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Image Gently, Step Lightly:
Practice of ALARA in
Pediatric Interventional Radiology
John M Racadio, MD1
Bairbre Connolly, MB2
1
Cincinnati Children’s Hospital Medical Center
2 The Hospital for Sick Children, Toronto
Why is this important?
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In March, 2009, the National Council on Radiation Protection and
Measurement released a critical report that indicated that
radiation dose to the United States population had risen
dramatically since the early 1980’s.
IR procedures are the third largest contributor to medical
radiation to the US public.
Children are more sensitive to radiation effects and have a longer
life span during which manifest possible changes as a result of
radiation exposure.
Children who undergo interventional procedures may have a
chronic illness and receive a higher lifetime cumulative dose
secondary to repeat procedures and exposure.
Kase KR (2009) Ionizing Radiation Exposure of the Population of the United States. National Council on Radiation
Protection and Measurements, Bethesda, Maryland.
Swoboda N, Armstrong D, Smith J, et al. (2005) Pediatric patient surface doses in neuroangiography. Pediatr
Radiol 35:859-866.
Rose S, Andre M, Roberts A, et al. (2001) Integral role of interventional radiology in the development of a
pediatric liver transplantation program. Pediatr Transplant 5:331-338.
Ahmed B, Shroff P, Connolly B, et al. (2008) Estimation of Cumulative Effective Doses From Diagnostic and
Interventional Radiological Procedures in Pediatric Oncology Patients. Society for Pediatric Radiology,
Scottsdale, Arizona.
Thierry-Chef I, Simon S, Miller D (2006) Radiation dose and cancer risk among pediatric patients undergoing
interventional neuroradiology procedures. Pediatr Radiol 36 Suppl 2:159-162.
ALARA
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“As low as reasonably achievable”
General principle guiding radiation exposure
Keep radiation dose exposure to patient as
low as reasonable for each procedure, given
clinical need and patient factors
Learning objectives
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Be familiar with practical strategies that are
useful to reduce dose to patients & staff
undergoing image guided procedures.
Learn about possible QA options to consider
implementing in our own suites to improve our
practice of radiation protection
Briefly describe some recent technologic
advances and their impact on IR Dosimetry.
Practical Tips to Reduce Radiation
Dose to Patients and IR Staff
Guiding Principles
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Approach Radiation protection
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patient and staff
Patient: Radiation dose is optimized when
imaging is performed with the least amount of
radiation required to provide adequate image
quality and image guidance.
Guiding Principle
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Staff: Scattered radiation in the room is
directly proportional to the patient dose; if
patient dose is reduced, so too is the dose to
the operator and team.
GOAL
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To optimize radiation for the patient and
minimize radiation for staff
Unique Features of
Pediatric Intervention
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Pediatric size (500gm – 100Kg)
Proximity of operator to the beam
Trade off: Need access to child
want hands out of the beam
Size of the I.I. relative to the child
Need for magnification ( dose)
Pediatric patient more radiation sensitive
Pediatric longevity
Use US where possible
but
In Practice
How many times have we:
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left our hands in the beam?
expediency over personal safety?
our backs to the X-ray source?
unaware of our foot on the pedal?
pushed away a protective barrier?
Proper Radiological Positioning*
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Maximize distance between x-ray tube & patient.
Minimize distance between patient & Image Intensifier.
Stand on side of the Image Intensifier
Inverse square law – make use of it!
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* Rad Techs play crucial role
Control Fluoroscopy
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Collimate
Limit use to necessary evaluation of moving
structures.
Employ last-image-hold to review findings
Unnecessary/Inadvertent fluoro – Make Aware!
Time bell warning
Reduce fluoroscopy pulses/sec to as low as
possible/suitable (30/sec, 15/sec, 7.5/sec, 3.5/sec)
System in the room – increases dose awareness
IG Checklist
ALARM
PEMNET
Reduce Dose
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Reduce field size (collimate)
Minimize field overlap.
Use low pulsed fluoroscopy
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(7 or 3/sec)
Use low frame rate
(4 or 2 or 1/sec)
Avoid unnecessary runs
Personal Protection - Hands
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Keep hands out of the beam
Finger /ring badges
Angle of beam off hands
Collimation
Care
Control Images
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Limit acquisition to what is essential for
diagnostic and documentation purposes.
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Last image hold
Think - Plan each run
Think - # frames / second
Think - magnification
Personal Protection - Shields
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Lead table skirt / drape
Over head shields
Mobile Devices
Radioprotective non-lead
patient drapes
Personal Protection –
Awareness of Geometry
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Maintain awareness of body position relative to
the x-ray beam
Horizontal x-ray beam: operator and staff should
stand on the side of the image receptor (I.I.)
Vertical x-ray beam: the image receptor should be
above the table.
Angle beam where possible
I.I.
I.I.
Personal Protection - Wear
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Well fitted lead apron (knees)
Leaded glasses (with sides)
Thyroid shield
Lead gloves – anesthetist
- operator
Team Ergonomics*
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Train operators and staff in ergonomics of the
room - good positioning when using fluoroscopy
equipment; periodically assess their practice.
Inverse Square Law
Front or Back lead
Identify and provide the best personal protective
gear for operators and staff.
•Acknowledge expertise & vigilance
of our technologists
Summary
Goal
To optimize radiation for the patient
and minimize radiation for staff
1. AWARE
2. ALARA - Steps to reduce patient dose
3. ALERT - Steps to minimize staff dose
Potential Strategies to
Optimize Radiation Exposure from
Interventional Fluoroscopy
Ideal World
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Clinical Success
The Least Amount of Radiation
Adequate Image Guidance
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Established Practice Guidelines
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Based on scientifically well designed studies.
Today’s Reality
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Many IR procedures require high quality
images, long fluoroscopy time or both.
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There are NO consensus guidelines.
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Practices vary from institution to institution,
and even within an institution.
Where Can We Start?
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Optimize operating parameters for x-ray
machines.
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Regularly inspect and maintain equipment.
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Adequately train staff on equipment
capabilities re: image quality and dose.
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Develop QA and QC Dosimetry Programs
Equipment
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Include Medical Physicist in decisions.
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Machine Selection and Maintenance
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Incorporate Dose-Reduction Technologies and Dose-Measurement
Devices in equipment.
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Establish Facility Quality Improvement Program
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Appropriate x-ray equipment QA program
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Overseen by a medical physicist
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Equipment evaluation/inspection
Education and Training
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Comprehensive Training of Operators
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Radiation Biology, Physics, and Safety
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Attend high-quality courses or complete a selftraining course given by appropriate
professional societies.
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Comply with applicable state requirements.
Dosimetry Records
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Measure and Record Patient Radiation Dose
Record Fluoroscopy Time
Record Available Measures
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DAP (Dose Area Product)
Cumulative Dose
Skin Dose
Inform patients who have received high doses to
examine x-ray beam entrance site for skin erythema.
Dosimetry Follow-UP
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Develop Methods to Quantify Late Effects
 Design medical records to clearly document the number and
types of interventional procedures received by the patient.
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Maintain a database of all patients with procedures and dose
information.
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Review dose information to identify patients with high doses
(>3Gy) for follow-up.
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Establish procedures for follow-up; including skin examination at
30 days.
Dosimetry Follow-UP
CCHMC Policy:
Machine – specific
action level
for patient call back
based on
3 Gy (300 rad)
entrance skin
dose.
Physician-Patient Interaction
pre-procedure
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Ask patient about prior history of interventional
fluoroscopy.
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Communicate details of the procedure, patient dose,
and immediate and long-term health effects to
patients and their primary care providers.
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Counsel patients on radiation-related risks, as
appropriate, along with the other risks and benefits
associated with the procedure.
Physician-Patient Interaction
post-procedure
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Schedule a 30 day Follow-Up Visit if:
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Radiation Skin Dose =/> 2 Gy, or
Cumulative Dose =/> 3 Gy
Send interventional fluoroscopy procedure
description, operative notes, doses and information
about the possible short-term and long term effects
to the patient’s primary care provider.
The patient and primary care physician should be
specifically requested to notify the operator if
observable skin effects occur.
Monitor and Improve
Operator Performance
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Audit outcomes of procedures (including patient
radiation dose for each operator).
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Share information learned in audits with operators
and provide additional training as needed.
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Provide annual radiation safety education for all
operators.
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Collaborate in clinical trials to identify best practices
for optimizing doses to patients and minimizing dose
to health care providers.
Technologic Advances:
Impact on IR Dosimetry
Technologic Advances
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3D Rotational Angiography
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Flat Detector Systems
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Cone Beam CT (“CT-Like Imaging”)
3D Rotational Angiography
Cone Beam CT (“CT-Like Imaging”)
These are NOT images from a CT. These are from IR flat detector c-arm
3D “CT” Guidance
Our Collective Responsibility
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More dosimetry studies in modern Pediatric
IR suites need to be performed.
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Manufacturers need to be made aware of the
importance of limiting radiation exposure to
children.
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New technologies should be embraced, but
dosimetry evaluation must be a priority.
References
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