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Research Stralingswetenschappen NGMB
University Medical Center Groningen

The microPET, microSPECT and microCT scanners

Siemens microPET Focus 220
Siemens microPET Focus 220


An area for animal experiments has been created in the basement of the Department of Nuclear Medicine & Molecular Imaging (NMMI) of the UMCG.

The imaging devices available are a microPET, microCT and a microSPECT.

The same rodent bed fits into all scanners, thus metabolic and anatomic information (PET or SPECT and CT images) can be easily combined.


Parameters of the Siemens microPET Focus 220 scanner for small animals:


Detector diameter (cm)


Effective opening (bore) (cm)

22 (26 cm with shields removed)

Transaxial Field of View (FOV in cm)


Axial Field of View (cm)


Number of detector blocks


Total number of LSO elements


Pixel element size(mm3)

1.5 x 1.5 x 10

Absolute system sensitivity (%)


Resolution at center of FOV (mm)

< 1.3

Average energy resolution (%)

< 18

Volumetric resolution (center FOV) (µl)

< 2.5

Volumetric resolution (central 8 cm) (µl)

< 9

Variable timing window:

2, 6, 10, 14 ns

Variable energy window:

0 – 814 keV

Set of 2D and 3D reconstruction algorithms


Computer controlled bed


Attenuation correction


Deadtime correction


Scatter correction


Decay correction for the most applied radionuclides


Dynamic framing

(from 1 ms to static)

Respiratory and cardiac gating


Interchangeable beds for mice and rats



For data acquisition, sinogram and image analysis, various software packages are available.

A Siemens Imtek MicroCAT II (small animal CT scanner) is placed in the same room as the microPET Focus 220. The CT is installed in a fully shielded cabinet x-ray system as defined by FDA Standard 21, CFR 1020.40. Parameters of that system are:


X-ray source

SourceRay SB-80-50

Maximum Potential

80 kVp

Maximum current

0.5 mA

Anode material


Focal spot size

~ 40 µm

Beam filtration

0.25 – 2 mm Aluminium

Duty cycle

100 %


The gantry port is configured with lasers to draw calibrated x,y,z fiducial markers on the animal for easy positioning. X-ray dose depends on many factors but for a typical whole animal scan of 360 steps (rat) the delivered dose is < 10 cGy.

The detector is a CCD camera with 2048 x 3072 pixels and 5 frame per second read out with 2x2 binning. Dynamic range: 69 dB with 1 x 1 binning and 72 dB with 2 x 2 and 4 x 4 binning.


Standard position

57 x 85 mm2 FOV


37 µm resolution

High resolution position

31 x 47 mm2 FOV


27 µm resolution


The microCAT reconstruction software package is based on a modified Feldkamp algorithm weighted for either 180-degree plus cone-beam or 360-degree studies. The microCAT system has been delivered with the Amira Advanced 3D Visualization and Volume Modelling package.


Micro-SPECT system based on a stationary detector set-up, resulting in:

  · high mechanical stability

  · low maintenance

  · high up time


 Quantitative image reconstruction software

 Sub-minute temporal resolution

 Energy range 20-400 keV

 List mode acquisition


 Reconstructed resolution down to:

  · 0.6 mm (standard mouse collimator)

  · 1 mm (rat collimator)


Return to microPET menu 


Siemens Imtek MicroCAT II
Siemens Imtek MicroCAT II
MiLabs MicroSPECT II
MiLabs MicroSPECT II
Laatst gewijzigd:23 november 2012 10:21