radiation protection

Image gently…

Step Lightly

Interventional radiology helps us save kids’ lives!But, when we treat patients, radiation matters! Children are more sensitive to radiation. What we do now lasts their lifetimes. Treat kids with care:
Step lightly on the fluoroscopy pedal.
Stop and child-size the technique.
Consider ultrasound or, when applicable, MRI guidance.
Steps for Radiation Safety in Pediatric Interventional Radiology
Plan, prepare and communicate.
Measure, record and review.
1. Equipment
1. Qualified medical physicist (i.e., one who is board certified in diagnostic radiological physics) consultation at equipment selection,set up, and in equipment maintenance and quality assurance (QA).
2. At equipment set up, medical physicist to measure the radiation output from the interventional fluoroscope. Both the maximum radiation output (for largest adult-size patients) and routine radiation output as a function of varying patient size to be measured and documented.
3. At installation, “child-size” angiographic protocols created, with dose reduction, appropriate lengths of runs, and different frame rates for slow vs. high flow, infant, small child and teenager sized patients
4. CT guided procedures: “child size” protocols for CT guidance, using as low an mA as possible
5. Dose recording and reduction technologies installed in equipment
2. Pre procedure consultation
1. Ask about previous radiation
2. Answer questions about radiation safety

3. During procedure:
1. Appropriate communication between in room personnel: Don’t be afraid to ask the necessary questions to ensure you are working as a team to keep the radiation dose as low as possible
2. Use US if possible
3. Plan and communicate in advance: plan number of runs, injection parameters, contrast, pump, digital subtraction angiography (DSA) frame rates and optimize patient position timing with anesthesia and the
radiologist carefully, so as to avoid improper or aborted runs and the need to repeat a run.
4. Lower the number of exposures: use flouro save when possible.
5. View and save images with last image hold, decreasing acquisitions/exposures as much as possible when that level of detail is acceptable.
6. Step lightly: tap on pedal and examine still image on monitor, minimize live fluoroscopic time
7. Position with fluoroscopy off
8. Use pulse fluoroscopy when possible. Use a low pulse rate rather than high pulse rates or continuous fluoroscopy; for example, decrease from 7.5 pulses to 3 pulses a second whenever possible.
9. Collimate tightly. Decreasing the area of patient exposure directly decreases patient dose. Collimate to avoid dose to the eyes, thyroid and gonads whenever possible
10. Minimize overlap of fields in repeated acquisitions
11. Decrease the dose rate setting to the lowest level that provides adequate image quality during either fluoroscopy or the recording of images.
12. Minimize use of electronic magnification. Use fluoroscopic zoom whenever possible instead. Switch back to zero magnification whenever possible.
13. Move table away from x-ray tube in both planes to maximize distance between source and patient. Maintain an appropriate source to table top distance throughout the procedure. This shall be no less than 15 inches at any time. Lower the image intensifier (or flat panel detector) as close to the patient as possible, to minimize patient to detector distance, while still allowing room for manipulation of needles, wires catheters. Remember these principles in the lateral position.
14. Avoid radiosensitive areas (breast, eyes, thyroid, gonads) when possible. Evidence on the need/advisability for shielding of areas outside of the beam is conflicting at present.
15. Audible periodic fluoroscopy time alerts during case. Acknowledge the cumulative timing device. A reminder of the elapsed fluoroscopy time can be given to the operator during the procedure.
16. Image acquisition limited only to needed (frames per second, lower dose protocols, magnification, length of run)
4. After procedure:
1. Review dose
2. Counsel if skin dose greater than or equal to 2 Gy or cumulative dose of greater than or equal to 3 Gy (NCI)
5. Education
1. All operators receive comprehensive training in radiation physics, biological effects and safety.
2. Ongoing yearly training after initial certification
3. Audit radiation doses for all operators
4. Specific feedback and additional training when needed
5. All operators and team members, including non-radiology users betaught, tested and credentialed in radiation physics principles,radiation biology and radiation safety.
6. Measurement and QA
1. Record available indications of patient radiation dose including DAP,cumulative air kerma, etc. If these indices of radiation dose are notavailable, record fluoroscopy time and an estimate of the total number of recorded images, so that patient dose could be estimated in the future if necessary.
2. Patient dose record (Medical Imaging Record)
3. QA measures: Participate in or support radiation awareness undertakings in your department
4. In house radiation dose database of patients, procedures and dose information
5. Review radiation dose database to flag patients with doses greater than 2 Gy for follow up
1. Notes to primary care physician about procedure, dose and possible short and long term effects.
2. Counsel patient and primary care to call if erythema develops at beam entrance site
3. Establish follow up procedures including skin examination at 30 days
4. Minimize cumulative dose over time for radiology operator and staff
1. Remember that reducing patient dose reduces scatter and dose to personnel also: they are tied together
2. Personal protective equipment:
1. Leaded eyewear
2. Well fitted lead apron
3. Thyroid shield
3. Use hanging lead shields to protect lower extremities and movable overhead shields for face and neck protection. Set up the room at the start of the case with lead table skirts and all shielding. Don’t be hesitant to remind the operator of their use.
4. When using lateral fluoroscopy, position personnel on same side as the image receptor/detector to decrease operator scatter dose from X-ray source
5. Step away during fluoroscopy or image acquisition if possible
6. Operator hands out of beam
7. Use power injector when possible. If hand injection, use extension tubing.
8. Distance: Advise the personnel in the room of the inverse square law (nurses, anesthesia, physicians)

Step Lightly Checklist
Review steps below before starting the procedure.
Safety is a team effort: don’t be afraid to ask the necessary questions to ensure you are working as a team to keep radiation dose to patients and staff as low as possible.
Reducing radiation dose must be balanced with safe, accurate and effective completion of the procedure. Not all the steps below may be possible in each case, depending on patient size, technical challenge and critical nature of the procedure. Overall patient safety is most important. The goal is to minimize the dose to the patient while providing important and necessary medical care.
• Ask patient or family about previous radiation (record card downloadable at this link). Answer questions about radiation safety (parent/patient brochure downloadable here)
• Use ultrasound when possible
• Position hanging table shields and overhead lead shields prior to procedure with reminders during the case as needed
• Operators and personnel wear well fitted lead aprons, thyroid shield and leaded eye wear
• Use pulse rather than continuous fluoroscopy when possible, and with as low a pulse as possible
• Position and collimate with fluoroscopy off, tapping on the pedal to check position
• Collimate tightly. Exclude eyes, thyroid, breast, gonads when possible
• Operator and personnel hands out of beam
• Step lightly: tap on pedal and review anatomy on last image hold rather than with live fluoroscopy when possible; minimize live fluoroscopy time
• Minimize use of electronic magnification; use digital zoom whenever possible
• Acknowledge fluoroscopy timing alerts during procedure
• Use last image hold whenever possible instead of exposures
• Adjust acquisition parameters to achieve lowest dose necessary to accomplish procedure: use lowest dose protocol possible for patient size,lower frame rate, minimize magnification, reduce length of run
• Plan and communicate number and timing of acquisitions, contrast parameters, patient positioning and suspension of respiration with radiology and sedation team in advance to minimize improper or unneeded runs
• Move table away from X-ray tube in both planes. Move patient as close to detector in both planes
• Use power injector or extension tubing if hand injecting
• Move personnel away from table or behind protective shields during acquisitions
• Minimize overlap of fields on subsequent acquisitions
• After procedure: record and review dose
Frequently Asked Questions – Medical Professionals
The amount of radiation that people are receiving from medical sources is increasing, and this includes children. It is difficult to show directly that radiation doses from CT lead directly to cancer. However, good data from other sources of exposure show that there are increased cancers in people who have been exposed to radiation at levels now encountered by patients undergoing CT scans. This is particularly important in children, whose tissues are more radiosensitive, who receive a larger effective dose for a given level of radiation, and who have a longer time to develop cancers resulting from radiation exposure. For any one person, the risk of death from cancer is about 1 in 5. While estimates vary, for a child undergoing a single CT of the abdomen and pelvis increases that risk by 1 in 1,000. The risk is cumulative, however, and each subsequent CT scan will increase the risk accordingly. While for any one individual the increased risk is very small, given the large number of CT scans performed the risk to the population as a whole is much larger.
Do children really undergo many CT scans?
The population of the United States is second only to Japan in per capita CT exams performed. There are approximately 7 million CT studies performed in children every year in the United States, and the number is increasing approximately 10% per year. CT is widely used among all ages of children, with 33% performed in children under 10 years of age. CT is the largest contributor to medical radiation dose in the United States.
Can the risk from CT be lessened while still obtaining diagnostic quality studies?
* Absolutely. There are many techniques that can be used to dramatically lessen the amount of radiation children are exposed to during CT, while still enabling diagnostic quality images (see also What Can I Do? Section). These include:
o Scan only the area required. Scanning beyond the body regions where there is clinical concern results in needless exposure.
o Reduce tube output (kVp and mAS). Exposure parameters should be reduced for the smaller patient size. A number of suggested protocols are available (LINK)
oPerform single phase studies. Most pediatric conditions are readily diagnosable with single phase CT; more phases unnecessarily increases radiation dose without adding to diagnoses.
oUse breast shields for girls undergoing chest CT studies.
Should I not order CT scans for my pediatric patients?
CT is an extremely useful imaging modality that can provide valuable and even life-saving medical information, and thus can provide more benefit than harm. Like any test, there should be clear reasons to order a CT scan. For many indications, a test like ultrasound or magnetic resonance imaging may provide the same information without exposing a child to radiation. The American College of Radiology (ACR) has imaging appropriateness criteria for a number of pediatric conditions and discusses the utility of various imaging strategies. Discussing the clinical situation and the medical information desired with the pediatric radiologists providing your imaging services can help determine if an alternative test might be better. If a CT scan is needed, make sure that your imaging facility uses appropriate radiation reduction protocols and techniques, and that those interpreting these pediatric studies are qualified.

How can I determine if my imaging providers are using appropriate CT techniques?
Without asking, you won’t know. Some facilities may not alter dose technique for studies on children. This website has published a straightforward method that can be implemented at your site with the help of a medical physicist. It is unique in that it does not depend on the manufacturer, model or age of the scanner. While there may be variability depending upon CT scanner manufacturer and institution, there are also a number of published suggested techniques that facilities can use that provide substantial dose savings. Similarly, most adult protocols call for scanning the same area several times (multiple phases); this is rarely required for pediatric conditions and results in needless additional radiation exposure.
Ask:
o if your imaging facility is accredited .
o if the CT technologists are credentialed
o if a board certified radiologist or pediatric radiologist will
be interpreting the study
Should I talk to parents about the risks involved in getting a CT?
The long-term risks of exposure to medical radiation are small but real. However, the diagnostic value that a CT can provide in the short-term usually far outweighs the long-term risks. Most patients are not informed of any potential risks from radiation prior to the exam (Lee CI, et al. Diagnostic CT scans: assessment of patient, physician and radiologist awareness of radiation dose and possible risk. Radiology 2004;231:393-398), although some institutions are requiring patient informed consent prior to undergoing CT. While it seems like this would deter patients from getting potentially important exams performed, a recent research study found that parents who were told about the risks and benefits of CT still agreed to go ahead and have the study performed (Larson DB, et al. Informing parents about CT radiation exposure in children: it’s OK to tell them. AJR 2007;189:271-275). In short, you should not hesitate to discuss the potential risks of CT radiation with patients and families.

Where can I find guidelines/protocols for pediatric CT?
Return to the “What can I Do?” section of this website for specific suggestions and guidelines for every member of the Imaging team including protocol recommendations.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s