CT Scan Site Training Year 20 Exam

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CT Scan Site TrainingYear 20 Exam

• J. Jeffrey Carr, MD, MSCE
• April 2005
• Wake Forest University School of Medicine
• Departments of Radiology
• Public Health Sciences

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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.

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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.

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How is the study organized?

• 4 field centers across the country
• Birmingham, Chicago, Minnesota, San Francisco
• CT Reading Center
• Wake Forest U. Health SciencesWinston-Salem, NC
• Data Coordinating Center
• Univ. of Alabama-Birmingham
• Other components laboratory, ultrasound,
  genetics, etc across the country

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CT Reading Center will send the results to the
data coordinating center
CARDIA Coordinating
Center
UAB
WFUCT Reading Center
UAB CT
UMN CT
CT exams will be performed at the 4 Field
Centers 3,200 participants
San Francisco CT
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Lets 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

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Scales Require Calibration - So do CT Scanners!

• 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

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CT Phantom PartsSetup for Quality Control scans

• Other parts
• Blue cushion with insert for QCT phantom
• Gel bag (goes b/t patient and phantom)
• Made by Image Analysis

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Why are we scanning the Torso QCT phantoms?

• To make sure your CT scanners 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

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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.

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QA Scanner Setup
This should be at isocenter using your laser
alignment system
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QA procedure twice a month1st 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 (rois) on scanner
• 4 along bottom 1 center plug
• Record on QA sheet in your CARDIA CT notebook
• Fax to Reading Center (fax [phone])

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Example CT System data entry for QCT Torso
Phantom

• Name QC UAB
• ID number UABYYMMDD

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When the phantom is scanned on April 1st 2005 at
UAB

• Name QC UAB
• ID number UAB050401
• (or UI050401, UMN050401, WC050401)

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When the phantom is scanned on April 15th 2005 at
UAB

• Name QC UAB
• ID number UAB050415

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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

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CT Scan of heart with QCT phantom
QCT phantom with 4 tubes
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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)

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Example CT System data entry demographic fields

• Name ABCDE160
• ID number 12345
• Date of Birth 03 MAR 1947
• Weight 160 lbs
• Technologist 51
• Referring Physician Marcus Welby
• Indication CARDIA y20

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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)

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CT scan completion Form 76
Acrostic to replace real name
Study ID
DOB Gender
Weight
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CT Eligible
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CT scan completion Form 76
CT Tech ID
Let us know any problems!
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CT Scanning overview

• Scouts - Thoracic
• Frontal
• Lateral (optional)
• Heart 1 w/ ECG gating
• Heart 2 w/ ECG gating

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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..)

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Breathholding

• Script
• Take a deep breath in ltpausegt
• blow it all the way out ltpausegt
• Take a deep breath in ltpausegt
• blow it all the way out ltpausegt
• Take a deep breath in and hold it.
• Scan 20-40 seconds
• Breath and relax

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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

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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.

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ECG Lead placement

• Arms overhead
• Reposition leads if necessary
• Make sure amplitude (i.e. size) is OK per your CT
  scanner instructions

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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 _at_ 80 (636-736)
• Siemens at 50-TBD, (428, 755)
• GE at 70 ( 437-763)

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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 !!!!!!!!

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Scouts QCT Position Landmarks for Prescribing
Scans
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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

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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

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Weight and mAs

• If the weight is less than 220 lbsSet mAs
  Standard
• If the weight is 220 lbs or greaterSet mAs
  Standard1.25

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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

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Check and make adjustments after the first
scan!!!!!!!!!!!
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Preparing for Heart2
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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
• Dont do a third scan!!! This will result in
  increase radiation exposure to the participant!!!

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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

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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 ORourke
• jtan_at_wfubmc.edu
• corourke_at_wfubmc.edu 336 716 8909
• Main 336.716.7234
• Send Entire Exam
• Heart 1
• Heart 2
• Additional reconstructions

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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)

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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

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Homework

• Copy of CT systems last full calibration by
  field engineer of physicist and send to us
• Verify reconstruction thickness
• Program CARDIA Y20 protocol into CT scanner