An amino acid analog is provided, in syn-stereoisomeric form, anti-stereoisomeric form, or a combination thereof. The amino acid analog includes a cyclobutane ring with at least one of an amine group and a carboxyl group attached to one carbon node of the cyclobutane ring. A chain of moieties X, Y, and Z attached to one of remaining three carbon nodes of the cyclobutane ring. X is a chelating agent selected from a group comprising DCTA, DOTA, DTPA, EDTA, NOTA, PCTA, and TETA. Y is a linking moiety selected from a group comprising —NH—CO— and —NH-p-CHSN-Bn- where the linking moiety facilitates incorporation of the chelating agent into the amino acid analog. Z is a metal radioisotope selected from a group comprising Cu-60, Cu-61, Cu-62, Cu-64, Cu-67, Ga-67, Ga-68, Y-86, Y-88, Y-90, Sr-85, Sr-89, Gd-153, Gd-157, Sm-153, Lu-177, W-185, Re-186, Re-188, and Ir-192.
