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Dosimetric accuracy of proton therapy for chordoma patients with titanium implants
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10.1118/1.4810942
/content/aapm/journal/medphys/40/7/10.1118/1.4810942
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/40/7/10.1118/1.4810942

Figures

Image of FIG. 1.
FIG. 1.

Cross section of the tissue characterization phantom used to study CT metal artifacts. The phantom consists of a disk of solid water in which various tissue-equivalent plastics are inserted. One scan was obtained with two titanium cylinders in the positions indicated; a second ground truth scan was acquired without the titanium cylinders. The dashed lines indicate the beam angles used in the study.

Image of FIG. 2.
FIG. 2.

Phantom dose calculations of three proton beams passing through different parts of a metal artifact. The dose is calculated on the artifact-affected CT scan with titanium cylinders and the ground truth scans without artifacts. The ground truth scan includes a virtual titanium cylinder matching the physical one. Doses below 0.5% of the SOBP dose are not shown. CT window level: 40 HU and window width: 400 HU. (a) Beam perpendicular to main artifact; (b) beam through one titanium insert; and (c) beam parallel to main artifact.

Image of FIG. 3.
FIG. 3.

Dose calculations of a posterior–anterior proton beam passing through titanium hardware in the lumbar spine. The dashed line near the end-of-range of the beam is drawn to guide the eye. Doses below 0.1 Gy RBE are not shown. CT window level: 40 HU and window width: 400 HU.

Image of FIG. 4.
FIG. 4.

Dose calculations of a proton beam around titanium hardware in the cervical spine. The dashed line near the end-of-range of the beam is drawn to guide the eye. Doses below 0.1 Gy RBE are not shown. CT window level: 40 HU and window width: 400 HU.

Image of FIG. 5.
FIG. 5.

Total nonelastic nuclear reaction cross section of proton-induced reactions on titanium.

Image of FIG. 6.
FIG. 6.

Calculation of the loss of primary proton fluence due to nonelastic nuclear reaction in titanium, using the Wellisch and Axen (Ref. ) parametrization. A calculation using the nonelastic reaction cross section of titanium is compared to a calculation based on the cross section for water scaled by the relative proton stopping power of titanium.

Image of FIG. 7.
FIG. 7.

Dose calculations of a proton beam passing through a virtual uniform water phantom with a titanium cylinder. Doses below 0.5% of the SOBP dose are not shown.

Image of FIG. 8.
FIG. 8.

Dose calculations of a posterior–anterior beam passing through titanium orthopedic hardware. Doses below 0.5 Gy RBE are not shown. CT window level: 40 HU and window width: 400 HU.

Image of FIG. 9.
FIG. 9.

Original and corrected dose distributions of the treatment plan of patient 1. The difference between the two dose calculations is also shown. Doses and dose differences below 1 Gy RBE are not displayed. CT window level: 40 HU and window width: 400 HU.

Image of FIG. 10.
FIG. 10.

Original and corrected dose distributions of the treatment plan of patient 2. The difference between the two dose calculations is also shown. Doses and dose differences below 1 Gy RBE are not displayed. CT window level: 40 HU and window width: 400 HU.

Image of FIG. 11.
FIG. 11.

Dose–volume histograms of the patient dose distributions. Solid lines: dose calculations on the original CT scans using the pencil-beam algorithm; dashed lines: dose recalculations using metal artifact reduction and Monte Carlo simulations.

Tables

Generic image for table
TABLE I.

Details of the clinical CT scans and treatment plans.

Generic image for table
TABLE II.

Comparison of Geant4 model predictions of proton multiple Coulomb scattering in titanium to Molière theory calculations. The RMS angle of Gaussian fits to the angular distributions is listed.

Generic image for table
TABLE III.

Comparison of Geant4 simulations of multiple Coulomb scattering in titanium and a virtual high-density water medium with equivalent proton stopping power. The RMS angle of Gaussian fits to the angular distributions is listed.

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/content/aapm/journal/medphys/40/7/10.1118/1.4810942
2013-06-25
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Dosimetric accuracy of proton therapy for chordoma patients with titanium implants
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/40/7/10.1118/1.4810942
10.1118/1.4810942
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