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<p>Since the publication of TG119 in 2009, new techniques have emerged in the field
of radiation therapy including VMAT (Volumetric Arc Therapy) and the FFF (Flattening
Filter Free) mode in Varian linear accelerators. Our goal in this work is to verify
the feasibility of using TG119 to test the commissioning of VMAT and FFF systems and
to set a benchmark for other institutions to use.</p><p>We created 48 plans of the
five sites given in TG119 in addition to a "real" HN case. For each site, we planned
IMRT and VMAT using 6MV and 10MV, FF and FFF modes (6*2*2*2 = 48 plans). All our plans
were created on the Eclipse treatment planning system (Varian Medical Systems, Palo
Alto, CA) and delivered on three beam-matched TrueBeam linear accelerators (Varian)
at Duke University Medical Center.</p><p>Measurements were taken using ion chamber,
film, and a pseudo-3D diode array (Delta4), and compared to the planned doses. Confidence
limits were determined using the approach of TG119 (CL = average mean deviation +
1.96 * standard deviation). We used the student's paired t-test to determine any statistically
significant differences between IMRT and VMAT, FF and FFF for 6MV and 10MV. </p><p>The
majority of the ion chamber measurements (94%) agreed with the planned doses within
3%. The majority of errors > 3% involved the HN IMRT plans, either TG119 or "real".
For film measurements, we used gamma parameters of 3%/3mm with a 20% threshold. All
films met Duke's acceptability criteria of <= 10% of pixels failing gamma. As for
Delta4, gamma parameters of 3%/3mm with a 5% threshold were used. All plans met Duke's
acceptability criteria of 90% of pixels passing (average 99.7% +/- 0.8%). A second
analysis was performed using 2%/2mm gamma parameters, where almost all plans met the
90% passing rate criteria (average 98.9% +/- 2.5%). </p><p>Confidence limits were
established for ion chamber (3.1%), film (6%), and Delta4 (3.1%) measurements. All
the confidence limits were comparable to TG119 institutions. We recommend that non-clinical
plans (e.g. 10MV HN plans) not be included in TG119 evaluations. We also recommend
that film continue to be used as the gold standard of multi-dimensional measurements,
rather than be replaced by diode-based technology.</p>
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