Radiation Safety for C-Arm and Mobile X-Ray Systems

Mobile C-arm fluoroscopy units and portable X-ray systems bring imaging capability directly to the operating room, ICU, and ward — but they also bring an ionizing radiation source into close proximity to patients and staff, often repeatedly throughout a working day. This article summarizes internationally recognized radiation safety principles for using refurbished C-arm and mobile X-ray systems, with practical guidance for biomedical engineers, radiographers, surgeons, and administrators.

The ALARA Principle in Fluoroscopy and Radiography

As with ultrasound, the guiding principle for ionizing radiation is As Low As Reasonably Achievable (ALARA). The FDA advises that fluoroscopy should always be performed with the lowest acceptable exposure for the shortest time necessary to achieve the clinical goal, since fluoroscopic procedures — especially complex interventional cases — can deliver relatively high cumulative doses (FDA, Fluoroscopy). ALARA does not mean avoiding necessary imaging; it means eliminating exposure that provides no additional diagnostic or procedural benefit.

Practical ALARA Techniques for C-Arm Use

1. Minimize fluoroscopy time — use short bursts and last-image-hold instead of continuous live fluoroscopy whenever the clinical task allows.
2. Use pulsed fluoroscopy at the lowest acceptable frame rate rather than continuous mode, since lower pulse rates substantially reduce dose while typically preserving adequate image quality for many procedures.
3. Avoid unnecessary magnification — reducing the field of view (magnification) can increase dose rate by a factor of four for a factor-of-two reduction in field size, according to interventional radiation-safety training materials used in clinical cath-lab settings.
4. Position the image intensifier/detector as close to the patient as possible, and keep the X-ray tube as far from the patient as the equipment allows, since dose falls off rapidly with distance from the source.
5. Collimate tightly to the anatomy of interest — smaller field size reduces both patient dose and scattered radiation to staff.
6. Step back or use maximum practical distance from the beam and patient during exposures whenever the procedure allows, since staff dose from scatter drops sharply with distance.

Occupational Dose Limits: What Biomedical and Clinical Staff Should Know

Radiation protection agencies publish annual occupational dose limits that hospitals should use to guide monitoring programs and shielding decisions.

Actual measured doses for interventional staff using good practice are typically far below these limits — cath-lab monitoring data show most nursing and radiology staff receiving well under 5 mSv per year when shielding and technique are followed correctly (Belgian FANC cath lab training slides). These limits are ceilings, not targets — ALARA requires facilities to stay as far below them as reasonably possible.

Personal and Structural Shielding

Source: Belgian FANC cath lab radiation protection training; Stanford EH&S guidance.

Personal Dosimetry Program

• Any staff member with reasonable potential to exceed regulatory monitoring thresholds (commonly around 10% of the annual occupational limit) should wear a personal dosimeter (film badge, TLD, or electronic dosimeter) (Stanford EH&S, Dosimetry).
• Dosimeters should be worn at collar level outside the lead apron to estimate effective dose and unshielded exposure, with a second dosimeter under the apron in some interventional programs for dual dosimetry.
• Review dosimetry reports on a defined cycle (commonly monthly or quarterly) and investigate any reading that exceeds facility-defined investigation levels, even if below the regulatory limit.
• Maintain dosimetry records long-term, since cumulative lifetime dose tracking is part of several national frameworks.

Pre-Use and Periodic Checks for C-Arm/Mobile X-Ray Systems

Staff Positioning and Workflow Practices

• Whenever possible, staff not directly performing the imaging task should step outside the room or behind a shield during exposures.
• Use the C-arm's remote or extended footswitch cabling to allow the operator to stand farther from the beam.
• Rotate staff assignments for high-frequency fluoroscopy procedures to distribute cumulative dose across the team where appropriate.
• Post radiation area warning signage at room entrances per facility and national regulatory requirements.
• Ensure pregnant staff are aware of declaration procedures and additional protective measures available to them.