Evaluation of plastic materials for range shifting, range compensation, and solid-phantom dosimetry in carbon-ion radiotherapy.

@article{Kanematsu2012EvaluationOP,
  title={Evaluation of plastic materials for range shifting, range compensation, and solid-phantom dosimetry in carbon-ion radiotherapy.},
  author={Nobuyuki Kanematsu and Yusuke Koba and Risa Ogata},
  journal={Medical physics},
  year={2012},
  volume={40 4},
  pages={
          041724
        }
}
PURPOSE Beam range control is the essence of radiotherapy with heavy charged particles. In conventional broad-beam delivery, fine range adjustment is achieved by insertion of range shifting and compensating materials. In dosimetry, solid phantoms are often used for convenience. These materials should ideally be equivalent to water. In this study, the authors evaluated dosimetric water equivalence of four common plastics, high-density polyethylene (HDPE), polymethyl methacrylate (PMMA… 

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References

SHOWING 1-10 OF 27 REFERENCES

The water equivalence of solid materials used for dosimetry with small proton beams.

To estimate the magnitude of this effect, flux and dose measurements with a 177 MeV proton pencil beam having a width of 0.6 cm (FWHM) were performed and the number of out-scattered protons due to inelastic nuclear scattering was determined for water and the different materials.

Fluence correction factors in plastic phantoms for clinical proton beams.

It was found that differences in proton fluence distributions are almost entirely due to differences in non-elastic nuclear interaction cross sections between the plastic materials and water, and it is not advisable to perform absorbed dose measurements nor to measure depth dose distributions in a plastic phantom in high-energy proton beams.

Fluence correction factors and stopping power ratios for clinical ion beams

For ions with small total range, dosimetry without applying FCF could in principle be performed in phantoms of materials other than water without a significant loss of accuracy, however, in clinical high-energy ion beams with penetration depths zw-eq ≥3 cm, absorbed dose measurements should be directly performed in water or accurate values of FCF need to be established.

The basic study of a bi-material range compensator for improving dose uniformity for proton therapy

The dose uniformity has been significantly improved in the target region by the use of the bi-material RC and the improvement has been obtained at the expense of blurring lateral penumbra.

Water equivalence of some plastic-water phantom materials for clinical proton beam dosimetry.

  • L. Al-SulaitiD. Shipley H. Palmans
  • Medicine, Physics
    Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine
  • 2012

Relationship between electron density and effective densities of body tissues for stopping, scattering, and nuclear interactions of proton and ion beams.

The present conversion functions are invariant and may be incorporated in treatment planning systems with a common function relating CT number to electron density, which will enable improved beam dose calculation while minimizing initial setup and quality management of the user's specific system.

Ridge filter design and optimization for the broad-beam three-dimensional irradiation system for heavy-ion radiotherapy.

The ridge filter design that produces a Gaussian-shaped spectrum of the particle ranges was found to be more robust to small errors and uncertainties in the beam application and optimized biological dose distributions show that a very good homogeneity is achievable in the target.

Biophysical characteristics of HIMAC clinical irradiation system for heavy-ion radiation therapy.

Biological dose calculation with Monte Carlo physics simulation for heavy-ion radiotherapy

This study demonstrates that the Monte Carlo physics simulation technique can be applied to improve the accuracy of the biological dose distribution in treatment planning of heavy-ion radiotherapy.