Improvement of dose distribution with irregular surface compensator in whole breast radiotherapy

Aim of this study was to compare the dosimetric aspects of whole breast radiotherapy (WBRT) between an irregular surface compensator (ISC) and a conventional tangential field technique using physical wedges. Treatment plans were produced for 20 patients. The Eclipse treatment planning system (Varian Medical Systems) was used for the dose calculation: For the physical wedge technique, the wedge angle was selected to provide the best dose homogeneity; for the ISC technique, the fluence editor application was used to extend the optimal fluence. These two treatment plans were compared in terms of doses in the planning target volume, the dose homogeneity index, the maximum dose, ipsilateral lung and heart doses for left breast irradiation, and the monitor unit counts required for treatment. Compared with the physical wedge technique, the ISC technique significantly reduced the dose homogeneity index, the maximum dose, the volumes received at 105% of the prescription dose, as well as reducing both the ipsilateral lung and heart doses (P 0.05). Thus, the ISC technique for WBRT enables significantly better dose distribution in the planning target volume

Dosimetric comparison of irregular surface compensator and field-in-field for whole breast radiotherapy

Purpose: The purpose of the present study was to evaluate the dosimetric benefits of the irregular surface compensator (ISC) technique for whole breast radiotherapy compared with the field-in-field (FIF) technique. Materials and Methods: Radiotherapy was planned using both techniques in 50 breast cancer patients (25 left sided and 25 right sided). The Eclipse treatment planning system (Varian Medical Systems) was used for dose calculations. For the FIF technique, subfields were added to the main fields to reduce hot and cold regions; for the ISC technique, the fluence editor application was used to extend the optimal fluence. Planning target volume dose, dose homogeneity index (DHI), maximum dose, ipsilateral lung, and heart doses for the left breast irradiation and monitor unit (MU) counts required for treatment were compared between the two techniques. Results: Compared with the FIF technique, the ISC technique significantly decreased DHI values and volumes receiving >105% of the prescription dose, and increased volumes receiving >95% of the dose and MU count (P 5 Gy compared with the ISC technique (P 10, 20, and 30 Gy and the values of a mean dose did not differ significantly between the techniques (P > 0.05). Conclusions: The ISC technique is preferred over the FIF technique