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[ctsim.git] / doc / ctsim-concepts.tex

diff --git a/doc/ctsim-concepts.tex b/doc/ctsim-concepts.tex
index 48386e6cb74b4ba015f53056c99f07dc613ef504..bd6bffbb32563ce68df9ec51b23ff895a2286abc 100644 (file)
--- a/doc/ctsim-concepts.tex
+++ b/doc/ctsim-concepts.tex
@@ -11,16 +11,18 @@ controlled algorithms producing an image of the phantom or study object.
 
 In order to use \ctsim\ effectively, some knowledge of how \ctsim\ works
 and the approach taken is required. \ctsim\ deals with a variety of
-object, but the two we need to be concerned with are the 'phantom' and
+object, but the two objects we need to be concerned with are the 'phantom' and
 the 'scanner'.
 
 \section{Phantoms}\label{conceptphantom}\index{Concepts,Phantoms}%
 \subsection{Overview}\label{phantomoverview}\index{Concepts,Phantoms,Overview}%
 
 \ctsim\ uses geometrical objects to
-describe the object being scanned: rectangles, triangles, ellipses,
-sectors and segments.  With these the standard phantoms used in the CT
-literature (the Herman and the Shepp-Logan) can be constructed.  In fact
+describe the object being scanned. A phantom is composed a one or more
+phantom elements. These elements are simple geometric shapes,
+specifically, rectangles, triangles, ellipses, sectors and segments.
+With these the standard phantoms used in the CT literature (the Herman
+and the Shepp-Logan) can be constructed.  In fact
 \ctsim\ provides a shortcut to construct those phantoms for you.  It also 
 allows you to write a file in which the composition of your own phantom is
 described.
@@ -49,7 +51,7 @@ Where objects overlap, the attenuations of the overlapped objects are summed.
 \subsubsection{ellipse}
 Ellipses use dx and dy to define the semi-major and semi-minor axis lengths,
 with the centre of the ellipse at cx and cy.  Of note, the commonly used
-phantom described by Shepp and Logan\cite{SHEPP77} uses only ellipses.
+phantom described by Shepp and Logan\cite{SHEPP74} uses only ellipses.
 
 \subsubsection{rectangle}
 Rectangles use