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Model-based dose calculations for 125I lung brachytherapy
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10.1118/1.4729737
/content/aapm/journal/medphys/39/7/10.1118/1.4729737
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/39/7/10.1118/1.4729737

Figures

Image of FIG. 1.
FIG. 1.

CT profiles for uncorrected and vsMAR corrected data for patient 5. The profile passes from lung to soft tissue through metallic artifact streaks near a seed.

Image of FIG. 2.
FIG. 2.

A portion of a CT image showing (a) no artifact correction, (b) metallic artifact correction (vsMAR), (c) simple threshold replacement on an uncorrected image (STR), and (d) simple threshold replacement on a metallic artifact corrected image (vsMAR + STR).

Image of FIG. 3.
FIG. 3.

Histogram showing the frequency of CT numbers in several patient CT phantoms. Of note is the separation of peaks at −50 HU, likely distinguishing adipose tissue from other soft tissues. Data from four of six patients are shown for readability.

Image of FIG. 4.
FIG. 4.

The three tissue assignment schemes used. Row heights not to scale. CT number boundaries (in HU) are indicated (e.g., for detailed scheme, yellow marrow includes CT numbers −50 to −19).

Image of FIG. 5.
FIG. 5.

Dose (and CT number) profile for patient 5 for calculations with the simple tissue assignment scheme applied to phantoms with vsMAR + STR correction, vsMAR + STR (with replacement value of 0 HU), STR correction alone, vsMAR correction alone, and no correction. The horizontal axis gives the position along the line shown in Fig. 6.

Image of FIG. 6.
FIG. 6.

CT image for patient 5 showing the line (going from 1 to 2) used for the dose profile in Fig. 5. The outlines for PTV05 and PTV20 are also shown.

Image of FIG. 7.
FIG. 7.

Dose volume histograms for patient 1 with various correction schemes in (a) PTV05 and (b) PTV20. Results for phantoms with vsMAR + STR correction, vsMAR correction, STR correction, and no correction are shown. The simple tissue assignment scheme is used.

Image of FIG. 8.
FIG. 8.

Dose volume histograms for patient 3 with various tissue assignment schemes in (a) PTV05 and (b) PTV20. The simple, moderate, and detailed tissue assignment schemes are applied to a vsMAR + STR corrected phantom.

Image of FIG. 9.
FIG. 9.

Dose profile for patient 5 showing doses in phantoms with vsMAR + STR correction with the simple, moderate, and detailed tissue assignment schemes as well as the TG43-sim dose. The horizontal axis gives the position along the line shown in Fig. 10.

Image of FIG. 10.
FIG. 10.

CT image for patient 5 showing the line (going from 1 to 2) used for the dose profile in Fig. 9. The outlines for PTV05 and PTV20 are also shown.

Image of FIG. 11.
FIG. 11.

Dose volume histograms comparing TG43-sim and calculations performed with phantoms obtained using vsMAR + STR correction and the simple tissue assignment scheme with dose scored in the local medium of each voxel (D m, m ) and dose scored in water voxels (D w, m ) for (a) patient 1—PTV05, (b) patient 4—PTV05, (c) patient 1—PTV20, and (d) patient 4—PTV20.

Image of FIG. 12.
FIG. 12.

Dose profiles for patient 5 (a) in PTV05 passing near seeds and (b) at the edge of PTV20 passing through mainly lung tissue. Doses are shown from TG43-sim and from calculations performed with phantoms obtained using vsMAR + STR correction and the simple tissue assignment scheme with dose scored in the local medium of each voxel (D m, m ) and dose scored in water voxels (D w, m ).

Tables

Generic image for table
TABLE I.

Elemental compositions and mass densities of tissues [from Woodard and White (Ref. 33) and White et al. (Ref. 34)]. Also shown are the mass attenuation [from XCOM (Ref. 26)] and mass energy absorption coefficients (calculated with EGSnrc user-code g) for 28 keV photons. Composition of air (for 40% relative humidity) is taken from TG-43 (Ref. 13).

Generic image for table
TABLE II.

CT number/mass density calibration data.

Generic image for table
TABLE III.

V100 and D90 for PTV05 and D90 for PTV20 for various artifact correction methods. For vsMAR, STR, and no corrections, the percent difference with vsMAR + STR correction is shown.

Generic image for table
TABLE IV.

V100 and D90 for PTV05 and D90 for PTV20 for various tissue assignment schemes. For moderate and detailed, the percent difference with simple is shown. All phantoms have vsMAR plus STR correction.

Generic image for table
TABLE V.

V100 and D90 for PTV05 and D90 for PTV20 from calculations of TG43-sim and for phantoms with vsMAR + STR correction and the simple tissue assignment scheme with dose scored in the local medium of each voxel (D m, m ) and dose scored in water voxels (D w, m ). The percent difference of TG43-sim from D m, m and D w, m calculations are also shown.

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/content/aapm/journal/medphys/39/7/10.1118/1.4729737
2012-06-27
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Model-based dose calculations for 125I lung brachytherapy
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/39/7/10.1118/1.4729737
10.1118/1.4729737
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