Implementation of Beam's Eye View into routine treatment planning and delivery

The use of oblique fields in the chest and abdomen is fraught with uncertainty, especially in the location of critical structures on simulator and port films. Targets near these structures may be underdosed because of the physician's uncertainty in shaping the treatment fields. To help alleviate this problem, we have found the Beam's Eye View option of the Theraplan Treatment Planning System to be a useful and effective tool. The Beam's Eye View program uses the external and internal contours we enter into the treatment planning system from CT scans. Once the necessary contours have been entered from the desired CT slices, the software will project the view that the beam would see as it passes through these structures. Using this "Beam's Eye View," we can determine the optimum angle and field shape to treat our target and minimize critical structure dose.