Impact of acuros XB algorithm in deep-inspiration breath-hold (DIBH) respiratory techniques used for the treatment of left breast cancer.

AIM: To investigate the impact of Acuros XB (AXB) algorithm in the deep-inspiration breath-hold (DIBH) technique used for treatment of left sided breast cancer. BACKGROUND: AXB may estimate better lung toxicities and treatment outcome in DIBH. MATERIALS AND METHODS: Treatment plans were computed using the field-in-field technique for a 6 MV beam in two respiratory phases - free breathing (FB) and DIBH. The AXB-calculations were performed under identical beam setup and the same numbers of monitor units as used for AAA-calculation. RESULTS: Mean Hounsfield units (HU), mass density (g/cc) and relative electron density were -782.1 ±â€¯24.8 and -883.5 ±â€¯24.9; 0.196 ±â€¯0.025 and 0.083 ±â€¯0.032; 0.218 ±â€¯0.025 and 0.117 ±â€¯0.025 for the lung in the FB and DIBH respiratory phase, respectively. For a similar target coverage (p > 0.05) in the DIBH respiratory phase between the AXB and AAA algorithm, there was a slight increase in organ at risk (OAR) dose for AXB in comparison to AAA, except for mean dose to the ipsilateral lung. AAA predicts higher mean dose to the ipsilateral lung and lesser V20Gy for the ipsilateral and common lung in comparison to AXB. The differences in mean dose to the ipsilateral lung were 0.87 ±â€¯2.66 % (p > 0.05) in FB, and 1.01 ± 1.07% (p < 0.05) in DIBH, in V20Gy the differences were 1.76 ±â€¯0.83% and 1.71 ±â€¯0.82% in FB (p < 0.05), 3.34 ± 1.15 % and 3.24 ± 1.17 % in DIBH (p < 0.05), for the ipsilateral and common lung, respectively. CONCLUSION: For a similar target volume coverage, there were important differences between the AXB and AAA algorithm for low-density inhomogeneity medium present in the DIBH respiratory phase for left sided breast cancer patients. DIBH treatment in conjunction with AXB may result in better estimation of lung toxicities and treatment outcome.