IMAGE GENTLY AND NEW JERSEY CT DOSE PROJECT UPDATE

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IMAGE GENTLY ANDNEW JERSEY CT DOSE PROJECT
UPDATE

• New Jersey Medical Physicist
• Meeting
• March 6, 2008

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Image Gently Campaign

• Launched by The Alliance for Radiation Safety in
  Pediatric Imaging on January 22, 2008
• Formed in 2007
• Made up of 13 Healthcare Organizations

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Who is the Alliance?

• American Association of Physicists in Medicine
• American College of Radiology
• American Society of Radiologic Technologists
• The Society for Pediatric Radiology
• American Academy of Pediatrics
• American Osteopathic College of Radiology
• American Registry of Radiologic Technologists
• American Roentgen Ray Society
• Association of University Radiologists
• Conference of Radiation Control Program Directors
• National Council on Radiation Protection
• Radiological Society of North America
• Society of Computed Body Tomography and Magnetic
  Resonance
• Founding member

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What is Image Gently Goal?

• Goal Is to change the practice
• To raise awareness of the opportunities to lower
  radiation dose in the imaging of children
• Focus Pediatric CT Procedures
• Key Points
• One Size Does Not Fit All
• Child Size mAs and kVp
• Radiation Matters! What we do now, lasts their
  lifetime
• More is not better
• When we Image, lets Image Gently

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How Can Practice be Changed?

• Answer EDUCATION
• Web (www.imagegently.org) contains educational
  sites for
• Parents
• Physicians
• Medical Physicists
• Technologists
• The Press

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Parents

• Be your Childs Advocate
• Ask Questions regarding
• The use of alternative imaging modalities
• Benefit and Risk and Ways to Reduce Dose
• Ask Questions about the CT Facility
• Is the facility ACR Accredited?
• Are technologists credentialed?
• Are interpreting physicians board certified
  radiologists or pediatric radiologists?

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Physicians, Physicists and TechnologistsHow to
Change your Practice

• Increasing your awareness for the need to
  decrease radiation dose to Children.
• Be committed to make change and work as a team
  with parents, physicians, physicists and
  technologists to decrease dose. Take the web
  Pledge.

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• Know your practice standards
• Use ACRs Appropriateness Criteria for ordering
  procedures.
• Establish CT Protocols for both adult and
  pediatric procedures.
• For Pediatric Protocols
• Child-size mAs and kVp
• Limit scan to only the indicated area
• A single scan is usually adequate (Pre, post and
  delayed contrast scans ( i.e., contrast-enhanced
  multi-phase scanning) rarely add additional
  information.)

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Pediatric CT Protocol Procedure and Excel
Worksheet

• SUMMARY OF INSTRUCTIONS TO ESTABLISH SUGGESTED
  PROTOCOLS
• Establish Adult Protocols for Abdomen and Head
  where the CTDI(vol) are below ACRs reference
  levels of 25 mGy for Abdomen and 75 mGy for Head.
• There are 2 worksheets
• Pediatric Abdomen and Thorax
• Pediatric Head

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• The Abdomen - Thorax worksheet has
• 5 pediatric ages and Average PA Thicknesses
  and 3 adult size Average Thicknesses
• The Med Adult 25 cm is the Adult Protocols
  mAs
• For all other a mAs Reduction Factor (RF) is
  listed.
• The RF for 5yrs of age (14 cm) is 0.59
• The Head worksheet has
• 3 pediatric ages and Average PA Thicknesses and
  1 Med Adult size.
• Enter the mAs used for the Adult protocol in the
  Med Adult as the Baseline .
• Using the Baseline mAs and the mAs Reduction
  Factors, the estimated mAs for each size is
  calculated.

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Abdomen -Thorax Worksheet
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Head Worksheet
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Abdomen Thorax Worksheet Completed Example
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Worksheet/Procedure Limitations

• Worksheet may not work for all CT types
• Worksheet cannot be used if kVp is changed
• In 2006, the AAPM was discussing the issue of
  decreasing kVp from 120 to 80 for pediatric CT
  procedures to improve image contrast. AAPM
  Report 96 supports a lower kVp but no
  suggestions were made.
• Procedure does not discuss the importance of
  Pitch on dose reduction.

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Limitations

• Greater emphasis should have been placed on the
  use of mA Modulation, if equipped.
• AAPM Report 96 reports that the typical
  reduction in mAs from the adult abdomen to an
  infant is 4 to 5 times (Image Gentlys reduction
  factor is 0.43 to 0.51).

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Why is Monitoring CT Dose Important?

• NCRP SC-6-2 Medical Subgroup reported its
  preliminary results in April 2007
• 67 million CT procedures are performed in the
  United States annually. 7 million are pediatric.
  33 of which are performed on children under the
  age of 10.
• In 1993, 18.3 million CT procedures were
  performed. The annual growth of CT procedures
  increased gt10/yr, whereas the U.S. population
  increased by lt 1/yr.
• 73 of CT abdomen and pelvis procedures are
  performed on patients between the ages of 45 and
  84 which account for only 34 of the U.S.
  population.
• CT procedures account for 16 of all medical
  rad/fluoro procedures performed, but contribute
  63 of the dose delivered to patients.

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• Studies conducted by Duke University and The
  University of North Carolina at Chapel Hill on
  the use of CT in ERs reveal significant increase
  use of CT
• From 2000 to 2005 in adult patients. (Some
  stats Head 51, C-Spine 463, Chest 226,
  Abdomen 72) and
• From 2000 to 2006 in pediatric patients (Some
  stats Head 66, C-Spine 731, Chest 675,
  Abdomen 104)
• In the 11th Edition of the Report of
  Carcinogens (2005) published by the USDHHS,
  x-ray and gamma are listed as Known Human
  Carcinogens (first time recognized)
• According to a study published in JAMA Vol. 298
  No.3 on July 18, 2007, the estimated lifetime
  cancer risk from a CT Coronary Angiography (CTCA)
  is between 1 in 143 to 1 in 3261 depending on the
  patients age and gender.

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• According to the BEIR VII Report, the estimated
  lifetime cancer (i.e., solid and leukemia) risk
  from a 100 mSv dose is approximately 1
  individual in 100 persons.
• According to the ACR, Many CT scans have an
  effective dose estimates in the range of 15-25
  mSv for a single study.

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Typical CT Non-CT Effective Doses (Source
AAPM Report 96)
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NJ CT DOSE PROJECT

• History and Second Data Set

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New Jersey CT Dose History

• In 2003-2004, a mail in survey conducted by the
  Bureau of NJ CT facilities revealed a need to
  standardize the method of calculating and
  reporting CT doses.
• Since measuring CT dose is a required test to be
  performed by medical physicists as part of NJs
  Annual CT QC survey, in November 2004, Bureau
  met with NJ medical physicists regarding this
  issue.

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2004 Meeting OutcomesPhysicists Agreed with the
BRH

• A standardized method for calculating and
  reporting CT dose should be used.
• ACRs CT Accreditation Programs method and set
  up procedures for calculating CT dose should be
  used.
• BRH to develop a form to report CT dose.
• CT dose should be calculated and reported for
  Adult Head, Adult Abdomen and Pediatric Abdomen.
• Patient scan protocols should be used.

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2004 Meeting Outcomes

• NJ should apply ACRs CTDI(w) reference levels as
  its reference levels for CTDI(vol).
• This will account for pitch from helical scanning

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Current NJ Reference Levels
Same Reference Levels established by the ACR BUT
NJ uses CTDI (vol) and not CTDI(w)
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March 2006 New Jersey Medical Physicists Meeting

• The Bureau met with medical physicists to review
  CT doses collected from December 2004 to February
  2006.
• This Data Set included 396 CT doses were
  collected on 141 CT scanners. (About 40 of all
  registered CT scanners)
• The following Baseline was established

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Baseline CTDI(vol) Doses (mGy)Data is Established
The 80th percentile is recommended by the AAPM
(May 2005)
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2006 Meeting Outcomes

• For all three procedures, NJs Baseline mean
  CTDI(vol) doses were below ACRs CTDI(w)
  reference levels.
• Facilities experiencing difficulties staying
  below ACRs reference level for Adult Head.
• New Jerseys CT Dose Report updated to provide
  better statistical analysis.
• Education is needed in Multi-Slice CT and
  pediatric abdomen protocols.

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Analysis of Data Set 2 CT Dose Data

• Demographic Information
• Data Set 2 includes CT doses collected from March
  2006 to August 2007.
• A total of 334 CT Doses were collected on 115 CT
  scanners. (About 34 of all registered CT
  scanners)
• Compared to the Baseline, this Data Set consists
  of 62 fewer doses on 26 fewer units.

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Data Set 2 Percentage of Scanners by Slice Type
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Comparison of Slice Type Data
Baseline
Data Set 2
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Significant Changes
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Data Set 2 Percentage of Scanners by Type
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Comparison of Adult Head Dose (mGy)
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Comparison of Adult Head Mean CTDI(vol) Doses
Only 1 dose collected for 6 and 32 Slice Units
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Comparison of Adult Abdomen Dose (mGy)
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Comparison of Adult Abdomen Mean CTDI(vol) Doses
Only 1 dose collected for 6 and 32 Slice Units
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Comparison of Pediatric Abdomen Dose (mGy)
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Comparison of Pediatric Abdomen Mean CTDI(vol)
Doses
Only 1 dose collected for 6 and 32 Slice Units
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Comparison of CT Doses Above NJs CTDI(vol)
Reference Levels (in )
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Analysis of the 19 (22) High Adult Head Doses by
Slice Type
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Analysis of the 3.5 (4) High Adult Abdomen Doses
by Slice Type
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Analysis of the 2 (2) High Pediatric Abdomen
Doses by Slice Type
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Analysis of All (28) High CTDI(vol) by Slice Type
for All Procedures
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NJ Mean mAs Reduction From Adult Abdomen
Image Gently suggests a reduction factor of 0.59
from the average (25 cm) adult to a 5 yrs old (14
cm) child. Note Comparison cannot be made if
kVp is different.
For all slice types, the actual Pediatric mAs
used was lower than the Adult . When kVp was the
same, the actual mAs used for pediatric
procedures were either equal to or lower than the
calculated estimated mAs. (See Slice s 6, 8, 32
and 64). The lower kVp in 2 slice CT units,
resulted in a higher actual mAs used than the
calculated estimated mAs.
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ACRs New Dose RLs and Limits

• Effective January 1, 2008
• CTDI(vol) will be used to determine Dose
  compliance.
• Establishes Dose Reference Levels and Pass/Fail
  Limits.
• Major Dose Limit Changes
• Adult Head increased from 60 mGy to 80 mGy
• Adult Abdomen decreased from 35 mGy to 30 mGy
• Using Data Set 2, these new values will have the
  following effects

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Data Set 2 Adult Head Doses Above ACRs Values
Note Old is prior to 1/1/08 Based on 115
collected doses
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Data Set 2 Adult Abdomen Doses Above ACRs Values
Note Old is prior to 1/1/08 Based on 115
collected doses
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Data Set 2 Pediatric Abdomen Doses Above ACRs
Values
Note Old is prior to 1/1/08 Based on 104
collected doses
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Data Set 2 Observations

• 16 and greater slice scanners may make up the
  majority of registered scanners in NJ.
• As compared to the Baseline, the mean CTDI (vol)
  dose decreased in adult and ped. abdomen and the
  80th tile doses decreased for all procedures.
  Most significant decrease was in Pediatric
  Abdomen which decreased by 20.
• The mean dose increase in Adult Head may be
  contributed to the anticipated increase in ACRs
  limit to 80 mGy.

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Observations (Cont)

• The percent of doses above NJs Reference Levels
  have decreased. Especially, in Adult and
  Pediatric Abdomen.
• Continued education is needed in Multi-Slice CT,
  pediatric protocols and the use of Pitch
• ACRs new dose limits for Adult Head remedies
  Bureaus consider regarding the Reference Level
  being set to low.

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Observations (Cont)

• With the increase in ACRs Adult Head dose limit,
  CTDI(vol) dose may increase. ALARA needs to be
  practiced.
• ACRs new dose limits should not have a negative
  impact on NJ facilities.

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Greater use of a Pitch gt1 is needed
Is there a reason for Pitch to be lt1 for these
procedures? At what point would a Pitch gt1 result
in unacceptable image quality?
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Your Input is Needed

• Image Gently equates a 5 year old child to 14 cm
  PA thickness. Currently, NJ equates to 40 lbs.
  Should we change?
• More effective method of collecting CT Doses
• The 17 month collection period, resulted in data
  from only 34 of registered units. Nearly all
  were collected by Bureau inspectors. Can medical
  physicists send Dose Reports directly to the
  Bureau?
• Except for 3D Reconstruction, is there any reason
  for Pitch to be less than 1?

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Based on ACRs New CTDI(vol) changes, what
should be NJs Reference Levels?
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THANK YOU

• ANY QUESTIONS