SET THE STAGE The positioning and settings of a C-arm can significantly reduce the risks of radiation exposure to patients, users and staff.

Fluoroscopic imaging plays a key role in orthopedics, spine surgery and pain management procedures, and mobile C-arms are a fixture in many outpatient ORs. But these radiological devices are not point-and-shoot by any means. To ensure their safe use, and the safety of your personnel and patients, keep compliant with these 5 factors.

1. Qualified operation
There are no national regulations concerning the use of fluoroscopic equipment, and radiation protection rules vary from state to state.

"In some states, the certification of the operator is mandatory, such as in Texas and California," says Richard L. Morin, PhD, a professor of radiologic physics at the Mayo Clinic in Jacksonville, Fla., as well as the chair of the American College of Radiology's Dose Index Registry and co-chair of the "Image Wisely" initiative (imagewisely.org). "But most often it is the facility that sets the rules."

No matter their size, facilities must maintain the same standards as large hospitals or academic institutions, says Dr. Morin. The C-arm's operator must be trained and certified in radiation safety, and facilities must appoint an in-house staffer or an outsourced consultant to the position of radiation safety officer. "This person is responsible for ensuring that safety protocols are being followed," says Jason Launders, MSc, a researcher at the ECRI Institute in Plymouth Meeting, Pa. They also monitor employees' exposure, manage the equipment's service and inspection, and educate staff.

2. Proper positioning
Equipment positioning influences exposure risks. Most C-arms are built to place the X-ray tube under the patient for a reason. "If the tube is above and the detector beneath, you're potentially exposed to 100% of the backscatter," says Dr. Morin. "If the tube is beneath the patient, you only get 1%."

Plus, the scattered radiation, which comes not from the tube but from the patient, and which is not reflected like light but diffused in all directions — "Imagine a patient glowing X-rays," describes Mr. Launders — emerges primarily from the side of the body where it went in.

Positioning can help to minimize the radiation dose delivered to the patient's skin. "You want to have the radiation source as far away from the patient as possible, and the area you're imaging closer to the detector," says Garrick Cason, MD, an orthopedic surgeon and clinical instructor at the University of Tennessee at Chattanooga. This can also produce higher-quality images.

"Position the beam perpendicular to the place you want to image," says Dr. Cason, "and avoid steep angles. Those cross through more of the body," causing the device to deliver more radiation.

A BATCH OF BADGES Dosimeter badges are a consistent record of cumulative exposure.

3. C-arm settings
"Every hospital I've ever been in practices ALARA — 'as low as reasonably achievable,'" says Dr. Cason. "That's the mantra of everyone who's participated in a radiation safety program." Common C-arm settings can optimize radiation doses to deliver quality images from the lowest amounts.

Collimation narrows the beam and limits the size of the field, reducing exposure. "You should collimate to just the part that you want to see," says Dr. Morin. "A larger field is just more scatter. Cone it down, and you'll also increase image quality."

He also recommends working from still images. "Make sure the system has a last-image-hold function," he says. "A quick shot can provide a high-quality image, then you can examine what you see without beam-on time."

When it's necessary to track motion, though, Dr. Cason recommends using pulse fluoroscopy. Real-time views from 4 exposures a second significantly reduce the device's radiation emissions.

4. Shielding and distance
Radiation exposure presents 2 risks, depending on its amount and duration. Deterministic effects such as skin burns, radiation sickness and cataracts can result from a high dose received over a short period. Stochastic effects such as cancer or genetic mutations are cumulative, resulting from multiple exposures over the long term. Just because surgical personnel won't see stochastic effects right away doesn't mean they're not at risk.

"Lead aprons and standing at a distance are the only ways for staff to mitigate exposure," says Mr. Launders. Aprons (or vests and skirts) and thyroid shields incorporating a 0.5mm lead-equivalent material are a must for users and bystanders alike. Leaded goggles (or glasses with side shields) and gloves add protection for those at the table. While mobile C-arms render fixed shields impractical, leaded glass screens on rollers and lead-lined table drapes that block scatter from beneath may work.

If there's nothing to stand behind, though, just stand back. "Understand that distance is your friend," says Dr. Cason. "Distance exponentially decreases your exposure. If you're not actively involved in the case, all you need is 6 feet."

5. Monitored exposure
In addition to protective garments, those present during C-arm use must also wear a dosimeter film badge outside their clothing to monitor the cumulative amount of radiation the unprotected parts of the body receive. Regularly ship used badges to the manufacturer for monitoring.

"The film badge is the legal record, the best way to track exposure," says Mr. Launders. "Keeping track of badges is not trivial."

Ask new hires where else they've worked with radiation to update their lifetime exposure statistics, says Dr. Morin. If staffers moonlight at other facilities where they're exposed to radiation, Mr. Launders recommends they take their badges along. If a staff member becomes pregnant, the radiation safety officer should re-evaluate their exposure risks. And dose information should be recorded in patients' charts.