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Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy
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10.1118/1.3049787
/content/aapm/journal/medphys/36/2/10.1118/1.3049787
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/36/2/10.1118/1.3049787

Figures

Image of FIG. 1.
FIG. 1.

Sample analysis of a prostate cancer patient. The planning treatment volume (PTV) is shaded dark gray surrounding the prostate. Optimal treatment angles for split arc 180° proton therapy using two 90° arcs (method 1) are shown by the dashed curves. The optimal continuous 180° arc (method 2) is shown by the solid curve. The maximum pathlength from the surface of the patient to the distal edge of the treatment volume, , is shown for both methods 1 and 2.

Image of FIG. 2.
FIG. 2.

Sample analysis of a CT number profile taken along the maximum distance from the edge of the patient to the distal edge of the treatment volume, , in a lung cancer patient. The widths of each peak (valley) were measured at the full width at half-maximum (minimum). All density values were calculated from the corresponding CT number using CT number to density conversion tables found in the Pinnacle treatment planning system.

Image of FIG. 3.
FIG. 3.

Left: Geometry used to determine the neutron production by the intersection of a proton beam with a water phantom. (a) incident monoenergetic proton pencil beam; (b) water phantom; (c) cones’ vertex and shell’s center; (d) cone angles defined with respect to the central axis; (e1) and (e2) volume segments from the same cone-spherical shell intercept. Right: Additional view of the detecting volume created by the intercept of the cones with the spherical shell. The detecting volume is the region between the intercept of (a) and (b), labeled (c).

Image of FIG. 4.
FIG. 4.

Maximum proton kinetic energy necessary to treat patients. Data are representative of a set of 100 randomly selected radiotherapy patients treated at the UW Carbone Cancer Center (Madison, WI). The dashed curve represents continuous 180° arc proton therapy, while the solid curve allowed splitting of the 180° arc into two 90° arcs if doing so would decrease the necessary proton kinetic energy for treatment. The two disease sites most commonly treated with proton therapy, prostate and head and neck, are shown explicitly on the curve to highlight their separation in energy. The uncertainty in energy is less than 2%, and error bars were omitted for readability.

Image of FIG. 5.
FIG. 5.

Neutron energy spectra produced in a water phantom by incident monoenergetic proton pencil beams of varying energies. Spectra correspond to integrating the fluence over all emission angles. Data shown are the result of Monte Carlo simulations using the MCNPX transport code.

Image of FIG. 6.
FIG. 6.

Neutron energy spectra produced in a water phantom by incident monoenergetic proton pencil beams of varying kinetic energies. Spectra are shown for two different angular scattering regions and two different incident proton beam energies, as specified in the legend. Data shown are the result of Monte Carlo simulations using the MCNPX transport code.

Image of FIG. 7.
FIG. 7.

Total neutron energy fluence produced in a water phantom as a function of the kinetic energy of the incident monoenergetic proton pencil beam. The solid curve is a power fit of the data, showing the dependence of neutron production on incident proton kinetic energy. Data shown are the result of Monte Carlo simulations using the MCNPX transport code.

Tables

Generic image for table
TABLE I.

Summary of treatment site occurrence rates in the U.S., treatment sites included in this study, and patients in this study treatable at a proton kinetic energy of .

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/content/aapm/journal/medphys/36/2/10.1118/1.3049787
2009-01-08
2014-04-21
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/36/2/10.1118/1.3049787
10.1118/1.3049787
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