Transcript Electron Beam Tomography EBT - Oregon Institute of Technology

Electron Beam Tomography
EBT
I’ve never heard of it,
(and it doesn’t sound good)
• Electrons
– Atomic particles
– Have mass
• Wouldn’t a beam of particulate radiation
passing through the body be extremely
hazardous?
EBT does NOT pass an electron
beam through the patient
• The e- beam is
focused beneath
the patient at 4
stationary
tungsten targets
where X-rays are
produced
What is the radiation dose with
EBT?
• An advantage of the EBT scanner over
conventional scanners is instead of
exposing the entire circumference of the
body to the X-ray beam, the EBT X-ray
beam enters from the back. Thus, anterior
structures such as the breast and thyroid
are subjected to a lesser dose of radiation
(17% of the entrance skin dose). EBT
scanning is usually 1/5th to 1/10th the
radiation exposure as Spiral CT scanning.
Comparing Radiation Doses
EBT Coronary Calcium Scan
Standard Abdominal X-ray
Standard Coronary Angiogram
Background Sunshine
Radiation in 1 year
50 to 70 mrem
0.5 to 0.70 mSv
48 mrem
0.48 mSv
500 to 1000 mrem
5 to 10 mSv
300 mrem
3.0 mSv
How are EBT Images Obtained?
Due to the near constant motion of the heart, the
scans are triggered by the ECG signal at 80% of the
R-R interval, near end diastole before atrial
contraction, thus minimizing the effect of cardiac
motion.
Due to the lack of mechanical motion these scans
are fast enough to be shot during the moment the
heart is still.
Electron Beam Tomography
of the Heart
• Why was it done?
– EBTs were first used to find calcium buildup in
heart arteries, which can increase your risk for
coronary artery disease (CAD). It may be
used as a tool to find hardening of the arteries
in people who have a high chance of
developing atherosclerosis
What do cardiac EBTs Show?
• The most significant finding of an EBT
exam is the amount of calcified plaque
in your coronary arteries. Calcified
plaque in the coronary arteries is easy
to see on an EBT scan because it has
become hard and dense.
CAD in the US
The well-known risk factors for heart disease:
•high cholesterol
•high blood pressure
•diabetes
can be useful for indicating how healthy a heart
is. But they don't tell the whole story; even if you
don't have any known risk factors, you could still
be at risk.
CAD in the US
For 450,000 Americans each year the very
first symptom of a heart problem is a sudden
heart attack. For one-third of them, that first
attack is fatal. That's what makes an EBT
imaging study so valuable. It is the first and
only screening test approved by the Food and
Drug Administration that can actually look
inside the heart.
Calcified Plaque and MI
• A heart attack happens when plaque
ruptures in your coronary arteries, leading
to the sudden blockage of blood flow to
the heart. There's a well-established
relationship between coronary plaque and
calcified plaque. If you have more of one,
you'll have more of the other. Due to this
association, EBT is the most definitive
method available for detecting early stage
coronary-artery disease.
The Progression of an Acute MI
Coronary artery calcification is part of the development of atherosclerosis; it occurs
exclusively in atherosclerotic arteries and is absent in the normal vessel wall.
Who Should Have a EBT?
• An EBT exam is recommended if you are
a man between the ages of 40 and 70 or a
woman between 45 and 75. It is
particularly recommended if you have
other risk factors for heart disease such as
high cholesterol, high blood pressure, a
history of smoking, diabetes or a family
history of heart disease.
How Long Will the Test Take?
EBCT serial transaxial images are obtained in
100 ms with a scan slice thickness of 3 to 6
mm. 30 to 40 adjacent axial scans usually are
obtained. The rapid image-acquisition time
virtually eliminates motion artifact related to
cardiac contraction.
A study for coronary calcium is completed within
10 to 15 minutes, requiring only a few seconds
of scanning time.
The Future of EBT
• Virtual Angiograms
– Due to the rapid progression of medical
software the reconstructed images are
becoming more and more detailed
3D Heart Reconstruction
A Virtual Angiogram - Flythrough
The Future of EBT
Beyond the Heart
• Bowel Scans
– Virtual Colonoscopy
– 3D Surface Scans
Bowel Scan - Surface
Bowel Scan with Polyp
A Virtual Colonoscopy
The Future of EBT
Beyond the Heart
• Lung Scans
• Bone Scans
• Sinus Scans
Lung Scan
Bone Density Scan
EBCT of the Sinuses