\documentclass[12pt]{article}
\usepackage{pstricks}
\begin{document}

\pspicture(0,0)(12,12)


\psarc(5,5){1}{180}{270}


\pscustom[fillstyle=solid,fillcolor=lightgray]{
     \psline(11,5)(5,4)
     \psarc(5,5){1}{180}{270}
     \psline(4,5)(6,11)
     }     


\pscircle[linewidth=2pt,linestyle=dotted,fillstyle=solid,fillcolor=white](5,5){1}

\endpspicture

\end{document}

