-\subsubsection{segment}
-Segments are the segments of a circle between a chord and the
-perimeter of the circle. This also isn't clear to me, but it appears that
-perhaps the distance from chord to circle perimeter, and circle radius is
-defined by dx and dy. Chord is always horizontal through the origin, then
-translated and then rotated (???).
-
-\subsection{Phantom Size}
-Also note that the overall dimensions of the phantom are increased by 1\%
-above the specified sizes to avoid clipping due to round-off errors.
-So, if the phantom is defined as
-a rectangle of size 0.1 by 0.1, the actual phantom has extent 0.101
-in each direction.
-
-\section{Scanner}\label{conceptscanner}\index{Concepts,Scanner}%
-\subsection{Sizes}
-Understanding the scanning geometry is the most complicated aspect
-of using \ctsim. For our real-world CT simulators, this is actually
-quite simple. The geometry is fixed by the manufacturer during
-the construction of the scanner and can not be changed.
-\ctsim, being a very flexible simulator,
-gives tremendous options is setting up the geometry for a scan.
-
-In general, the geometry for a scan all starts from the size of the
-phantom being scanned. This is because \ctsim\ allows for statistical
-comparisons between the original phantom image and it's reconstructions.
-Since CT scanners scan a circular area, the first important
-variable is the diameter of the circle surround the phantom, or the
-\emph{phantom diameter}. Remember, as mentioned above, the
-phantom dimensions are also padded by 1\%.
-
-The other important geometry variables for scanning objects are
-the \emph{view diameter}, \emph{scan diameter}, and \emph{focal length}.
-These variables are all input into \ctsim\ in terms of ratios rather than
-absolute values.
-
-\subsubsection{Phantom Diameter}
-The maximum of the phantom length and height is used to define the square
-that completely surrounds the phantom. Let
-\latexonly{$P_l$}\latexignore{\emph{Pl}}
-be the width and height of this square. The diameter of this boundary box,
-\latexonly{$P_d$,}\latexignore{\emph{Pd},}
-is then
-\latexignore{\\$$\emph{Pl x sqrt(2)}$$\\}
-\latexonly{$$P_d = P_l \sqrt{2}$$}
-CT scanners actually collect projections around a circle rather than a
-square. The diameter of this circle is also the diameter of the boundary
-square
-\latexonly{$P_d$.}\latexignore{\emph{Pd}.}
-These relationships are diagrammed in figure 1.
-
-\subsubsection{View Diameter}
-The \emph{view diameter} is the area that is being processed during scanning of phantoms as
-well as during rasterization of phantoms. By default, the \emph{view diameter}
-is set equal to the \emph{phantom diameter}. It may be useful, especially for
-experimental reasons, to process an area larger (and maybe even smaller) than
-the phantom. Thus, during rasterization or during projections, \ctsim\ will
-ask for a \emph{view diameter ratio},
-\latexonly{$V_{dR}$.}\latexignore{\emph{VdR}.}
-The \emph{view diameter} is then set as
-\latexonly{$$V_d = P_d V_{dR}$$}\latexignore{\\$$\emph{Vd = Pd x VdR}$$}
-
-By using a
-\latexonly{$V_{dR}$}\latexignore{\emph{VdR}}
+\subsubsection{View Diameter}\index{View diameter}
+The \emph{view diameter} is the area that is being processed
+during scanning of phantoms as well as during rasterization of
+phantoms. By default, the \emph{view diameter} is set equal
+to the \emph{phantom diameter}. It may be useful, especially for
+experimental reasons, to process an area larger (and maybe even
+smaller) than the phantom. Thus, during rasterization or during
+projections, \ctsim\ will ask for a \emph{view ratio},
+\latexonly{$v_r$.}\latexignore{\rtfsp \emph{VR}.} The \emph{view
+diameter} is then calculated as
+\latexonly{\begin{equation}v_d = p_dv_r\end{equation}}
+\latexignore{\\\centerline{\emph{Vd = Pd x VR}}\\}
+
+By using a
+\latexonly{$v_r$}\latexignore{\emph{VR}}