Creating a spread-out Bragg peak in proton beams

Jette, David; Chen, Weimin

doi:10.1088/0031-9155/56/11/n01

Cited by 69 publications

(44 citation statements)

References 13 publications

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“…Although the physical dose distribution of protons, represented by the Bragg peak, offers the potential to minimize adverse effects on normal tissue, the narrow dose deposition of protons is a challenge for proton therapy for targets of sufficient depth or volume. A 'spread out Bragg peak' can be accomplished with a scanning proton beam or a series of repeated fields with different proton energies, allowing for dose deposition along a greater depth of tissue while sparing surrounding normal tissues [59,60].…”

Section: Energy Distributionmentioning

confidence: 99%

Teletherapy: Advanced Techniques

Stockham

Balagamwala

Singh

et al. 2013

Ophthalmic Radiation Therapy

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Radiotherapy has been utilized as a treatment for ophthalmologic processes for more than one hundred years. Over this century, the field of ophthalmologic oncology has been revolutionized through medical discoveries, development of novel surgical interventions, and innovation of advanced radiotherapy techniques. In this chapter, novel radiotherapy techniques are considered. Material presented will build on basic radiation therapy principles, techniques, and treatment parameters established in the previous chapter through consideration of intensity modulated radiotherapy, stereotactic radiotherapy, and heavy ion therapy. Deliberation of matters common across advanced radiotherapy techniques including target delineation, treatment planning, and requisites for ensuring accurate, precise treatment delivery will precede discussion of advanced radiotherapy techniques as applied to the management ophthalmologic malignancies.

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Section: Energy Distributionmentioning

confidence: 99%

Teletherapy: Advanced Techniques

Stockham

Balagamwala

Singh

et al. 2013

Ophthalmic Radiation Therapy

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“…In many previous studies [16–20], an analytical method was adopted to rapidly generate the Bragg curves and then the optimization procedure was performed to generate a dose SOBP. Although the analytical method has advantages in the calculation speed, systematic uncertainties exist owing to the approximated expression of Bragg peaks in the dose calculations.…”

Section: Introductionmentioning

confidence: 99%

Physical parameter optimization scheme for radiobiological studies of charged particle therapy

et al. 2018

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We have developed an easy-to-implement method to optimize the spatial distribution of a desired physical quantity for charged particle therapy. The basic methodology requires finding the optimal solutions for the weights of the constituent particle beams that together form the desired spatial distribution of the specified physical quantity, e.g., dose or dose-averaged linear energy transfer (LETd), within the target region. We selected proton, 4He ion, and 12C ion beams to demonstrate the feasibility and flexibility of our method. The pristine dose Bragg curves in water for all ion beams and the LETd for proton beams were generated from Geant4 Monte Carlo simulations. The optimization algorithms were implemented using the Python programming language. High-accuracy optimization results of the spatial distribution of the desired physical quantity were then obtained for different cases. The relative difference between the real value and the expected value of a given quantity was approximately within ± 1.0% in the whole target region. The optimization examples include a flat dose spread-out Bragg peak (SOBP) for the three selected ions, an upslope dose SOBP for protons, and a downslope dose SOBP for protons. The relative difference was approximately within ± 2.0% for the case with a flat LETd (target value = 4 keV/μm) distribution for protons. These one-dimensional optimization algorithms can be extended to two or three dimensions if the corresponding physical data are available. In addition, this physical quantity optimization strategy can be conveniently extended to encompass biological dose optimization if appropriate biophysical models are invoked.

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“…While most treatments use the passive scattering technique, newer centers are adopting the more advanced pencil‐beam scanning (PBS) technique, which reduces the out‐of‐the‐field dose and given sufficiently small spot size can also achieve better dose conformality. In passive scattering, the range of the proton beam is modulated to create the spread‐out Bragg peak (SOBP) 2 , 3 . Ridge filters or, more commonly, rotating modulator wheels, (4) are used to create treatment fields of variable modulation depths that can extend to the skin surface.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the range shifter model for proton pencil‐beam scanning for the Eclipse v.11 treatment planning system

Matysiak

Yeung

Slopsema

et al. 2016

J Applied Clin Med Phys

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Existing proton therapy pencil‐beam scanning (PBS) systems have limitations on the minimum range to which a patient can be treated. This limitation arises from practical considerations, such as beam current intensity, layer spacing, and delivery time. The range shifter (RS) — a slab of stopping material inserted between the nozzle and the patient — is used to reduce the residual range of the incident beam so that the treatment ranges can be extended to shallow depths. Accurate modeling of the RS allows one to calculate the beam spot size entering the patient, given the proton energy, for arbitrary positions and thicknesses of the RS in the beam path. The Eclipse version 11 (v11) treatment planning system (TPS) models RS‐induced beam widening by incorporating the scattering properties of the RS material into the V‐parameter. Monte Carlo simulations with Geant4 code and analytical calculations using the Fermi‐Eyges (FE) theory with Highland approximation of multiple Coulomb scattering (MCS) were employed to calculate proton beam widening due to scattering in the RS. We demonstrated that both methods achieved consistent results and could be used as a benchmark for evaluating the Eclipse V‐parameter model. In most cases, the V‐parameter model correctly predicted the beam spot size after traversing the RS. However, Eclipse did not enforce the constraint for a nonnegative covariance matrix when fitting the spot sizes to derive the phase space parameters, which resulted in incorrect calculations under specific conditions. In addition, Eclipse v11 incorrectly imposed limits on the individual values of the phase space parameters, which could lead to incorrect spot size values in the air calculated for beams with spot sigmas <3.8 mm. Notably, the TPS supplier (Varian) and hardware vendor (Ion Beam Applications) inconsistently refer to the RS position, which may result in improper spot size calculations.PACS number(s): 87.53.Jw, 87.53.Kn, 87.55.kd, 87.56.‐v

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Creating a spread-out Bragg peak in proton beams

Cited by 69 publications

References 13 publications

Teletherapy: Advanced Techniques

Teletherapy: Advanced Techniques

Physical parameter optimization scheme for radiobiological studies of charged particle therapy

Evaluation of the range shifter model for proton pencil‐beam scanning for the Eclipse v.11 treatment planning system

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