Image Processing Techniques in Emission Tomography - Correction Techniques in Emission Tomography - page 149

(a) Input phantom (b) Simulated PET acquisition

FIGURE 7.16: Simulated PET acquisition using GATE. (a) Static XCAT
phantom used as input for simulation (1 mm 3 voxel size). (b) Result from
simulated PET acquisition using GATE. Simulated scan duration is 5 minutes.

7.7.2.2 Software

Software phantoms are helpful to develop and validate medical image pro-
cessing algorithms as they provide morphological (anatomy) and/or functional
(physiology) ground-truth information. In connection with software phantoms
the realistic simulation of scanner acquisition processes is discussed. Popular
phantoms in emission tomography are XCAT, NCAT, and MOBY which are
often combined with the simulation tool GATE.

XCAT, NCAT, and MOBY
The XCAT, NCAT, and MOBY phantoms [56] allow the generation of PET
images and attenuation maps. While XCAT and NCAT are based on human
data, MOBY is a mouse phantom. All phantoms provide a model of the sub-
ject's anatomy and physiology. It is possible to include respiratory and cardiac
motion resulting in 4D images. To simulate tracer dynamics the additional use
of time activity curves (TACs) is possible. The outcome is idealized noiseless
data.

GATE
GATE (Geant4 Application for Tomographic Emission) [31] is a Monte Carlo
simulation-based toolkit for generating simulated PET or SPECT data under
realistic acquisition conditions. For example source or detector movement and
source decay kinetics can be modeled. GATE is a pure simulation framework
and does not include any predefined patient models. The output of XCAT,
NCAT, or MOBY can be used as input for GATE to simulate a realistic scan-
ner acquisition. Figure 7.16 gives an example of a simulated PET acquisition
using GATE and the XCAT phantom.

Related work
The Zubal phantom [73] is a human head and torso phantom which is com-
monly used for many modeling and simulation calculations. It is a common
alternative to the XCAT and NCAT phantom.
A labeled whole-body atlas for mice is the Digimouse dataset [16]. The