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Comparison of dose calculation algorithms in phantoms with lung equivalent heterogeneities under conditions of lateral electronic disequilibrium
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10.1118/1.1788932
/content/aapm/journal/medphys/31/10/10.1118/1.1788932
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/31/10/10.1118/1.1788932

Figures

Image of FIG. 1.
FIG. 1.

Diagram of the studied phantom.

Image of FIG. 2.
FIG. 2.

PDDs for the lung substitute commercialized by CIRS, measured with TLD (엯) and various ionization chambers obtained by Monte Carlo simulations (black thick continuous line) and predicted by the five studied calculation algorithms (Batho, black thick dashed line; Modified Batho, gray thick dashed line; Equivalent TAR, black thin dashed line; Helax-TMS Pencil Beam, black thin continuous line; and Collapsed Cone, gray thick continuous line). The left column (a), (c), (e) corresponds to photons and the right (b), (d), (f) to photons. The top line (a), (b) shows PDD curves for a field size, the middle (c), (d) for a , and the bottom line (e), (f) for a field size.

Image of FIG. 3.
FIG. 3.

PDDs for the St. Bartholomew’s hospital lung measured with TLD (엯), with the ionization chamber , obtained by Monte Carlo simulations (black thick continuous line) and predicted by the three studied calculation algorithms (Batho, black thick dashed line; Mod Batho, gray thick dashed line; and Equivalent TAR, black thin dashed line). The left column (a), (c), (e) corresponds to photons and the right (b), (d), (f) to photons. The top line (a), (b) shows PDD curves for a field size, the middle (c), (d) for a , and the bottom line (e), (f) for a field size.

Image of FIG. 4.
FIG. 4.

Experimental beam profiles at depth for two field sizes( as thick lines, and as thin lines), for both and inside both phantoms (a) and (b). Phantom (a) is a homogeneous phantom of Plastic Water (black lines), and phantom (b) is the heterogeneous studied phantom, so the film lies inside the lung substitute material commercialized by CIRS (gray lines).

Image of FIG. 5.
FIG. 5.

Films (above), gray scale dose images (center) and 80% and 20% isodoses (below) for a transverse plane of a beam at depth in phantoms (a) and (b) described in Fig. 4. In the grayscale image, the penumbra area has been highlighted in dark, and its widening inside the lung equivalent material is clearly seen.

Tables

Generic image for table
TABLE I.

Physical dimensions of the detectors used in this study.

Generic image for table
TABLE II.

Values of used in this work.

Generic image for table
TABLE III.

Average deviation (%) from the experimental reference (ionization measurements) of all the studied algorithms and the Monte Carlo simulations in the water equivalent part of the phantom. The results for the two studied lung equivalent materials, i.e., CIRS and Saint Bartholomew (SB), are shown for the four correction-based algorithms [Batho, Modified Batho (Mod Batho), Equivalent TAR (EqTAR) and Helax-TMS Pencil Beam (Helax-TMS PB)], for the convolution-superposition one [Collapsed Cone (CC)] and for the Monte Carlo simulations (MC).

Generic image for table
TABLE IV.

Average deviation (%) from the experimental reference (TLDs) of all the studied algorithms and the Monte Carlo simulations in the lung equivalent part of the phantom. The results for the two studied lung equivalent materials, i.e., CIRS and Saint Bartholomew (SB), are shown for the four correction-based algorithms [Batho, Modified Batho (Mod Batho), Equivalent TAR (EqTAR) and Helax-TMS Pencil Beam (Helax-TMS PB)], for the convolution-superposition one [Collapsed Cone (CC)] and for the Monte Carlo simulations (MC).

Generic image for table
TABLE V.

Beam penumbra measured by film and calculated by the TPS by means of the Cadplan Equivalent TAR algorithm (EqTAR), and by the Helax-TMS Pencil Beam (Helax-TMS PB) and Collapsed Cone (CC) algorithms for 6 and x-ray beams and four different square field sizes. The values obtained by means of the Monte Carlo simulations are also shown. The estimated uncertainty for each value was for the film measurements, for the TPS values and for the Monte Carlo simulations with the exception of the beam where it was due to the smaller voxel size.

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/content/aapm/journal/medphys/31/10/10.1118/1.1788932
2004-10-01
2014-04-18
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Comparison of dose calculation algorithms in phantoms with lung equivalent heterogeneities under conditions of lateral electronic disequilibrium
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/31/10/10.1118/1.1788932
10.1118/1.1788932
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