C-arm Radiation Safety at Tufts
Required RS Training Info What are annual rad. dose limits? Who is our regulator? What should you do in an emergency? Are there health effects of radiation? C-arm beam awareness info
Radiation Safety MA Law requires that persons who use radiology equipment be adequately trained in equipment operation and radiation safety principles. i [Get specific equipment training i in addition to this general awareness session.]
Authorization to take a radiograph at Tufts Clinical radiology examinations must be ordered by a Tuft s Physician, i or authorized health care provider. The unit requires registration with MA Radiation Control Program & operators need RS training.
Restricting Access to X-ray Rooms Allow no unauthorized visitors during x-ray exams. It is Tufts policy, that t no minors operate x-ray equip t. MA Law states that only individuals required for the radiographic procedure shall be in the radiographic room during exposures; and except for the patient, no unprotected body parts of their bodies shall be in the useful beam.
Fluoroscopy equipment Fluoroscopy delivers a dose of approximately 5 Rads per minute in the direct beam. Exposure to the operator s hands, even with a mini C-arm, can be high. Keep your hands out of the primary radiation. We should NOT see the fluoroscopist s hands or fingers on the fluoro images. Compare this to the 2 mrad/hour maximum for unrestricted areas.
Fluoro equipment continued Use the low dose equipment option whenever possible. [more noise level of the image, but much less dose to the operator.] Ensure fluoro is energized only when actively looking at the fluoro image. Use of intermittent fluoro reduces operator exposure [ That is, start and stop fluoroing, using pulses of radiation, rather than using it continuously. This can cut operator dose in half.] Use the last image hold feature to further reduce radiation exposure. [ex. When studying anatomy or needle placement, stop the fluoro and study the last image on the monitor.]
What Else Can You Do? Close collimation reduces and staff s exposure dose. Scatter radiation is MUCH lower for smaller field sizes. [Close collimation improves image contrast as well.] Avoid fluoroing at the edge of the patient. Primary radiation hitting the table [i.e. not going through the patient] results in more and higher energy scatter radiation, and results in higher doses to the fluoroscopist and others present.
Technical Factors Kvp must be appropriate for the study. For C-arms arms, typically the kvp and ma are adjusted automatically. Note at higher kvp, the scatter radiation is more penetrating. Do not override and use kvp much higher than needed.
Prior Radiograph Viewing Viewing prior radiographs, especially for orthopedic studies, can dramatically reduce the repeat rate for radiographs and fluoro time required for procedures. Whenever possible, view original orthopedic radiographs before performing a fluoroscopic examination.
Lead aprons to protect staff All workers in the x-ray room during studies must have a lead apron. Keep the lead between you and the x-ray tube. That is, do not turn your unshielded back to the x-ray tube. Use of wrap around style aprons can help. Lead gloves are required if hands are in the primary beam. Thyroid shields are needed for fluoro as well.
Question??? How much lead equivalent must be in an apron used during fluoroscopy?
Wear a lead apron during fluoro 0.5 mm lead equivalent for fluoro aprons - wrap around style aprons are best for persons who need to move about in the room.
Just how protective are lead aprons? It depends on the condition of the apron, and the operating factors of the C-arm. But in general for scatter radiation [not primary] from a C-arm set at 100 Kvp, 3.2% of the radiation is transmitted. If the unit is set at 70 kvp, only 0.36% is transmitted. 1 1. Yaffe, MJ Health Physics 1991
Before you put on that apron Look at the label verify it is 0.5 mm lead equivalent Look at the condition of the apron if it is visibly in poor condition, request a different one Is it one of the old rigid types? These can be so inflexible as to cause gaps which expose breast tissue etc. when they do not mold to the body. Insist on a well fitting apron Weight of the aprons varies. A 0.5 mm apron can weigh from g p p g 5 to 15 pounds, depending on the actual composite material. If you have back problems or for long procedures, select the lightest 0.5 mm equiv. apron available
Thyroid Shield Use of a thyroid shield keeps worker s radiation dose ALARA [as low as reasonably achievable.]
Lead Shield Care Hang aprons and shields on racks. Do not bend or fold lead aprons or shields. Folding can cause cracks and tears in the protective material. Periodically inspect shields for evidence of damage. Remove damaged ones from use.
Lead glasses For persons who routinely fluoro for long or interventional procedures, lead glasses with side shields can provide additional protection to the lens of the eyes. Note that the operator often has to look sideways from the C-arm x-ray tube to see the image on the monitor. This leaves the lens unprotected if glasses do not have side shields.
C-arms Best Orientation What position of the C-arm results in less higher energy backscatter radiation exposure to the head and upper body of the unit operator? X-ray tube DOWN [and Image Intensifier as close to patient as feasible.]
Where to stand for angled imaging Observers should stand on the Image Intensifier side of the C-arm whenever possible, to avoid the leakage radiation from the x-ray tube. Step back from the patient as much as possible. Stepping even one foot further back can significantly reduce one s dose.
Reporting problems Remove from service any x-ray equipment that appears to be malfunctioning. Contact your supervisor and repair personnel. Do not use x-ray equipment that is clearly malfunctioning.
Radiation Biology Even small doses of radiation can damage DNA. DNA damage can lead to cancer. One rad = ~ one chance in 100,000 Very large doses of radiation [>100 Rem] can cause acute health effects.
Typical Large Patient Doses for Common Exams skin entrance doses PA Chest AP Abdomen Head CT Knee Shoulder Lat skull Fluoro 10 mrem 325 mrem 2000 mrem 20 mrem 25 mrem 70 mrem 1000-4000 mrem/min. [For human patients, t keep tube at least 12 inches, prefer 15, from their body. Severe patient injuries have occurred, ex. when pt arm accidentally directly on x-ray tube, during a long fluoro. Arm was covered by drapes and not noticed.]
ALARA As Low As Reasonably Achievable Using good safety practices each day, every study, to keep your and your patient s radiation dose as low as feasible. ALARA is required by law.
MA DPH Occupational Dose limits MA Dept. of Public Health, Radiation Control Program MA has annual al worker dose limits to ensure worker safety. Goal to be as safe as other safe occupations. Whole body limit - Extremity limits - Lens of eye limit - 5000 mrem/yr [or 5 Rem/yr] 50,000000 mrem/yr 15,000 mrem/yr Typical Doses to Rad. Techs - < 100 mrem/yr whole body Fluoroscopists and Nuc. Med. Techs can be somewhat higher, but usually still well below the 5 Rem/yr
Radiation Badges All badges are NVLAP certified to ensure maximum accuracy of the dose report. Wear the badge flat against your body at your neck. [Unless you are pregnant and issued a waist badge also.] Do not wear badges on a chain, which would allow the badge to turn at various angles as you work. Turn in the badge for processing at the end of the monitoring Turn in the badge for processing at the end of the monitoring period. The badges must be sent to the vendor for processing.
Remember to: Wear only your own badge Wear it whenever working at Tufts Univ. Leave it in a cool, dry place away from radiation when not in use Do not take your badge home. Do not launder the badge or get it wet. Do not expose to heat, such as in a car in summer. Do not open badge. Do not expose the badge to other sources of radiation. Do not wear the badge for personal x-ray or nuclear medicine exams. Turn in your badge for processing in a timely manner. Please cancel badge service when no longer needed.
Pregnant Radiation Workers Declared Pregnant Rad. Workers must be limited it to 500 mrem/9 months. Tufts goal is to have the exposures < 50 mrem/ 9 mos. Extra badges to wear at the waist are available to pregnant radiation workers who elect to declare their pregnancy. Declaration of pregnancy is voluntary.
Maternity aprons not commonly used For radiologists or others who frequently fluoro and are pregnant, maternity aprons can be obtained. These have extra lead in the area of the abdomen. [not as heavy as an overall 1 mm lead apron would be] One can make their own by affixing extra lead to an apron, ex. lead blocker from Radiology Dept.
Controlling External Exposure Time, Distance & Shielding
Time make sure the fluoroscopist knows the total fluoro time-only required people should be present Use intermittent fluoro and last image hold methods
Distance - stand as far away from the patient during fluoro as feasible. When not assisting, stand at least one meter from the patient.
Shielding 0.5 mm lead equivalent apron, Wear a thyroid shield, Wear lead gloves if hands will be close to or potentially in the beam, Lead glasses for those who frequently fluoro for long, interventional procedures
Another Important t Safety Issue - Needle Safety Common causes of accidents - Use one hand technique if feasible. That is, keep your other hand away from the needle. Be sure you have enough light and can see what you are doing. Dispose of used needles properly immediately after use.
Needle sticks Report needle sticks and get medical evaluation. Use safety needles or canulas whenever feasible. Tufts Campus Police can assist you with any injuries i or incident id reports.
For Further Information Contact : Your supervisor or the Tufts Office of Environmental Health and Safety at 617-636-3450