Apparatus and method for acquiring sectional images

A computer implemented method of controlling an imaging system to provide a sectional image of a body, the method comprising the steps of:

• defining a reference surface corresponding to a control surface having a pre-determined relationship with the body, with respect to which control surface a sectional image through a particular portion of the body is generatable by the imaging system;
• providing an interrogation window lying in a movable interrogation plane intersecting the reference surface, wherein translation and/or rotation of the interrogation plane provides a corresponding movement of the interrogation window;
• said interrogation plane being associated with a pole, which lies in the interrogation plane, about which pole said interrogation plane is rotatable, and for each movement of the interrogation plane, determining the point of intersection of said pole and said reference surface, determining the relative angle of rotation of said interrogation plane about said pole and determining the angle of inclination of said pole to said reference surface;
• and
• on the basis of said pre-determined relationship and said determinations, providing a sectional image through the body, the sectional image corresponding to the relative position and orientation of the interrogation window to the reference surface,
• wherein said interrogation plane has two or three degrees of rotational freedom and two degrees of translational freedom such that said interrogation plane is only translatable across said reference surface.