-This creates an image file from a phantom. Technically, it converts
-the phantom from a vector (infinite resolution) object into defined resolution
-image. The parameters to set are:
-
-x-size Number of columns in image file
-y-size Number of rows in image file
-samples Numbers of samples taken per pixel in the x and y directions.
- For example, if the nsamples is set to \texttt{3}, then for every
- pixel in the image file, 9 samples (3 x 3) are averaged.
+This creates an image file from a phantom. Technically, it
+converts the phantom from a vector (infinite resolution) object
+into a 2-dimension array of floating-point pixels. The parameters
+to set are:
+
+\begin{twocollist}
+%\twocolitemruled{\textbf{Parameter}}{\textbf{Options}}
+\twocolitem{\texttt{X size}}{Number of columns in image file}
+\twocolitem{\texttt{Y size}}{Number of rows in image file}
+\twocolitem{\texttt{Samples per pixel}}{Numbers of samples taken
+per pixel in both the x and y directions. For example, if the
+\texttt{Samples per pixel} is set to \texttt{3}, then for every
+pixel in the image file 9 samples (3 x 3) are averaged.}
+\end{twocollist}