◙ DOSE OF REALITY There are several steps you can take to reduce radiation exposure.

While preparing a presentation about C-arm safety for a gathering of pain management physicians, I asked the course director how aggressive the message should be. "Very," he said, before removing his jacket to reveal the telltale scars of chronic radiation exposure on both arms in addition to his nose. During a hands-on training session later that day, I noticed he administered injections with the C-arm aimed across the table, exposing his hands and the tip of his nose to the raw X-ray beams traveling above the patient. The experience confirmed what I already knew: Radiation exposure is a very real, but often overlooked, danger during all fluoroscopic procedures.

1 Focus on basic precautions
Healthcare professionals who work imaging procedures should understand the principles of administering doses As Low As Reasonably Achievable (ALARA). But that C-arm safety mantra may not be enough to protect patients and staff from harm.

Keep your hands out of the X-ray beam unless there's a compelling medical reason to do otherwise. Procedural convenience is not a compelling reason, regardless of what your surgeons might claim. Sounds obvious, but na??ve or careless physicians continually ignore this straightforward advice. In fact, it's the most common mistake I see during imaging cases.

Some physicians remove the C-arm's X-ray tube spacer in order to simplify rotation of the machine. Dose rates under these conditions can be several 10s of rads per minute with standard C-arm fluoroscopes and are also heightened with mini C-arms. The spacers are on the units to protect patients from excessive skin doses. Don't remove them!

2 Assume proper positions
The amount of radiation surgical teams and patients are exposed to during procedures depends on the position of the C-arm. Place the X-ray tube underneath the patient. Positioning the X-ray tube above the patient is often an issue with hand and foot surgeons, who like to use the image intensifier as an operating surface. This isn't a recommended practice, but surgeons who have good clinical reasons to use the image intensifier as a patient support must always wear proper eye protection and focus on keeping their hands out of the raw X-ray beam.

Also, place the image intensifier as close to the intended imaging site as possible. This will keep the X-ray tube far from the patient. Many surgeons wrongly move the image intensifier away from the patient in order to gain more room to operate.

Stand near the image receptor side of the C-arm. Most of the radiation that reaches staff bounces off patients and back toward the X-ray tube. On a typical C-arm, there's 5 to 10 times more radiation on the X-ray tube side than on the image intensifier side. When you stand on the X-ray tube side, the patient is your source of radiation; on the image intensifier side, the patient is part of your protection system.

Remain vigilant when positioning C-arms over patients. In one facility, according to a report in the journal Anesthesia & Analgesia, the lower half of a C-arm wedged onto the floor control of an operating table when the unit was moved into position. The table tilted uncontrollably before the surgical team noticed the issue and removed the arm from the floor control. Their quick thinking saved the patient from a potentially tragic fall.

3 Image judiciously
Surgeons must capture images that let them see enough to work confidently. The highest dose rates that the machines can produce are seldom a clinical necessity. In addition, C-arms should be activated only when there will be immediate use of the images.

Physicians must understand the importance of limiting exposure risks, and activate the C-arm only when they're looking at the X-ray monitor. They can't forget they're still activating the X-ray as their attention shifts to the procedure's next step. It's estimated that 10% to 20% of all radiation is wasted in this manner. Remember: The room is safe as soon as the surgeon takes his foot off the pedal.

By FDA mandate, all fluoroscopes manufactured since 2006 have "last image hold" features, which freeze the pictures captured when physicians lift off the foot pedal. Many mid-grade and high-end models also feature "fluoro loop," which cycles through the previous 10 to 15 seconds of captured images. Physicians should use these replay modes in place of live fluoroscopy whenever possible.

Recent fluoroscopes display the dose used during the procedure as well as the fluoroscopic time. It makes sense to record these values for every procedure and include this data in a formal quality assurance program.

DOSE DATA
Radiation Exposure Limits

Under most circumstances, the surgical team's exposure should not exceed 10% of ALARA's annual thresholds.

	MPD* (mrem/year)	ALARA† (mrem/year)
Whole body (head, trunk, arms above elbows, legs above knees)	5,000	500
Extremities (arms below elbows, legs below knees)	50,000	5,000
Individual organs, skin	50,000	5,000
Lens of the eye	15,000	1,500
*MPD = maximum permissible dose
†ALARA = as low as reasonably achievable

Source: Adapted from the National Council on Radiation Protection and Measurement's recommendations.

4 Wear proper protection
Staff members and physicians who routinely take part in imaging procedures must wear lead aprons and thyroid collars. The recommended weight of the apron depends on how busy you are around C-arms. Consult with your medical physicist or radiation safety officer, who can reference the radiation badge you wear to determine your average monthly exposure and recommend the appropriate apron. (Hint: Routinely wearing a badge may document a low enough dose to allow you to wear a lighter apron.) However, the required minimum thickness varies from state to state, so check your local regulations to determine which aprons are legal.

As a general guide, the International Commission on Radiological Protection says an apron with 0.35mm lead-thickness equivalence is sufficient for most fluoroscopic procedures. Staff and physicians with heavier imaging workloads should wear wrap-around lead aprons that overlap at the front with 0.5mm lead-thickness equivalence. Individuals with light imaging workloads receive adequate protection from 0.25mm lead-equivalence aprons.

Inspect aprons regularly and before use, palpating the surfaces and looking for tears. Hang them in storage so they don't bend or crack. Many states require formal annual inspections, which may involve X-raying each apron to ensure they're still intact.

Over the past few decades, experts have learned that healthcare providers who are regularly exposed to X-rays are more likely to develop cataracts than the general public, so anyone who routinely touches patients while the X-ray is activated should wear lead glass eyewear.

5 Track exposure
All those involved in fluoroscopy procedures who wear lead aprons must also wear 2 radiation badges: one under the lead apron between the waist and chest, along the midline; the other on top of the apron at the left side of the collar (usually closer to the X-ray tube) in order to measure eye exposure, according to National Commission on Radiation Protection & Measurements guidelines.

◙ HANDLE WITH CARE Hang lead aprons in storage so they don't bend or crack.

Radiation safety officers use the combined readings to estimate the whole body dose, typically on a monthly basis. The badges indicate if members of the care team are wearing enough protection, and help determine if the protection is working properly. Maximum acceptable exposure levels are based on NCRP recommendations (see "Radiation Exposure Limits"). Under most circumstances, the surgical team's exposure should not be more than 10% of these limits (shown as the ALARA values in the table). A final note: Be wary when an individual's badge always indicates zero radiation exposure. The person assigned to wear that badge may not be doing so.

6 Safeguard the room
C-arms should be used in rooms large enough so that staff members not involved in the procedure can retreat to safe distances (typically beyond 6 feet from the radiation source). Keep doors closed during imaging procedures so unprotected and unaware staff members don't wander in. Your local regulations will dictate if the walls and doors of an OR used routinely for imaging cases need to be leaded for added protection. If possible, hang electronic signs in imaging rooms that indicate when the X-ray is activated — some C-arms have a circuit that would activate the external light.