The present invention refers to highly functionalised spiro-fused azetidinones of formula I:having a cyclohexane moiety with the desired number of protected or unprotected hydroxyl groups which are introduced with high stereo and regioselectivity, as well as processes for their synthesis. The base ends of the actuators are fixed to a support member. This arrangement realizes a radiation detector which suppresses radiation made incident on the signal processing means located downstream of the wiring substrate.