1. Spectral CT Overview
Different materials have different absorption profiles depending on the incident x-ray energy
Spectral CT* uses this property to separate a multi-energy x-ray spectrum into components in order to distinguish different materials
Possible applications
Improved contrast visualization
Improved bone removal
Virtual non-contrast exams
Kidney stone differentiation
Lesion characterization
Plaque characterization
Molecular contrast agent visualization
Low-Energy
X-rays
High-Energy
X-rays
*Works-in-Progress: Pending commercial availability and regulatory clearance.

2. Spectral CT approaches
What is it?
Dose
Separation/Noise
FOV
Motion
Philips
Dual Scan
Scan object twice
Extra
better
Full
Non-moving
kV Switch
Switch kV during single rotation
Some Extra
Poor
Any object
Dual Tube
Tube 80 kv, Tube 140 kv ok
Small
Slow moving
Dual Detector
Double decker detector
Normal
Photon Counting
Count each photon & determine its energy
Less
best
Low-energy X-rays
High-energy X-rays E1 E2
E total
Total x-ray beam

3. Plaque characterization*
Improved Iodine Visualization*
Low Energy
High Energy
Virtual Non-Contrast Imaging*
Plaque characterization*
Simultaneous Multi Energy Detectors* Clinical Results Hadassah Medical Organization Jerusalem, Israel
*Works-in-Progress: Pending commercial availability and regulatory clearance.

4. Spectral CT - Photon Counting
Compton Scatter
Spectral analysis
Gd-high
Ca-low
I-low
I-high
Gd-low
Ca-high
Plastic
Water
Full Spectrum Image E1 E2 E3 E4 E5 E6 E7 E8
Photon counting may allow K-edge imaging (e.g. contrast only imaging) using a traditional CT source
*Works-in-Progress: Pending commercial availability and regulatory clearance.

5. Spectral CT- Issues to Adoption
Clinical evidence - only small pilot studies to date
Financial evidence - Cost vs. Reimbursement vs. Time
Alternative techniques
Potential Benefit Alternate technique
Improved iodine visualization 80 kV scanning
Iodine maps Color map conventional CTA
Contrast/bone separation Image processing
Virtual non-contrast Low dose non-contrast

6. Spectral CT- Philips Leadership
Spectral CT is an important area of fundamental research
Philips is leading the Spectral CT Revolution
Advanced clinical system*
Dual Decker Detector prototype
Over 1500 clinical exams on prototype since 2005
Advanced laboratory system*
2 Photon Counting prototypes
Initial phantom & animal scans shown at RSNA 2007
Advanced applications*
Spectral EBW prototype
Works with any spectral data
Advanced research network
15 global sites and growing
Calcified
plaque
Iodine
filled
vessels
*Works-in-Progress: Pending commercial availability and regulatory clearance.