\documentclass[12pt]{article}
\usepackage{mtgreek}
\begin{document}
\[
\Gamma \Delta \Theta \Lambda \Xi \Pi \Sigma \Upsilon \Phi \Psi \Omega
\]
\italicupcasegreek
\[
\Gamma \Delta \Theta \Lambda \Xi \Pi \Sigma \Upsilon \Phi \Psi \Omega
\]
\uprightupcasegreek
\[
\Gamma \Delta \Theta \Lambda \Xi \Pi \Sigma \Upsilon \Phi \Psi \Omega
\]
\end{document}