Digital Signal Processing Reference
In-Depth Information
Signal
CsI Detector
Gamma
Camera
Projection-space
Filtering
Subject
CT & PET
Projection
Data
Cleaned Raw
Image Data
Filtered Back-
projection,
Iterative
Reconstration
Threshold
Filtering
3D PET/CT
Image(s)
Aligned CT/PET
Images
Nonrigid
Registration
Tumor
Segmentation
Fused Image
Visualization
Physician
Fig. 3
3D echocardiography is volumetric ultrasound imaging of the heart. The images
are used to study the health of the left ventricle of the heart by visually evaluating
the motion and structure of the ventricular wall and mitral valve over the entire
cardiac cycle. Quantitative information about the variation of the ventricular volume
and regional wall motion and thickness is important to make accurate diagnosis of
any underlying heart ailments. The block diagram in Fig.
2
shows the basic steps
involved in enabling this application.
Multimodality fusion of PET and CT images permits an accurate localization of
active tumors, shown unequivocally by PET, with respect to the detailed anatomic
map provided by CT. The precise identification and localization of active tumors
with respect to CT obtained is important for making a definitive diagnosis and
is playing an increasing role in image-guided therapies for the delivery of highly
conformal doses to the tumor, advancement of an interventional device to the tumor,
and monitoring treatment response in general. The diagram in Fig.
3
shows the basic
steps involved in enabling the fusion and display of PET and CT images.
The subsequent sections describe in more detail various algorithms that form all
the basic elements of imaging pipeline described in this section.
4
Image Reconstruction
Except for projection imaging techniques of conventional radiology and planar
scintigraphy, the tomographic imaging techniques introduced earlier acquire raw
data in a format that does not correspond directly and intuitively with the physical
