PMC6008825_01
Axial view CT and structures for both cases using CORT dataset: (a) TG-119 phantom; (b) prostate.
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fig2
In this case, two PTVs with prescribed doses of 56 and 68 Gy were defined, which were surrounded by the OARs of the rectum and bladder (Figure 2).
TG-119 phantom case. Comparison of axial dose distribution obtained in (a) optimal angle set plan (30 , 180 , and 285 ) and (b) equiangular plan (0 , 120 , and 240 ).
CMMM2018-4571801.004.jpg
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fig4
To show the effectiveness of the algorithm in reaching a better beam orientation, the dose distribution of the optimal plan was compared with equispaced beams as illustrated in Figure 4.
DVH comparison for TG-119 phantom case of equiangular and optimal beam angle set plans. Three coplanar 6 MV photon beams were used for both plans.
CMMM2018-4571801.005.jpg
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fig5
PMC6008825_02
Axial view CT and structures for both cases using CORT dataset: (a) TG-119 phantom; (b) prostate.
CMMM2018-4571801.002.jpg
PMC6008825_02_CMMM2018-4571801.002.jpg
fig2
In this case, two PTVs with prescribed doses of 56 and 68 Gy were defined, which were surrounded by the OARs of the rectum and bladder (Figure 2).
Comparison of DVHs of seven-beam angle selection plan and BAO algorithm plus seven-beam equiangular plan.
CMMM2018-4571801.006.jpg
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fig6
It was observed through several runs of the problem that some beam angles in the configuration changed slightly, but the overall objective function value did not change significantly (Figure 6) compared to the DVHs of the sets of seven optimal coplanar beams and seven equispaced beams.
Dose distributions for prostate case in axial, coronal, and sagittal views: (a) seven-angle equiangular plan (0 , 50 , 100 , 150 , 200 , 255 , and 305 ); (b) seven-angle optimal plan (5 , 50 , 110 , 200 , 225 , 260 , and 320 ); (c) five-angle optimal plan (5 , 105 , 185 , 210 , and 290 ).
CMMM2018-4571801.007.jpg
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fig7
These plans were optimized using the same dose prescription for the objective function.  Figure 7 shows the dose distributions and confirms that the BAO improved the quality of the plan in comparison with the equispaced method.
DVHs for the prostate case. Solid lines denote the five-beam plan generated by BAO algorithm. Dotted lines denote the results of the treatment plan with seven equiangular beams.
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fig8