Wedge Angle and Hinge Angle

Making dose in an overlap region uniform:

This can occur by wedging the two fields, choosing the proper wedge angle that would make the isodose lines parallel to one another in the overlap region.

Finally this can be performed by correcting for surface obliquity if or after wedging the fields.

NOTE:

For a given hinge angle, there is a wedge angle for a wedge pair of fields that would make the dose uniform in the beam overlap region.

This assumes that the incident surface is normal to the central axis. If the patient surface is sloping, either compensator should be made use of or the wedge angle, derived from hinge angle should be adjusted to take into account the hinge angle.