guidance.

Beckfinity's specialists can provide application training with new equipment and advise on options such as DAP meters and laser localisers for the PLX C1520/1521 or the Arcovis DRF-C. Contact us to request a quotation.

It is useful to review dose figures by procedure type once a quarter in a team meeting, comparing surgeons and units without looking for blame. This reveals habits worth changing and settings worth fixing in protocols.