Comparison between hybrid direct aperture optimized intensity-modulated radiotherapy and forward planning intensity-modulated radiotherapy for whole breast irradiation.
OBJECTIVE
To investigate the planning efficiency and dosimetric characteristics of hybrid direct aperture optimized (hDAO) intensity-modulated radiotherapy (IMRT) compared with forward planning (FP)-IMRT for whole breast irradiation with two tangential beams.


METHODS
A total of 15 patients with left-sided breast cancer, categorized with three different breast volumes, were selected for this study. All patients were treated with FP plans to 50 Gy in 25 fractions. The hDAO plans were created by combining two open fields with eight segments in two tangential beam directions and were inversely optimized.


RESULTS
The FP and hDAO plans achieved similar breast coverage and sparing of critical organs. The volume of breast receiving 105% of the prescription dose was significantly smaller in the hDAO than in the FP plans: 25% vs. 63% (p = .008) for small, 22% vs. 57% (p = .005) for medium, and 28% vs. 53% (p = .005) for large breasts. Furthermore, the tumor cavity coverage was slightly better in the hDAO plans (92.4% vs. 90.9%).


CONCLUSIONS
Compared with FP-IMRT, hDAO-IMRT provided dosimetric advantages, significantly reducing the size of the hot spot and slightly improving the coverage of the tumor cavity. In addition, hDAO-IMRT required less planning time and was less dependent on the planner's ability.
Descovich
Martina
M
Department of Radiation Oncology, University of California San Francisco, School of Medicine, San Francisco, CA 94143-1708, USA.
Fowble
Barbara
B
Bevan
Alison
A
Schechter
Naomi
N
Park
Catherine
C
Xia
Ping
P
D000465:Algorithms; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D009929:Organ Size; D011832:Radiation Injuries / Q000517:prevention & control; D011859:Radiography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D047368:Tumor Burden