A method and system for constructing from volumetric CT or MRI scan data of a patient region, a virtual two-dimensional fluoroscopic image of the patient region as seen from a selected point in space are disclosed. In the roll holder device, first and second holder cores are inserted in respectively first and second ends of the tubular spool shaft. In general, speculative transfers will be enabled by default if system performance is more likely than not to be enhanced by using speculative transfers. Also provided are fluorogenic substrates or substrates comprising a colored dye or a chemical reagent effective to induce a color or pH change. The storage unit stores screen information comprising icons related at least to the applications, disposition information of the icons on the screens, and acquisition source information for the applications. The polarization film is disposed on the incidence surface.