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Portal dosimetry for VMAT using integrated images obtained during treatment
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10.1118/1.4862515
/content/aapm/journal/medphys/41/2/10.1118/1.4862515
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/41/2/10.1118/1.4862515

Figures

Image of FIG. 1.
FIG. 1.

Measured (dotted lines) and predicted (solid lines) image profiles, (a) in the direction of MLC leaf motion and (b) orthogonal to the direction of MLC leaf motion, for a 10 × 10 cm field beyond various thicknesses of Solid Water.

Image of FIG. 2.
FIG. 2.

(a) Measured (circles, dotted lines) and predicted (squares, solid lines) image intensity at the center of the EPID for a range of field sizes and path lengths. (b) Measured (circles, dotted lines) and predicted (squares, solid lines) image intensity 3 cm (at isocenter) from the edge of the field for a range of field sizes and path lengths. The insets show the positions of the displayed image intensities. The field size axes refer to the length of side of the square field. The lines are merely to guide the eye: they are not intended to represent continuity of data. Note that for field size 20 × 20 cm, the image intensities shown in (b) are only 2.5 cm outside of the field, due to the limited size of the imaging panel, hence the discontinuity. The intensities are individual pixel values. The measured and predicted image intensities are not normalized to one another, but reflect the fit of the model to the measurements.

Image of FIG. 3.
FIG. 3.

Verification results for one of the esophagus cases. (a) Predicted portal image, (b) measured portal image, (c) gamma agreement between predicted and measured portal images with respect to 3% and 3 mm, (d) comparison of profiles through the predicted and measured portal images at = 0.

Image of FIG. 4.
FIG. 4.

Gamma histograms for the three lung, three esophagus, and three prostate cases.

Image of FIG. 5.
FIG. 5.

Dose-volume histograms for the perturbed treatment plans (solid lines) in relation to the correct treatment plans (dashed lines) for the lung cases. Each curve is the mean of the dose-volume histograms for the three treatment plans. In each case, the percentage, , of the integrated portal image with a gamma value, relative to 3% and 3 mm, of less than unity, is stated. The graph for E1 (top left) shows 1 SD of the curves for the correct treatment plans as an indicator of the uncertainty involved (dotted lines). CP: control point.

Image of FIG. 6.
FIG. 6.

Dose-volume histograms for the perturbed treatment plans (solid lines) in relation to the correct treatment plans (dashed lines) for the esophagus cases. Each curve is the mean of the dose-volume histograms for the three treatment plans. In each case, the percentage, , of the integrated portal image with a gamma value, relative to 3% and 3 mm, of less than unity, is stated. The graph for E1 (top left) shows 1 SD of the curves for the correct treatment plans as an indicator of the uncertainty involved (dotted lines). CP: control point.

Image of FIG. 7.
FIG. 7.

Dose-volume histograms for the perturbed treatment plans (solid lines) in relation to the correct treatment plans (dashed lines) for the prostate cases. Each curve is the mean of the dose-volume histograms for the three treatment plans. In each case, the percentage, , of the integrated portal image with a gamma value, relative to 3% and 3 mm, of less than unity, is stated. The graph for E1 (top left) shows 1 SD of the curves for the correct treatment plans as an indicator of the uncertainty involved (dotted lines). CP: control point.

Tables

Generic image for table
TABLE I.

Planned dose, ionization chamber verification results, and portal dosimetry results.

Generic image for table
TABLE II.

Results of the sensitivity analysis. All results are percentages of the image having a gamma value, relative to 3% and 3 mm, of less than unity, for a threshold of 10%.

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/content/aapm/journal/medphys/41/2/10.1118/1.4862515
2014-01-24
2014-04-21
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Portal dosimetry for VMAT using integrated images obtained during treatment
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/41/2/10.1118/1.4862515
10.1118/1.4862515
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