Image Gently, Step Lightly: Practice of ALARA in Pediatric Interventional Radiology

1
Image Gently, Step Lightly Practice of ALARA
inPediatric Interventional Radiology

• John M Racadio, MD1
• Bairbre Connolly, MB2
• 1 Cincinnati Childrens Hospital Medical Center
• 2 The Hospital for Sick Children, Toronto

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Why is this important?

• 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 1980s.
• 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
35859-866. 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
5331-338. 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 2159-162.
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ALARA

• 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

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Learning objectives

• 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.

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Practical Tips to Reduce Radiation Dose to
Patients and IR Staff
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Guiding Principles

• Approach Radiation protection
• 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.

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Guiding Principle

• 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.
• To optimize radiation for the patient and
  minimize radiation for staff

GOAL
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Unique Features of Pediatric Intervention

• Pediatric size (500gm 100Kg)
• Proximity of operator to the beam
• Trade off Need access to child
  but 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

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In Practice

• How many times have we
• 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?

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Proper Radiological Positioning

• 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!

Rad Techs play crucial role
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Control Fluoroscopy

• 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
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Reduce Dose

• Reduce field size (collimate)
• Minimize field overlap.
• Use low pulsed fluoroscopy
• (7 or 3/sec)
• Use low frame rate (4 or 2 or
  1/sec)
• Avoid unnecessary runs

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Personal Protection - Hands

• Keep hands out of the beam
• Finger /ring badges
• Angle of beam off hands
• Collimation
• Care

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Control Images

• Limit acquisition to what is essential for
  diagnostic and documentation purposes.
• Last image hold
• Think - Plan each run
• Think - frames / second
• Think - magnification

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Personal Protection - Shields

• Lead table skirt / drape
• Over head shields
• Mobile Devices
• Radioprotective non-lead
  
  
• patient drapes
  
  

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Personal Protection Awareness of Geometry

• 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

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Personal Protection - Wear

• Well fitted lead apron (knees)
• Leaded glasses (with sides)
• Thyroid shield
• Lead gloves anesthetist -
  operator

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Team Ergonomics

• 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

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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
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Potential Strategies to Optimize Radiation
Exposure from Interventional Fluoroscopy
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Ideal World

• Clinical Success
• The Least Amount of Radiation
• Adequate Image Guidance
• Established Practice Guidelines
• Based on scientifically well designed studies.

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Todays Reality

• Many IR procedures require high quality images,
  long fluoroscopy time or both.
• There are NO consensus guidelines.
• Practices vary from institution to institution,
  and even within an institution.

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Where Can We Start?

• Optimize operating parameters for x-ray machines.
• Regularly inspect and maintain equipment.
• Adequately train staff on equipment capabilities
  re image quality and dose.
• Develop QA and QC Dosimetry Programs

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Equipment

• Include Medical Physicist in decisions.
• Machine Selection and Maintenance
• Incorporate Dose-Reduction Technologies and
  Dose-Measurement Devices in equipment.
• Establish Facility Quality Improvement Program
• Appropriate x-ray equipment QA program
• Overseen by a medical physicist
• Equipment evaluation/inspection

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Education and Training

• Comprehensive Training of Operators
• Radiation Biology, Physics, and Safety
• Attend high-quality courses or complete a
  self-training course given by appropriate
  professional societies.
• Comply with applicable state requirements.

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Dosimetry Records

• Measure and Record Patient Radiation Dose
• Record Fluoroscopy Time
• Record Available Measures
• 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.

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Dosimetry Follow-UP

• Develop Methods to Quantify Late Effects
• Design medical records to clearly document the
  number and types of interventional procedures
  received by the patient.
• Maintain a database of all patients with
  procedures and dose information.
• Review dose information to identify patients with
  high doses (gt3Gy) for follow-up.
• Establish procedures for follow-up including
  skin examination at 30 days.

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Dosimetry Follow-UP

• CCHMC Policy
• Machine specific action level
• for patient call back based on
• 3 Gy (300 rad) entrance skin dose.

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Physician-Patient Interactionpre-procedure

• Ask patient about prior history of interventional
  fluoroscopy.
• Communicate details of the procedure, patient
  dose, and immediate and long-term health effects
  to patients and their primary care providers.
• Counsel patients on radiation-related risks, as
  appropriate, along with the other risks and
  benefits associated with the procedure.

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Physician-Patient Interactionpost-procedure

• Schedule a 30 day Follow-Up Visit if
• Radiation Skin Dose /gt 2 Gy, or
• Cumulative Dose /gt 3 Gy
• Send interventional fluoroscopy procedure
  description, operative notes, doses and
  information about the possible short-term and
  long term effects to the patients primary care
  provider.
• The patient and primary care physician should be
  specifically requested to notify the operator if
  observable skin effects occur.

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Monitor and ImproveOperator Performance

• Audit outcomes of procedures (including patient
  radiation dose for each operator).
• Share information learned in audits with
  operators and provide additional training as
  needed.
• Provide annual radiation safety education for all
  operators.
• Collaborate in clinical trials to identify best
  practices for optimizing doses to patients and
  minimizing dose to health care providers.

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Technologic Advances Impact on IR Dosimetry
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Technologic Advances

• 3D Rotational Angiography
• Flat Detector Systems
• Cone Beam CT (CT-Like Imaging)

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3D Rotational Angiography
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Cone Beam CT (CT-Like Imaging)
These are NOT images from a CT. These are from
IR flat detector c-arm
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3D CT Guidance
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Our Collective Responsibility

• More dosimetry studies in modern Pediatric IR
  suites need to be performed.
• Manufacturers need to be made aware of the
  importance of limiting radiation exposure to
  children.
• New technologies should be embraced, but
  dosimetry evaluation must be a priority.

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