Reasoning and discussion of spiral CT localization formula / 医疗卫生装备

ABSTRACT

Using geometry principle of the spiral CT localization , functional relation was deduced between the bed coordinates and the diagram layers coordinates, i.e.when gantry angle is zero degree, the function relation type is Twm= S190/Cos? + M; Otherwise, it is Twm= S190/Cos? +M. Combined with the actual operation of CT localization, the formula of the CT localization is:Twm=S190/Cos?+M. Finally, the physical meaning and the simplified condition of the formula were discussed.