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(a) Example of the four‐field modified X beam configuration, with beam angles indicated with red arrows. (b) Example of the custom avoid structures created for each patient. “Post_Avoid” is applied to the posterior beams to avoid treating through the shoulders. The “Ant_Avoid” structure is the oral cavity, minus the target, plus any dental hardware plus an 8 mm expansion. The avoid is applied to the anterior beams to avoid beams treating through metal and to reduce oral cavity dose
