Transcript Image Gently Back to Basics Digital Radiography campaign overview

“Back to Basics”
Campaign in Digital Radiography
Sponsored by the Alliance for Radiation
Safety in Pediatric Imaging
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The Alliance for
Radiation Safety in
Pediatric Imaging
The image gently campaign
Copyright 2012 Alliance for Radiation Safety in
Pediatric Imaging All Rights Reserved
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What is Image Gently
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An education, awareness and advocacy campaign
To improve radiation protection for children worldwide
Alliance for Radiation Safety in Pediatric Imaging
>70 health care organizations/agencies
>800,000 radiologists
radiology technologists
medical physicists worldwide
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The Alliance for Radiation
Safety in Pediatric Imaging
The Image Gently Alliance
is a coalition of health care organizations dedicated to
providing safe, high quality pediatric imaging worldwide.
The primary objective of the Alliance is to raise
awareness in the imaging community of the need to
adjust radiation dose when imaging children.
The ultimate goal of the Alliance is to change practice.
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Introduction
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Pediatric patients are unique
Children are much more sensitive to radiation induced
cancer than adults
Younger children are more sensitive
Girls more sensitive than boys (breast, thyroid)
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Exposure to the Public
1987 Exposure
2006 Exposure
2% 0.3%
2% 0.1%
Background
15%
Medical X-rays
Consumer
Products
Ocupational
83%
1987
2006
Collective effective dose
(person-Sv)
835,000
1,870,000
Effective dose per
individual in U.S.
3.6
6.2
http://www.ncrponline.org/PDFs/Poster.pdf
50%
48%
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What is ALARA?
As Low as Reasonably Achievable
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Don’t do exams that are not indicated
Utilize imaging without ionizing radiation when possible
When doing exam using radiation, tailor to clinical
question and size of child
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Some facts
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A single Gray (Gy) is a large dose of radiation
Most medical doses are milliGray (mGy)
Sieverts are a similar measure but uses a weighting
factor for type of radiation and tissue affected. It is
used in risk estimates.
For practical purposes 1mGy = 1mSv for a whole body
exposure
Background radiation is about 3 mSv/year
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www.imagegently.org
Relative radiation dose
Modality
CT
Interventional
Fluoroscopy
Nuclear medicine
Radiographs
Ultrasound, MR
Background Equivalent
 8 months +
 1 month - 6 months
 10 days +
 1 day +
 1 day background +
 None
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Two types of radiation effects
High dose
Lower dose
deterministic effects (acute)
stochastic effects (delayed)
http://www.imagewisely.org/~/media/ImageWisely%20Files/Medical%20Physicist%20Articles/IW%20Peck%20Samei%20
Radiation%20Risk.pdf?CSRT=2333474185835724304
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Deterministic effect: Dose dependent
with threshold
predictable
New York Times July 31, 2010
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Stochastic effect
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Potential for cancer
Potential for genetic effects
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Risk of event occurring is dependent on dose
There is assumed to be “no threshold”
From: Slovis T, Frush DP
Medical Radiation and Children
Powerpoint, www.pedrad.org. 2007
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Theoretical relative risk is very, very
low if it exists at all….
Activity
Death (per million/year)
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Radiation Safety in Pediatric
Imaging All Rights Reserved
Having a chest x-ray
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https://www.cchs.net/onlinelearning/content/pedrad/topics/radiation/radiation.HTM
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Does medical radiation cause cancer?
We don’t know
We should act cautiously
as if there is a potential risk
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Recent AAPM statement
The American Association of Physicists in Medicine (AAPM) acknowledges that medical
imaging procedures should be appropriate and conducted at the lowest radiation dose
consistent with acquisition of the desired information. Discussion of risks related to radiation
dose from medical imaging procedures should be accompanied by acknowledgement of
the benefits of the procedures. Risks of medical imaging at effective doses below 50
mSv for single procedures or 100 mSv for multiple procedures over short time periods
are too low to be detectable and may be nonexistent. Predictions of hypothetical cancer
incidence and deaths in patient populations exposed to such low doses are highly speculative
and should be discouraged. These predictions are harmful because they lead to
sensationalistic articles in the public media that cause some patients and parents to refuse
medical imaging procedures, placing them at substantial risk by not receiving the clinical
benefits of the prescribed procedures.
AAPM members continually strive to improve medical imaging by lowering radiation levels and
maximizing benefits of imaging procedures involving ionizing radiation.
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Appropriate Approach
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Measure part thickness
Only include necessary
anatomy
Select appropriate
technique
No grids used for parts less
than 10-12 cm in thickness
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Use collimation to
decrease patient exposure
Automatic exposure
control (AEC) lowers dose
and standardizes dose but
may not be an option for
smaller children
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How to optimize digital radiography
for pediatric patients… back to basics
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Measure part thickness
Use a technique chart for consistency
Update your technique chart to provide
accurate exposures
Check your anatomical programming for
accuracy
Use AEC on larger patients for consistent
images at lower doses
Calipers for body part
thickness measurement
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What are grids?
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Grids are devices that selectively allow
primary x-rays to be transmitted and
scattered x-rays to be absorbed in the
grid
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Subsequently, grids can improve
image contrast
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When should grids be used ?
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While grids improve film
quality for large patients,
they ADD to patient dose
Used on parts where
greater thickness will
produce scatter
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Use a grid for body parts
over 10-12 cm in
thickness
VERY few instances
where grids should be
uses for younger, smaller
children
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Digital Radiography is different than
Film/Screen Radiography
A different approach must be used !
With digital radiography there is an uncoupling effect
Screen-Film
 Direct relationship
between exposure
and image
Digital imaging (CR/DR)
 Computer processing
adjust image for
acceptable grayscale
regardless of exposure
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Uncoupling Effect
Screen-Film Radiography: Too high a dose = black film
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Film screen
A. Underexposure
B. Optimal
C. Overexposure
Seibert, J. A. and R. L. Morin (2011). Pediatr
Radiol 41(5): 573-581. Reprinted with permission.
Digital imaging (CR/DR): Too high a dose = equipment compensates;
film appears to be properly exposed
A. Underexposure
B. Optimal
C. Overexposure
Seibert, J. A. and R. L. Morin (2011). Pediatr
Radiol 41(5): 573-581. Reprinted with permission.
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Pediatric Imaging All Rights Reserved
Exposure Indicators
What are they?
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What do they mean?
Primary tool to ensure
that accurate exposure
factors are utilized in
x-ray production in
digital radiography
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It indicates the efficiency
and sensitivity of the
digital receptor to incident
x-rays and, ideally,
provides feedback to the
technologist regarding the
proper radiographic
exposure for a specific
exam
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Proprietary Exposure Indicators
Proprietary Exposure Indicators and Vendor Recommendations
Fuji
AGFA
Kodak
Detector Exposure
Estimate (mR)
> 1000
<1.45
<1250
<0.20
601-1000
1.45-1.74
1250-1549
0.2-0.3
301-600
1.75-2.04
1550-1849
0.3-0.7
150-300
2.05-2.35
1850-2150
0.7-1.3
75-149
2.36-2.65
2151-2450
1.3-2.7
50-74
2.66-2.95
2451-2750
2.7-4.0
<50
>2.95
>2750
>4.0
Action
Underexposed: Repeat
Underexposed: QC exception
Underexposed: QC review
Acceptable Range
Overexposed: QC review
Overexposed: QC exception
Overexposed: Repeat if necessary
Williams MB, Krupinski EA, Strauss KJ, et al. J Am Coll Radiol. 2007;4(6):371-388. Reprinted with permission.
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New Exposure Index
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The IEC (62494-1) has
created a unified
international standard
Eliminates confusing
proprietary terms
Makes establishing
national databases easier
due to commonality
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Can be applied to all
future digital
radiography equipment
Not currently required
by any government
regulations
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Patient Dose
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Measurement is difficult
Many factors influence patient dose
 Beam quality – kVp & filtration
 Entrance skin exposure (ESE)
 Distance of patient from source
 Body part/organs exposed – depth, overlaying
structures
 The area of the entrance beam
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ACR Dose Registry
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National Radiology Data Registry (NRDR)
The ACR is establishing a Digital Radiography
This is an important step in developing national
exposure reference levels for pediatric examinations
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Use of DAP
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Dose Area Product
Reflects amount of radiation and the size of the x-ray
field
Expressed in Gray centimeters squared (Gy*cm2)
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Reasons for Repeated Exam
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Artifacts
Mispositioning
Over-collimation
Patient motion
Double exposure
Inadequate inspiration
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Overexposed - high
exposure index
Underexposed - low
exposure index
Marker missing or wrong
Wrong exam
Wrong patient
Lost image
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Reasons for Repeated Exams:
Errors Unique to Digital
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Utilization of image
cropping in place of
collimation
Overexposure utilized to
prevent repeat
Misunderstanding of
exposure indicators
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Inappropriate image
processing due to
histogram analysis
error
Detector Lag
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What do we need to do?
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RT’s, radiologists, medical physicists, and
manufacturers must work to balance exposure and
image quality to achieve ALARA
Purchase equipment that uses the IEC standard
Develop and utilize educational materials
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BACK TO BASICS
Image Evaluation Tool
Beam
 Artifacts
 Shielding
 Immobilization and Indicators
 Collimation
 Structures
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Beam
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Is the anatomy in the center of the image?
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Central ray
Tube angle
Device alignment
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Artifacts
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Is there anything obstructing that requires a
repeat?
L
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Shielding
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Was gonadal protection utilized
appropriately?
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Immobilization
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Can the baby, toddler, or child follow
instructions?
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Indicators
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Is the exposure indicator in appropriate
range?
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Is deviation index ideal?
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Collimation
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Is collimation appropriate?
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Reliance on electronic cropping after
exposure is not an acceptable practice
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Examples
COLIMATE TO AREA
OF INTEREST
BEFORE EXPOSURE
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Examples
COLIMATE TO AREA
OF INTEREST
BEFORE EXPOSURE
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Examples
COLIMATE TO AREA
OF INTEREST
BEFORE EXPOSURE
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Examples
COLIMATE TO AREA
OF INTEREST
BEFORE EXPOSURE
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What’s happens if you crop after,
instead of collimate before
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There may be legal ramifications if the entire
exposed area is not utilized for diagnosis
Image processing errors may occur
Unnecessary areas of patient tissue are irradiated
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Structures
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Is necessary anatomy or device properly
demonstrated?
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imagegently.org
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Pediatric Imaging All Rights Reserved
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