DISCLOSURES Honorarium – Research / Advisor, Expert Services and Conferences in Nuclear Cardiology BMS, CVT, Astellas, Lantheus, PGx, IAEA Royalties – Publications in Nuclear Cardiology Springer-Verlag-Nuclear Cardiology and Correlative Imaging: a teaching file, NY, 2004 Lippincott Williams & Wilkins, - Nuclear Medicine teaching File, 2009 João V. Vitola, MD, PhD Cardiologist and Nuclear Medicine Physician Quanta Diagnostico Nuclear Curitiba - Brazil New Developments / Technologies / Protocols in NC
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DISCLOSURES
Honorarium – Research / Advisor, Expert Services and Conferences in Nuclear Cardiology
BMS, CVT, Astellas, Lantheus, PGx, IAEA
Royalties – Publications in Nuclear Cardiology Springer-Verlag-Nuclear Cardiology and Correlative Imaging: a teaching file, NY, 2004 Lippincott Williams & Wilkins, - Nuclear Medicine teaching File, 2009
João V. Vitola, MD, PhD
Cardiologist and Nuclear Medicine Physician
Quanta Diagnostico Nuclear
Curitiba - Brazil
New Developments / Technologies / Protocols in NC
• New Gamma Cameras: CZT technology
• New Perfusion Tracer for PET - BMS747158
To be discussed
Eliminates scintillation and photomultiplier tubes
• higher spatial resolution
• higher energy resolution
• smaller size
Provides:
• improved image contrast
• improved multi-isotope imaging
• faster scanning / lower dose scans
• more flexibility in scanner design
Cadmium Zinc Telluride (CZT) - Direct Conversion Technology whose time has come
NaI(Tl) Crystal
Limitation of Conventional SPECT
Only a small
portion of the NaI
Crystal is used to
view heart
Discovery NM 530c System Design Simultaneous Cardiac acquisition by all stationary detectors
Discovery NM 530c System Design
32 x 32 x 5 mm
Indirect vs. direct conversion
X-ray or g-ray
Q.E. 20%-80%
electronics
e e e
e e
e e e
e e e
e e e
e
Photosensor (PMT):
2000 photo-electrons
Noise (APD/PD)
Gain variation
Light transport
Light generation
Direct Indirect
Scintillator (e.g. NaI:Tl):
9000 photons @ 140 keV
X-ray or g-ray
electronics
e
h h
h
h h
e e e e
- cathode
+ anode
Noise
Charge generation
Charge transport
Assuming no other sources of noise,
Poisson statistics dictates energy resolution:
g energy light photo-electrons
g energy charge carriers
Direct Conversion (CZT):
30,000 photons @ 140 keV
CdZnTe Semiconductor
Energy Resolution
Energy resolution depends on
- Light output of scintillator
- Linearity & uniformity of scintillator
- Uniformity of light collection
- Quantum efficiency of PMT
- Electronic noise
Energy resolution can be improved by
- Better scintillator
- Better photosensor
- …
scintillator
lightguide
PMT
Energy Resolution for CZT is determined by:
- crystal quality
- incomplete charge collection
Energy resolution can be improved by:
- using perfect crystals
- measuring and correction defects
- compensating for incomplete charge collection:
- using signal shape
- using dual-sided readout:
CZT
Anger 9.5% 99mTc:
140 keV
123I:
159 keV
50 100 150 keV 200
point sources in air
Alcyone 6.0%
Anger 9.5% 99mTc:
140 keV
123I:
159 keV
50 100 150 keV 200
point sources in air
Alcyone 6.0%Alcyone 6.0%
Spatial Resolution
Resolution for PMT based system is determined by:
- Thickness of crystal (light spreading)
- Size of PMT
- Light output of scintillator
- Optimization of light spread function
- Position estimation algorithm
Spatial resolution can be improved by
- Segmenting scintillator
- Smaller (or multi-anode) photomultipliers
scintillator
lightguide
PMT
Resolution for CZT based system is determined by:
- anode pitch
- charge spreading
Spatial resolution can be improved (somewhat) by:
- using a smaller pitch
- using proportional readout
- more electronic channels
Not to scale
CZT
Discovery NM 530c System Design
Multiple-Pinhole Collimator Design
Front Back
Thick Pb septa
prevents crosstalk
between detectors
Tungsten 5mm pinhole inserts
provide high energy collimation
(I-123) and limits Pb x-rays (Tl-201)
Discovery NM vs. Ventri
Energy
Resolution
FWHM/Peak
Central
(mm)
Resolution
Tangential
(mm)
Radial
(mm)
Point
Kcts/min
Sensitivity
Phantom
Kcts/min
DNM
530c 5.7% 4.8 3.35 5.25 688 573
Ventri 9.4% 10.9 7.5 10.9 99.2 150
Ratio 1.65 2.27 2.24 2.08 6.94 3.82
19 pinholes
Normal Example
S-SPECT Discovery NM 530c
12 min stress/ 14 min rest 2 min stress/ 4 min rest
DNM 530c: Clinical Implications
• Fast 2-5 min acquisitions
– Increase patient throughput
– Increase protocol flexibility
– Increase patient comfort and convenience
– Decrease patient radiopharmaceutical dose
– Decrease patient motion
• Simultaneous dual isotope imaging (= 10 X sensitivity)
• Improve bad beat rejection and diastolic function measurement (due to list mode acquisition)
Multicenter Comparison between DNM530c & Standard Dual Detector Cameras: Objectives
(n=161)
• To determine diagnostic agreement between the new Discovery NM 530c (DNM530c) and standard dual detector cameras (S-SPECT) in patients with known or suspected CAD.
• The secondary goals included the strength of agreement on a per-vessel analysis, the image quality, and the correlation of automated rest and stress left ventricular ejection fractions (LVEF).
Patient Example: Normal (male 5’6” 176 lbs)
S-SPECT Discovery NM 530c
12 min stress/ 14 min rest 2 min stress/ 4 min rest