list of nuclear medicine radionuclides imaging systems...
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Miyaoka Summer 2006
Nuclear MedicineImaging Systems:
The Scintillation Camera
Miyaoka Summer 2006
List of Nuclear MedicineRadionuclides
• Tc99m 140.5 keV 6.03 hours• I-131 364, 637 keV 8.06 days• I-123 159 keV 13.0 hours• I-125 35 keV 60.2 days• In-111 172, 247 keV 2.81 days• Th-201 ~70, 167 keV 3.044 days• Ga-67 93, 185, 300 keV 3.25 days
From: Physics in Nuclear Medicine (Sorenson and Phelps)
Miyaoka Summer 2006
The Planar Gamma Camera
Siemens e.cam Miyaoka Summer 2006
Gamma Camera Instrumentation
Electronicsboards
crystalLG
PMT
acquisitionand
processingcomputer
collimator
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The Scintillation Camera:Detector System
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Crystal and light guide
NaI(Tl)Density 3.67 g/cm3
Attenuation Coefficient (@140 keV) 2.64 cm-1
PE fraction ~80%Light output 40K/MeVDecay time 230 nsecWavelength 410 nm
Crystal
LightGuide
3/8” thick
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Detection Efficiency
0.64
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Light response function versus position(spatial resolution)
x
E
x7x6x5x4x3x2x1
!
ˆ x =
xi "Eii
#
Ei
i
#
CrystalLG
PMT
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Spatial Positioning
From: The Essential Physics of Medical Imaging (Bushberg, et al) Miyaoka Summer 2006
Techniques to optimize shape of lightresponse function
Siemens Medical Solutions product literature
Miyaoka Summer 2006
Scatter
detector - NaI(Tl)
PMTs
All scatter counts are within the object (unlike in PET)Miyaoka Summer 2006
Gamma Camera Energy Spectra
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0
1 104
2 104
3 104
4 104
5 104
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0 50 100 150 200
Nai(Tl) Energy Spectra (140 keV)
10% ER20% ER
Coun
ts
energy (keV)
Gamma Camera Energy Spectra
140 keV photons, 9.5 mm crystalMiyaoka Summer 2006
The Scintillation Camera:Collimators
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Parallel Hole Collimator
detector - NaI(Tl)
PMTs
le
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Collimators - Septal Penetration
!
t "
6dµ
l # 3µ( )
Minimum septa thickness, t,for <5% septal penetration:
From: Physics in Nuclear Medicine (Cherry, Sorenson and Phelps)
Detector
l
d t
Collimatorsepta
Miyaoka Summer 2006
Collimator Efficiency
Collimators typically absorb wellover 99.95% of all photons emittedfrom the patient.
Trade-off between spatialresolution and detection efficiency.
Miyaoka Summer 2006From: The Essential Physics of Medical Imaging (Bushberg, et al)
Collimator Resolution
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Gamma Camera - spatial resolution
!
Rs= R
i
2 + Rc
2( )
From: Physics in Nuclear Medicine (Cherry, Sorenson and Phelps) Miyaoka Summer 2006
Types of Collimators
From: The Essential Physics of Medical Imaging (Bushberg, et al)
magnification
Miyaoka Summer 2006From: Physics in Nuclear Medicine (Cherry, Sorenson and Phelps)
Collimator: Resolution and Sensitivity
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Collimator: Resolution and Sensitivity
From: The Essential Physics of Medical Imaging (Bushberg, et al)
Miyaoka Summer 2006
The Scintillation Camera:Corrections and QA
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Gamma Camera Processing Electronics(energy correction)
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1 104
2 104
3 104
4 104
5 104
6 104
0 50 100 150 200
Energy channel vs. event location
10% ER (between)10% ER (over)
Co
un
ts
energy (keV)
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Gamma Camera Processing Electronics(with and without energy correction)
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Gamma Camera Processing Electronics(linearity correction)
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From: Physics in Nuclear Medicine (Cherry, Sorenson and Phelps)
Miyaoka Summer 2006
Gamma Camera Processing Electronics(linearity correction)
Miyaoka Summer 2006
Additional Gamma Camera Correction(sensitivity / uniformity)
Acquired from long uniform flood after energy andlinearity corrections have been applied
Multiplicative correction
Adjusts for slight variation in the detection efficiencyof the crystal
Compensates for small defects or damage to thecollimator
Should not be used to correct for large irregularities
Miyaoka Summer 2006
Daily Gamma Camera QA Tests
Photopeak window
Flood uniformity
From: The Essential Physics of Medical Imaging (Bushberg, et al) Miyaoka Summer 2006
Multienergy spatial registration (e.g., Ga-67 (93-, 185-, and 300 keV) gamma rays)
From: The Essential Physics of Medical Imaging (Bushberg, et al)
properly adjusted improperly adjusted
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Spatial Resolution Test
From: The Essential Physics of Medical Imaging (Bushberg, et al)
FWHM of LSF = 1.7 x (size of smallest bar resolved)Miyaoka Summer 2006
Pulse Pile-up
From: Physics in Nuclear Medicine (Sorenson and Phelps) and (Cherry, Sorenson and Phelps)
Energy spectra
Pile-up in image
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The Scintillation Camera:Image Acquisition
Miyaoka Summer 2006
Image Acquisition• Frame mode (data stored as an image)
- static- single image acquisition- can have multiple energy windows
- dynamic- series of images acquired sequentially
- gated- repetitive, dynamic imaging- used for cardiac imaging
• List-mode (data stored event by event)- time stamps are included within data stream- allows for flexible post-acquisition binning- can result in very large data files
Miyaoka Summer 2006
Gated Acquisition
From: The Essential Physics of Medical Imaging (Bushberg, et al) Miyaoka Summer 2006
Region of Interest (ROI) and Time-ActivityCurves (TAC)
From: The Essential Physics of Medical Imaging (Bushberg, et al)