Validation of a virtual source model for Monte Carlo dose calculations of a flattening filter free linac
(a) Absolute output factors as a function of field size for FFF and conventional 6 MV beams as predicted by the TPS compared to measurement. (b) Difference in output factors, calculated minus measured.
Sample beam data: (a) PDD curve for 2 × 2 cm2 field, (b) cross-profiles for a 30 × 30 cm2 field for the FFF model.
Absolute dose difference between measured and calculated depth doses curves (100 cm source-surface distance) for the field sizes indicated for (a) FFF and (b) FF beams. Monte Carlo variance is set at 0.5%.
Comparison of calculated vs measured beam profiles for sample field sizes of (a) 2 × 2 cm2, (b) 5 × 5 cm2, (c) 10 × 10 cm2, (d) 15 × 15 cm2, (e) 20 × 20 cm2, and (f) 30 × 30 cm2 at 100 cm SSD and a depth of 5 cm. Criteria for gamma analysis are 2%/2 mm.
Beam setup for IMRT planning of a head and neck case showing sagittal and coronal color-wash maps (a) and dose volume histogram (b). The FFF beam is displayed as the dotted line, 6 MV solid.
Number of segments and monitor units needed for each treatment plan and the relative increase in each necessary to deliver the FFF plans.
Gamma analysis and absolute dose difference of individual beams for the IMRT plans. Percentage of points passing gamma analysis (γ < 1) at 3%/3 mm and 2%/2 mm for the individual beams of each plan.
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