Clinical and Plan Complexity Effects of Using Direct Aperture Optimization in Breast, Head and Neck IMRT Treatment | ||
| Egyptian Journal of Biomedical Engineering and Biophysics | ||
| Article 6, Volume 17, Issue 1, December 2016, Pages 67-79 PDF (483.72 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/ejbbe.2016.1590 | ||
| Abstract | ||
| TO INVESTIGATE the planning complexity and dosimetric impacts of direct aperture optimization (DAO) in IMRT treatment of breast, head and neck (H/N) cancers. Three breast and five H/N patients were planned using the beamlet optimizer in Elekta-Xio© ver 4.6 IMRT treatment planning system. Based on our experience in beamlet IMRT optimization, breast PTVs were prescribed to 50 Gy with 2 fields. While PTVs in H/N plans were prescribed to 70 Gy delivered by 7 fields.. In all plans, fields were set to be equally spaced. All cases were re-planed using Direct Aperture optimizer (DAO) in Prowess Panther© ver 5.01 IMRT planning system at same configurations and dose constraints. Plans were evaluated according to ICRU criteria, number of segments, number of monitor units and planning time. For H/N plans, the dose that covers 95% (D95) from PTV was 0.8% on average for plans done using beamlet optimizer more than that done using DAO, while D98%, D50% and D2% were higher in DAO plans than in beamlet optimizer by about 3%, 1%, and 2.2 %, respectively. For OAR, results showed an improvement in lung sparing in plans done using beamlet optimizer where V20 was lower by 12%. While DAO improved heart sparing than beamlet optimizer as V20 was lower 12%. These results achied using around less 45% segments number and 50% monitor units number as well. In DAO H/N plans, the near maximum dose (D2) and the dose that covers 95% (D95) of PTV has improved by 4% in DAO. For organs at risk (OAR), DAO reduced the volume covered by 30% (V30) inspinal cord, right parotid, and left parotid by 60%, 54%, and 53% respectively. This considerable dosimetric quality improvement achieved using 25% less planning time and lower number of segments and monitor units by 46% and 51%, respectively.DAO introduces considerable advantages over beamlet optimization in regards to organ at risk sparing. While no significant improvement occurred in the PTV ICRU reporting dose. | ||
| Keywords | ||
| DAO; IMRT; Optimization | ||
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