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Range Verification Methods in Particle Therapy: Underlying Physics and Monte Carlo Modeling.

Kraan AC - Front Oncol (2015)

Bottom Line: Currently, uncertainties in particle range lead to the employment of safety margins, at the expense of treatment quality.We include research studies and clinically applied methods.For each of the techniques, we point out advantages and disadvantages, as well as clinical challenges still to be addressed, focusing on MC simulation aspects.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Institute for Nuclear Physics (INFN), University of Pisa , Pisa , Italy.

ABSTRACT
Hadron therapy allows for highly conformal dose distributions and better sparing of organs-at-risk, thanks to the characteristic dose deposition as function of depth. However, the quality of hadron therapy treatments is closely connected with the ability to predict and achieve a given beam range in the patient. Currently, uncertainties in particle range lead to the employment of safety margins, at the expense of treatment quality. Much research in particle therapy is therefore aimed at developing methods to verify the particle range in patients. Non-invasive in vivo monitoring of the particle range can be performed by detecting secondary radiation, emitted from the patient as a result of nuclear interactions of charged hadrons with tissue, including β (+) emitters, prompt photons, and charged fragments. The correctness of the dose delivery can be verified by comparing measured and pre-calculated distributions of the secondary particles. The reliability of Monte Carlo (MC) predictions is a key issue. Correctly modeling the production of secondaries is a non-trivial task, because it involves nuclear physics interactions at energies, where no rigorous theories exist to describe them. The goal of this review is to provide a comprehensive overview of various aspects in modeling the physics processes for range verification with secondary particles produced in proton, carbon, and heavier ion irradiation. We discuss electromagnetic and nuclear interactions of charged hadrons in matter, which is followed by a summary of some widely used MC codes in hadron therapy. Then, we describe selected examples of how these codes have been validated and used in three range verification techniques: PET, prompt gamma, and charged particle detection. We include research studies and clinically applied methods. For each of the techniques, we point out advantages and disadvantages, as well as clinical challenges still to be addressed, focusing on MC simulation aspects.

No MeSH data available.


Stopping power (dE/dx), in MeV cm2 g−1, for protons in water as function of kinetic energy. The total, electronic, and nuclear stopping power are shown, as well as the characteristic regions. Made using NIST data (18).
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Figure 1: Stopping power (dE/dx), in MeV cm2 g−1, for protons in water as function of kinetic energy. The total, electronic, and nuclear stopping power are shown, as well as the characteristic regions. Made using NIST data (18).

Mentions: The electronic stopping power as function of the kinetic energy of protons impinging on a water target is shown in Figure 1, where the various regions mentioned above are indicated. Also indicated is the nuclear stopping power resulting from Coulomb interactions of the incident particles with the atomic nuclei, which is seen to contribute very little to the total stopping power. In Figure 2, the energy loss as function of depth is given for protons (left) and 12C ions (right) for various energies. The growing energy loss with decreasing particle velocity described by the Bethe-Bloch formula causes the characteristic Bragg peak.


Range Verification Methods in Particle Therapy: Underlying Physics and Monte Carlo Modeling.

Kraan AC - Front Oncol (2015)

Stopping power (dE/dx), in MeV cm2 g−1, for protons in water as function of kinetic energy. The total, electronic, and nuclear stopping power are shown, as well as the characteristic regions. Made using NIST data (18).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493660&req=5

Figure 1: Stopping power (dE/dx), in MeV cm2 g−1, for protons in water as function of kinetic energy. The total, electronic, and nuclear stopping power are shown, as well as the characteristic regions. Made using NIST data (18).
Mentions: The electronic stopping power as function of the kinetic energy of protons impinging on a water target is shown in Figure 1, where the various regions mentioned above are indicated. Also indicated is the nuclear stopping power resulting from Coulomb interactions of the incident particles with the atomic nuclei, which is seen to contribute very little to the total stopping power. In Figure 2, the energy loss as function of depth is given for protons (left) and 12C ions (right) for various energies. The growing energy loss with decreasing particle velocity described by the Bethe-Bloch formula causes the characteristic Bragg peak.

Bottom Line: Currently, uncertainties in particle range lead to the employment of safety margins, at the expense of treatment quality.We include research studies and clinically applied methods.For each of the techniques, we point out advantages and disadvantages, as well as clinical challenges still to be addressed, focusing on MC simulation aspects.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, National Institute for Nuclear Physics (INFN), University of Pisa , Pisa , Italy.

ABSTRACT
Hadron therapy allows for highly conformal dose distributions and better sparing of organs-at-risk, thanks to the characteristic dose deposition as function of depth. However, the quality of hadron therapy treatments is closely connected with the ability to predict and achieve a given beam range in the patient. Currently, uncertainties in particle range lead to the employment of safety margins, at the expense of treatment quality. Much research in particle therapy is therefore aimed at developing methods to verify the particle range in patients. Non-invasive in vivo monitoring of the particle range can be performed by detecting secondary radiation, emitted from the patient as a result of nuclear interactions of charged hadrons with tissue, including β (+) emitters, prompt photons, and charged fragments. The correctness of the dose delivery can be verified by comparing measured and pre-calculated distributions of the secondary particles. The reliability of Monte Carlo (MC) predictions is a key issue. Correctly modeling the production of secondaries is a non-trivial task, because it involves nuclear physics interactions at energies, where no rigorous theories exist to describe them. The goal of this review is to provide a comprehensive overview of various aspects in modeling the physics processes for range verification with secondary particles produced in proton, carbon, and heavier ion irradiation. We discuss electromagnetic and nuclear interactions of charged hadrons in matter, which is followed by a summary of some widely used MC codes in hadron therapy. Then, we describe selected examples of how these codes have been validated and used in three range verification techniques: PET, prompt gamma, and charged particle detection. We include research studies and clinically applied methods. For each of the techniques, we point out advantages and disadvantages, as well as clinical challenges still to be addressed, focusing on MC simulation aspects.

No MeSH data available.