Imaging Diagnostic Systems Inc. announced it has signed a collaborative agreement with the Rumbaugh-Goodwin Institute for Cancer Research Inc., in Plantation, Fla., to develop optical imaging products for the laboratory market. Imaging Diagnostic Systems, also based in Plantation, makes the CTLM computed tomography laser breast imaging system, which uses laser technology and patented algorithms to create 3-D cross-sectional images of the breast.   . . .   Jeffrey Sinclair has been named the new western regional representative for Light Age Inc., a Somerset, N.J.-based developer of alexandrite laser technology for the industrial, scientific and medical markets. His sales territory will be California, Nevada, Arizona and Hawaii. He will concentrate on promoting Light Age's Epicare LP and LPX (hair removal) and Ta2Eraser (tattoo removal) lasers.