X-Git-Url: http://git.kpe.io/?a=blobdiff_plain;f=doc%2Fctsim-concepts.tex;h=3f0bb1640554d5fe31f0415e017792f94566b778;hb=9c1565fc3c878d175983e34299aa5c4a7f0bb77c;hp=27d342a33b72062f926b846809afc8a727379829;hpb=fd5767a661183c8fd4197accc0e9eef3fb5474bc;p=ctsim.git diff --git a/doc/ctsim-concepts.tex b/doc/ctsim-concepts.tex index 27d342a..3f0bb16 100644 --- a/doc/ctsim-concepts.tex +++ b/doc/ctsim-concepts.tex @@ -2,7 +2,7 @@ \setheader{{\it CHAPTER \thechapter}}{}{}{\ctsimheadtitle}{}{{\it CHAPTER \thechapter}} \ctsimfooter -\section{Overview}\index{Conceptual overview} +\section{Conceptual Overview}\index{Conceptual overview} The operation of \ctsim\ begins with the phantom object. A phantom object consists of geometric elements. A scanner is specified and the collection of x-ray data, or projections, is @@ -18,7 +18,6 @@ concerned with are the \helprefn{phantom}{conceptphantom} and the \helprefn{scanner}{conceptscanner}. \section{Phantoms}\label{conceptphantom} -\subsection{Overview}\label{phantomoverview}\index{Phantom!Overview}% \ctsim\ uses geometrical objects to describe the object being scanned. A phantom is composed of one or more phantom elements. @@ -63,12 +62,12 @@ Of note, the commonly used phantom described by Shepp and Logan\cite{SHEPP74} uses only ellipses. \subsubsection{rectangle} -Rectangles use \texttt{cx} and \texttt{cy} to define the position of +Rectangles use \texttt{(cx,cy)} to define the position of the center of the rectangle with respect to the origin. \texttt{dx} and \texttt{dy} are the half-width and half-height of the rectangle. \subsubsection{triangle} -Triangles are drawn with the center of the base at \texttt{(cx,cy) +Triangles are drawn with the center of the base at \texttt{(cx,cy)} and a base half-width of \texttt{dx} and a height of \texttt{dy}. Rotations are then applied about the center of the base. @@ -100,7 +99,6 @@ defined as a rectangle of size 0.1 by 0.1, the phantom size is 0.101 in each direction. \section{Scanner}\label{conceptscanner}\index{Scanner!Concepts}% -\subsection{Dimensions} Understanding the scanning geometry is the most complicated aspect of using \ctsim. For real-world CT simulators, this is actually quite simple. The geometry is fixed by the manufacturer during the @@ -108,6 +106,7 @@ construction of the scanner and can not be changed. \ctsim, being a very flexible simulator, gives tremendous options in setting up the geometry for a scan. +\subsection{Dimensions} The geometry for a scan starts with the size of the phantom being scanned. This is because \ctsim\ allows for statistical comparisons between the original phantom image and @@ -212,7 +211,6 @@ significant distortions will occur. \subsection{Divergent Geometries}\label{geometrydivergent}\index{Equilinear geometry}\index{Equiangular geometry} \index{Scanner!Equilinear}\index{Scanner!Equiangular} -\subsubsection{Overview} For both equilinear (second generation) and equiangular (third, fourth, and fifth generation) geometries, the x-ray beams diverge from a single source to a detector array. @@ -359,10 +357,10 @@ by \ctsim. They are taken from the standard measurements used by Herman\cite{HERMAN80}. They are: \begin{itemize}\itemsep=0pt -\item[-]\textbf{$d$}\quad The normalized root mean squared distance measure. -\item[-]\textbf{$r$}\quad The normalized mean absolute distance measure. -\item[-]\textbf{$e$}\quad The worst case distance measure over a \latexonly{$2\times2$}\latexignore{\emph{2 x 2}} pixel area. -\end{twocollist} +\item[]\textbf{$d$}\quad The normalized root mean squared distance measure. +\item[]\textbf{$r$}\quad The normalized mean absolute distance measure. +\item[]\textbf{$e$}\quad The worst case distance measure over a \latexonly{$2\times2$}\latexignore{\emph{2 x 2}} pixel area. +\end{itemize} These measurements are defined in equations \ref{dequation} through \ref{bigrequation}. In these equations, $p$ denotes the phantom image, $r$ denotes the reconstruction