System of rules for the determination of level correlation between computerized tomograms and standard roentgenograms in irradiation planning

For topometric preparation of patients for CT irradiation it is neccessary to determine quickly and accurately the correlation between a CT-section and a certain level on standard roentgenograms. By using a special rule made of organic glass one can immediately determine a distance of the CT-level section from a given anatomical point even without definite anatomical orienting points at a given level. Such a rule makes it possible to correlate the level of an image on a computerized tomogram. Manipulations with rules do not practically influence the position of a patient on the table, neither do they result in artefacts during reconstruction of a CT-image