Custom electron bolus treatment planning with skin collimation using the pencil-beam redefinition algorithm

ECT is defined as the use of one or more electron beams for the following purpose: (1) containing the planning target volume (PTV) in the 90% (of given dose) dose surface: (2) achieving as homogenous a dose as possible (e.g., 90% to 100%) or a prescribed heterogeneous dose distribution to the PTV; and (3) delivering a minimal dose to underlying critical structures and normal tissue [1]. ECT can be achieved through energy modulation Results cont. . The superior aspect of the patient plan using bolus ECT without skin collimation is illustrated in Figure 5. Due to the width of the beam penumbra and the proximity of the PTV to the eye, the lens and ocular orbit receive considerable dose compared to the plan with skin collimation in Figure 6. DVHs in Figure 7 show insignificant changes in the DVH of the PTV, but significant changes in the DVHs of the critical structures. For the lens, dose to the 10% volume is reduced from 24% (13 Gy) to 5% (3 Gy). For the ocular orbit, dose is reduced from