Transcript CT_training - Wake Forest Baptist Health - Winston

CT Scan Site Training
Year 20 Exam
J. Jeffrey Carr, MD, MSCE
April 2005
Wake Forest University School of Medicine
Departments of Radiology &
Public Health Sciences
Objectives
• Learn about the study.
• Learn and understand the CT scanning
protocol.
• Opportunity ask/submit questions to the
CTRC at Wake Forest!!!!
• This presentation is designed to provide the
needed information and supplement the
detailed CT manual of operation which is
located in the 3-ring binder provided to each
CT scan site.
What is CARDIA?
• CARDIA is studying how heart disease starts
in young adults to develop prevention
strategies for heart attacks and strokes.
• Calcified Atherosclerotic Coronary Plaque
(CACp) indicates:
• Subclinical disease
• Higher risk of heart attacks and CVD deaths
• We are doing the Cardiac CT exams so we
can determine how calcified plaque has
changed since the year 15 exam.
CARDIA Year 20 CT exam
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Wake Forest U. Health Sciences - CTRC
How is the study organized?
• 4 field centers across the country
• Birmingham, Chicago, Minnesota, San Francisco
• CT Reading Center
• Wake Forest U. Health Sciences
Winston-Salem, NC
• Data Coordinating Center
• Univ. of Alabama-Birmingham
• Other components: laboratory, ultrasound,
genetics, etc… across the country
CARDIA Year 20 CT exam
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CARDIA Coordinating
Center
CT Reading Center will
send the results to the
data coordinating center
UAB
CT exams will be sent to
WFU using a DICOM
send from the CT site
WFU
CT Reading
Center
UAB CT
UMN CT
Chicago CT
San Francisco
CT
CT exams will be performed
at the 4 Field Centers
~ 3,200 participants
Let’s Learn the CT Protocol!
• Phantom Quality Control (QC)
procedures
• Phantom placement for scanning
• ECG stuff
• CT scanning stuff
• Sending the images to us at Wake
Forest
Scales Require Calibration So do CT Scanners!
QuickTi me™ and a
T IFF (Uncompressed) decompressor
are needed to see thi s pi cture.
•We all know that you can “adjust” the zero value of a scale to
weight “heavy” or preferably “light”
• CT Scanners can have the CT number value of water (0 H.U.)
adjusted to be “brighter” or “darker”
CARDIA Year 20 CT exam
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Wake Forest U. Health Sciences - CTRC
CT Phantom – Parts
Setup for Quality Control scans
Torso phantom (oval)
Center
torso
plug
QCT Calibration phantom
(rectangle)
Other parts
• Blue cushion with insert
for QCT phantom
• Gel bag (goes b/t patient
and phantom)
• Made by Image Analysis
4 tubes containing:
0, 50, 100 & 200 mg/cc Calcium
Why are we scanning the
Torso & QCT phantoms?
• To make sure your CT scanner’s ability to
measure CT numbers (HU) is correct & not
changing over time
• Participant scanning
• Allow adjustment so that scores will be as similar
as possible across sites using different CT
scanners
• Objective measure of “noise” in scan
QC Scan Procedure –
1st & 15th of each month
• Place calibration phantom on CT couch
• Mark position with tape (optional)
• Place torso phantom in middle of calibration
phantom
• Mark position with tape
• Align torso phantom so “center plug” is at
isocenter
• Record table height
• Mark positioning with tape so you can quickly set
it up each time in the same position.
QA Scanner Setup
This should be
at isocenter
using your laser
alignment
system
QA procedure – twice a month
1st & 15th of each month
• Perform scan of Torso & QCT phantom twice every
month
• Use the CARDIA protocol saved in the CT scanner
• Scouts
• Axial scans (cardiac series- ECG gating off or simulated)
• Send images to WFU Reading Center just like a
participants scan
• Measure regions-of-interest (roi’s) on scanner
• 4 along bottom + 1 center plug
• Record on QA sheet in your CARDIA CT notebook
• Fax to Reading Center (fax 336.716.4340)
Example CT System data entry for
QCT Torso Phantom:
Name:
ID number:
QC UAB
UABYYMMDD
CARDIA Year 20 CT exam
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When the phantom is scanned on
April 1st 2005 at UAB:
Name:
ID number:
QC UAB
UAB050401
(or UI050401, UMN050401, WC050401)
CARDIA Year 20 CT exam
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When the phantom is scanned on
April 15th 2005 at UAB:
Name:
ID number:
QC UAB
UAB050415
CARDIA Year 20 CT exam
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Preparing for Participants
•Scan feet or head
first - but be
consistent at your site
•Place QCT phantom
in blue holder
(optional)
•Place gel bag over
plastic QCT phantom
(optional)
•Position participant
so that phantom is
underneath the heart
CT Scan of heart with QCT phantom
QCT
phantom
with 4 tubes
Entering Participant Information
Into the CT Scanner
• We are entrusted to maintain the
confidentiality of the participant for now and
in the future.
• For the results to be meaningful we have to
positively identify each person.
• We will identify participants by codes
assigned by the coordinating center – two
codes are used:
• Study ID number (a.k.a. SID)
• Pseudonym (alpha code)
Example CT System data entry
demographic fields:
Name:
ID number:
Date of Birth:
Weight:
Technologist:
Referring Physician:
Indication:
ABCDE160
12345
03 MAR 1947
160 lbs
51
Marcus Welby
CARDIA y20
CARDIA Year 20 CT exam
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Wake Forest U. Health Sciences - CTRC
How do you know what to type in
to the CT scanner?
• Each participant is consented & screened by
the clinic prior to the CT exam
• Consent form is sign
• Women are check for potential pregnancy
• The participant is scheduled for the CT exam
• You will be sent a Cover Sheet & “CT scan
completion Form 76” (A copy of this form is in
the appendix of the MOO)
CARDIA Year 20 CT exam
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CT scan completion Form 76
Acrostic
to replace
real name
Study ID
DOB &
Gender
Weight
CARDIA Year 20 CT exam
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CT Eligible
CARDIA Year 20 CT exam
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CT scan completion Form 76
CT Tech
ID
Let us
know any
problems!
CARDIA Year 20 CT exam
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Wake Forest U. Health Sciences - CTRC
CT Scanning overview
• Scouts - Thoracic
• Frontal
• Lateral (optional)
• Heart 1 w/ ECG gating
• Heart 2 w/ ECG gating
Participant Preparation
• Instruction prior to scan (tell clinic staff)
• No caffeine products before scan
• Will have to change into gown
• Have clinic fax / deliver participant CT scheduling
and CT completion forms prior to study.
• Immediate pre-scan
• Change into hospital gown or loose clothing
• Easier if opens in front (placing ECG leads)
• Safety checks which are routine at your institution
(i.e. LMP, pregnancy etc..)
Breathholding
• Script =
•
•
•
•
•
“Take a deep breath in <pause>
blow it all the way out <pause>
Take a deep breath in <pause>
blow it all the way out <pause>
Take a deep breath in and hold it.
• ******Scan 20-40 seconds*****
• Breath and relax”
Cardiac CT scan is during
Inspiration
• Greeting participant
• Make sure they are the right person and they are
there for the “CARDIA CT Scan”
• Prepare participant by indicating there will be
several times they are asked to hold their breath
– some short (the scouts) and some longer
• Instruction & observation during scout
images
• Watch how they do – provide further instructions
• Heart scan 1
• Rest period (2 minutes) check 1st study
• Heart scan 2
Breathholding – why so long?
• End inspiration.
•
•
•
•
Pushes liver down.
Valsalva lowers heart rate.
Easier to do than end expiration.
Blowing off C02 (hyperventilation) makes it easier!
• Must do same breathing instructions for scout
and heart scans.
• Consider pre-recorded voice if available.
• Have them do the best they can – breath out
slowly if they cannot hold the entire time.
ECG – Lead placement
• Arms overhead
• Reposition leads if necessary
• Make sure amplitude (i.e. size) is OK per your CT
scanner instructions
ECG positioning
• Manufacturer or local recommendations
• “White is Right –
Smoke (black) over Fire (red) (left side)
• Must have identifiable R-wave for gating
• Reposition leads, check connections
• Prospective triggering/gating mode-late
diastole phase
• EBCT @ 80% (636-736)
• Siemens at 50%-TBD, (428, 755)
• GE at 70% ( 437-763)
Check Thorax Scouts for:
• Participant centered?
• Phantom centered and behind spine?
• Prescribe cardiac scan
• Carina thru inferior aspect of the heart
• Lateral scout may be useful to prescribe AP
centering of reconstructions – be sure to
include the entire QCT phantom in the
35 cm FOV !!!!!!!!
Scouts – QCT Position &
Landmarks for Prescribing Scans
Start
End
Start
End
QCT Phantom
underneath participant
QCT Phantom
underneath participant
CT Technique –
Siemens Sensation 16
• Axial mode “CaScSeq”
• Kernel B30F
• cardiac gating/triggering per CT system
specific protocol (50%)
• KVp 120, 6 slices by 3 mm
• 0.4 sec gantry rotation, partial scan
reconstruction - “Quick Scan”
CARDIA Year 20 CT exam
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CT Technique –
MDCT
Weight determines the mAs for the
cardiac scans !!!!!
The participant is weighed at the clinic
and the weight is printed on CT
completion form 76
CARDIA Year 20 CT exam
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Weight and mAs
If the weight is less than 220 lbs
Set mAs = Standard
If the weight is 220 lbs or greater
Set mAs = Standard*1.25%
CARDIA Year 20 CT exam
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Cardiac Scan 1
•
•
•
•
Check coverage
Check centering
Check ECG
Confirm correct technique (KV, mAs,
slice thickness 3 mm or 2.5 mm)
• Fix anything that is sub optimal
• Go to cardiac scan 2
Check and make adjustments
after the first scan!!!!!!!!!!!
Preparing for Heart2
Why Two Scans of the Heart?
• Best estimate is the average of the both
• If there is a problem with 1 scan - we will use
the information from the other
• If there is a problem with – note in the
comment field on the scan completion form
76
• Don’t do a third scan!!! This will result in
increase radiation exposure to the
participant!!!
Reconstruct Thin slices
• GE MDCT - Retrorecon
• 1.25 mm slice thickness at 26 cm dfov
• 5 mm slice thickness at 50 cm dfov
• Siemens - Recon between
• 1-1.5 mm at 26 cm dfov
• 5 mm slice thickness at 50 cm dfov
• GE Imatron • no thin slice recons
• 5 mm slice at a 50 cm dfov
CARDIA Year 20 CT exam
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Internet Transfer of CT scans
• Scans will be transferred to the CT reading
center over the Internet
• DICOM send from a computer workstation or the
scanner depending upon your networks configurations
• CT center will coordinate with your site
• Contact Josh Tan or Chris O’Rourke
• [email protected]
• [email protected] 336 716 8909
• Main: 336.716.7234
• Send Entire Exam
• Heart 1
• Heart 2
• Additional reconstructions
DICOM Networking to WFU
• Your CT scanner or workstation should already be
configured to send to our Reading Center
• It is recommended that you configure in the protocol
to automatically send to WFU and anywhere else you
want the exam to go.
• Alternatively send it to us as soon as possible
• Fax the Scan Completion form to the CT Reading
Center (fax no. 336-716-4340) and to your local clinic
• Store in Notebook (3 ring binder)
We are here to help you and answer
any questions
• Call us at:
• Let the Reading Center know your
concerns!!!
• We will try very hard to make
adjustment which will make your life
easier and listen to your suggestions
“Homework”
• Copy of CT system’s last full calibration
by field engineer of physicist and send
to us
• Verify reconstruction thickness
• Program “CARDIA Y20” protocol into
CT scanner
CARDIA Year 20 CT exam
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