Proton Beam Energy Research Articles

Model-Free Parametrization of Cross Sections for Cumulative Pion Production on Nuclei in Terms of Stavinsky’s Scale Variable x

A model-free parametrization of invariant differential cross sections for cumulative pion production on nuclei ofmass number in the range of A = 2–210 in the backward hemisphere is obtained in the representation of Stavinsky’s scale variable x on the basis of cross sections available in the literature that were measured for several nuclei and several values of the angle θ at proton-beam energies in the range of E0 = 9–10 GeV. The use of this parametrization in its applicability region makes it possible to calculate pion-production cross sections in the range of x = 0.25–3.5 to an acceptable degree of precision.

GEOMETRICAL EFFICIENCY OF PLANE-PARALLEL IONIZATION CHAMBERS IN PROTON SCANNING BEAM

For commissioning of a proton therapy unit depth dose distributions must be determined and introduced into the Treatment Planning System. In pencil beam scanning (PBS) technique, integral depth dose (IDD) acquisition should be performed with detector large enough to ensure entire beam laterally broadened by scattered and secondary contributions. The purpose of this article is to quantify, using measurements and Monte Carlo transport calculations, the ionization chamber's (IC) geometrical efficiency versus the chamber radius and proton beam energy. The geometrical efficiency of 0.99 was determined for energies up to 160 and 190 MeV for 4.08 and 6 cm radius IC. Much lower geometrical efficiency was obtained for the energy of 226.08 MeV and results in charge loss of 5.8 and 3.6%, respectively. Relative IDD differences between IC 4.08 and 6 cm in radius increase with proton energy and reach 2.4% at the mid-range depth for 226.08 MeV.

Abstract ID: 173 Geant4-based Monte Carlo simulations of a transport beam line for multidisciplinary applications of laser-driven proton beams

The ELIMED (MEDical and multidisciplinary application at ELI-Beamlines) beamline is being developed with the aim of transport and select in energy proton and ion beams accelerated by laser-matter interaction at ELI-Beamlines (Extreme Light Infrastructure) user facility in the Czech Republic [1] . The beamline will be a key part of the ELIMAIA (ELI Multidisciplinary Application of laser-Ion Acceleration) user beamline, where experiments will be carried out with the purpose of investigating the feasibility of using laser-driven beams for multidisciplinary applications, including medical ones [2] . A Monte Carlo simulation of the ELIMED beamline has been developed for the following purposes: to support the design of the beamline in terms of particle transport efficiency, to optimize the beam parameters at the irradiation point in air and, finally, to predict the transport elements parameters to deliver dose distributions of possible clinical relevance [3] . The application has been developed with the Geant4 Monte Carlo toolkit. It has been designed in a modular way in order to easily switch on/off geometrical components according to different experimental setups. The application has been preliminary validated comparing particle tracks to results obtained with reference codes for transport of particles in magnetic fields, with a good agreement. Specifically, energy distributions, lateral beam profiles and longitudinal dose distributions in the in-air final section were simulated for proton beams with energies ranging between 5 and 60 MeV. A transmission efficiency of more than 10% was calculated at 60 MeV, which implies the delivery of up to tens of cGy per pulse at the sample irradiation point. Assuming a repetition rate of 1 Hz, between 1 and 10 Gy/min can be potentially achieved in such conditions. These results are of great importance to assess the possibility of carrying out in vitro and in vivo radiobiology experiments aiming to demonstrate the possible future use of optically accelerated beams for therapeutic purposes.

Abstract ID: 164 Detector MC study for measurement of nuclear reaction cross section relevant in particle therapy

In protontherapy proton beams are used to treat deep-seated tumors, exploiting the charged particles characteristic depth-dose deposition profile. In clinical practice a constant RBE equal to 1.1 is adopted, regardless of the demonstrated RBE variations [1] , which depends on physical and biological parameters. Among other mechanisms, also nuclear interactions might influence the proton RBE due to secondary heavier particles produced by target fragmentation that can significantly contribute to the total dose. Nuclear interactions especially affect the dose delivered in the entry channel, corresponding to healthy tissues preceding the tumor region [2] . As a consequence, an unwanted and undetermined increase of normal tissues complications probability (NTCP) may occur. At present, experimental data on target fragmentation are scarce. In fact, at therapeutic proton beam energy, fragments identification would be difficult due to their low energy and short range. The main goal of the FOOT (FragmentatiOn Of Target) experiment of INFN is to measure fragment production cross sections, to improve the proton radiobiological characterization, the NTCP control and also the nuclear models adopted By Monte Carlo codes. Target ( 16 O and 12 C nuclei) fragmentation induced by 150–250 AMeV proton beams will be studied via an inverse kinematic strategy: 16 O and 12 C beams impinge on hydrocarbon and graphite targets to provide, by subtraction, fragmentation cross sections on hydrogen. A dedicated experimental setup is currently being developed and optimized. A magnetic spectrometer, a Δ E detector with TOF capabilities and a calorimeter will be used to measure the fragments momenta, Δ E, TOF and kinetic energy. In this work we will present the results of a Monte Carlo study, based on the FLUKA code [3] , which aims to evaluate the detector performance and the expected resolution on fragment identification and on the nuclear cross sections relevant for charged particle therapy. We shall also present a preliminary study of the expected predicted differential cross sections for the production of different fragments on the basis of the physics models of FLUKA.

Exploring CP-even scalars of a Two Higgs-doublet model in future e− p colliders

In this proceeding we shall explore the potential of a future e− p collider to probe the CP-even scalars in a two Higgs doublet model. We consider Type-I in this study. The mass of the lighter scalar particle is considered to be the Higgs-boson, mh = 125 GeV, and a heavy scalar mH = 270 GeV. The centre of mass energy for the e− p collision is considered as in the Large Hadron Electron Collider and the Future Circular Hadron Electron Collider configurations, by fixing the proton beam energy to be Ep = 7 and 50 TeV, respectively, and an electron beam energy of Ee = 60 GeV. Production cross sections of these scalars are also shown at higher electron beam energies. Future prospects of these studies are also discussed.

The optimal balance between quality and efficiency in proton radiography imaging technique at various proton beam energies: A Monte Carlo study

Proton radiography is a novel imaging modality that allows direct measurement of the proton energy loss in various tissues. Currently, due to the conversion of so-called Hounsfield units from X-ray Computed Tomography (CT) into relative proton stopping powers (RPSP), the uncertainties of RPSP are 3–5% or higher, which need to be minimized down to 1% to make the proton treatment plans more accurate.In this work, we simulated a proton radiography system, with position-sensitive detectors (PSDs) and a residual energy detector (RED). The simulations were built using Geant4, a Monte Carlo simulation toolkit. A phantom, consisting of several materials was placed between the PSDs of various Water Equivalent Thicknesses (WET), corresponding to an ideal detector, a gaseous detector, silicon and plastic scintillator detectors. The energy loss radiograph and the scattering angle distributions of the protons were studied for proton beam energies of 150MeV, 190MeV and 230MeV. To improve the image quality deteriorated by the multiple Coulomb scattering (MCS), protons with small angles were selected. Two ways of calculating a scattering angle were considered using the proton’s direction and position.A scattering angle cut of 8.7mrad was applied giving an optimal balance between quality and efficiency of the radiographic image. For the three proton beam energies, the number of protons used in image reconstruction with the direction method was half the number of protons kept using the position method.

Ranges of protons in biological targets

Abstract The paper introduces a simple fitting function for quick assessment of proton ranges in biological targets and human tissues. The function has been found by fitting an extensive data set of Monte Carlo proton ranges obtained with the aid of the SRIM-2013 code. The data has been collected for 28 different targets at 8 energies in the interval from 60 MeV to 220 MeV. The paper shows that at a given kinetic proton-beam energy, the Monte Carlo ranges can be satisfactorily fitted by a power function that depends solely on the target density. This is a great advantage for targets, for which the exact chemical composition is not known, or the mean ionizing potential is not reliably known. The satisfactory fit is meant as the fit that stays within the natural range straggling of the Monte Carlo ranges. In the second step, the energy-scaling yielding a universal fitting formula for proton ranges as a function of proton-beam energy and target density is introduced and discussed.

Reactive oxygen species-based measurement of the dependence of the Coulomb nanoradiator effect on proton energy and atomic Z value

Purpose: The Coulomb nanoradiator (CNR) effect produces the dose enhancement effects from high-Z nanoparticles under irradiation with a high-energy ion beam. To gain insight into the radiation dose and biological significance of the CNR effect, the enhancement of reactive oxygen species (ROS) production from iron oxide or gold NPs (IONs or AuNPs, respectively) in water was investigated using traversing proton beams.Methods and materials: The dependence of nanoradiator-enhanced ROS production on the atomic Z value and proton energy was investigated. Two biologically important ROS species were measured using fluorescent probes specific to •OH or in a series of water phantoms containing either AuNPs or IONs under irradiation with a 45- or 100-MeV proton beam.Results: The enhanced generation of hydroxyl radicals (•OH) and superoxide anions () was determined to be caused by the dependence on the NP concentration and proton energy. The proton-induced Au or iron oxide nanoradiators exhibited different ROS enhancement rates depending on the proton energy, suggesting that the CNR radiation varied. The curve of the superoxide anion production from the Au-nanoradiator showed strong non-linearity, unlike the linear behavior observed for hydroxyl radical production and the X-ray photoelectric nanoradiator. In addition, the 45-MeV proton-induced Au nanoradiator exhibited an ROS enhancement ratio of 8.54/1.50 ( / •OH), similar to that of the 100-KeV X-ray photoelectric Au nanoradiator (7.68/1.46).Conclusions: The ROS-based detection of the CNR effect revealed its dependence on the proton beam energy, dose and atomic Z value and provided insight into the low-linear energy transfer (LET) CNR radiation, suggesting that these factors may influence the therapeutic efficacy via chemical reactivities, transport behaviors, and intracellular oxidative stress.

Simulations and measurements of proton beam energy spectrum after energy degradation

At the proton therapy facility PROSCAN of the Paul Scherrer Institute the energy modulation of the cyclotron generated proton beam is performed via material insertion into the beam trajectory. The energy spectrum of the particles propagating forwards after such procedure has been simulated and measured. The current paper summarizes the results of these simulations and measurements and illustrates their significance for the future developments of a gantry for proton therapy at the Paul Scherrer Institute.

Measurement of activation cross sections of the 27Al(n,α)24Na and 27Al(n,p)27Mg reactions with quasi-monoenergetic neutrons

Abstract The cross sections of the 27Al(n,α)24Na and 27Al(n,p)27Mg reactions with the average neutron energies of 15.2, 26.4, and 37.2 MeV were measured using the activation and off-line γ−ray spectrometric technique at the Korean Institute of Radiological and Medical Sciences (KIRAMS), Korea. Quasi-monoenergetic neutrons produced via the 9Be(p,n) reaction with the proton beam energies of 25, 35, and 45 MeV from the MC50 cyclotron of KIRAMS were used. The present measured values were compared with those from the evaluated nuclear data libraries ENDF/B-VII, TENDL-2015, TALYS 1.8, and from literature. In general, a close agreement with the literature data as well as the evaluated data was found.

Measuring CP nature of top-Higgs couplings at the future Large Hadron electron Collider

We investigate the sensitivity of top-Higgs coupling by considering the associated vertex as CP phase (ζt) dependent through the process pe−→t¯hνe in the future Large Hadron electron Collider. In particular the decay modes are taken to be h→bb¯ and t¯ → leptonic mode. Several distinct ζt dependent features are demonstrated by considering observables like cross sections, top-quark polarisation, rapidity difference between h and t¯ and different angular asymmetries. Luminosity (L) dependent exclusion limits are obtained for ζt by considering significance based on fiducial cross sections at different σ-levels. For electron and proton beam-energies of 60 GeV and 7 TeV respectively, at L=100 fb−1, the regions above π/5<ζt≤π are excluded at 2σ confidence level, which reflects better sensitivity expected at the Large Hadron Collider. With appropriate error fitting methodology we find that the accuracy of SM top-Higgs coupling could be measured to be κ=1.00±0.17(0.08) at s=1.3(1.8) TeV for an ultimate L=1ab−1.

Systematic out-of-field secondary neutron spectrometry and dosimetry in pencil beam scanning proton therapy.

Systematic investigation of the energy and angular dependence of secondary neutron fluence energy distributions and ambient dose equivalents values (H*(10)) inside a pencil beam scanning proton therapy treatment room using a gantry. Neutron fluence energy distributions were measured with an extended-range Bonner sphere spectrometer featuring ³He proportional counters, at four positions at 0°, 45°, 90°, and 135° with respect to beam direction and at a distance of 2 m from the isocenter. The energy distribution of secondary neutrons was investigated for initial proton beam energies of 75 MeV, 140 MeV, and 200 MeV, respectively, using a 2D scanned irradiation field of 11 × 11 cm² delivered to a 30 × 30 × 30 cm³ PMMA phantom. Additional measurements were performed at a proton energy of 118 MeV including a 5 cm range-shifter (PMMA), yielding a Bragg peak position similar to that of 75 MeV protons. Ambient dose equivalent values from 0.3 μSv/Gy (75 MeV; 90°) to 24 μSv/Gy (200 MeV; 0°) were measured inside the treatment room at a distance of 2 m from the isocenter. H*(10) values were lower (by factors of up to 7.2 (at 45°)) at 75 MeV compared to those at 118 MeV with the 5 cm range-shifter. At 0° and 45°, an evaporation peak was found in the measured neutron fluence energy distributions, at neutron energies around MeV, which contributes about 50% to total H*(10) values, for all investigated proton beam energies. This study showed a pronounced increase of secondary neutron H*(10) values inside the proton treatment room with increasing proton energy without beam modifiers. For example, in beam direction this increase was about a factor of 50 when protons of 75 MeV and 200 MeV were compared. The existence of a peak of secondary neutrons in the MeV region was demonstrated in beam direction (0°). This peak is due to evaporation neutrons produced in the existing surrounding materials such as those used for the gantry. Therefore, any simulation of the secondary neutrons within a proton treatment room must take these materials into account. In addition, the results obtained here show that the use of a range-shifter increases the production of secondary neutrons inside the treatment room. Using a range-shifter, the higher neutron doses observed mainly result from the higher incident proton energy (118 MeV instead of 75 MeV when no range-shifter was used), due to higher neutron production cross-sections.

PIXE detection limit for aluminium thin film deposited on Si-based matrix

The aim of this work is to show the capability of the PIXE technique as a rapid, non-destructive and accurate quantification method on silicon (Si) and in Si-based matrix. For this purpose, an aluminium (Al) thin film (2.5nm) deposition on silicon and silicon carbide substrates was carried out using effect joule evaporation. In order to improve the sensitivity for Al determination, a systematic study was undertaken using proton ion beam at different energies (from 0.2 to 3MeV) with a different incident angles (0°, 60°, and 80°). Proton beam energy of 0.3MeV and 80° tilting angle permits a more accurate determination of Al/Si with high sensitivity within few minutes of acquisition time and with a LOD less than 1.2×1015at/cm2. However, the LOD of Al decreases by one order of magnitude when SiC substrate is used instead of Si. Hence, these optimal parameters were used to determine the concentration of Al doping in thin homoepitaxial SiC layer. It was found that the Al/Si ratio was varied from 0.066 to 0.36 when the incident angle varied from 0 to 80°.

Number distribution of emitted electrons by MeV H+ impact on carbon

The statistical distributions of the number of the forward- and backward-emitted secondary electrons (SE’s) from a thin carbon foil have been measured in coincidence with foil-transmitted H+ ions of 0.5–3.0MeV in every 0.5MeV step. The measured SE energy spectra were fitted by assuming a Pólya distribution for the simultaneous n-SE emission probabilities. For our previous data with a couple of the carbon foils with different thicknesses, a similar analysis has been carried out. As a result, it was found that the measured spectra could be reproduced as well as by an analysis without placing any restriction on the emission probabilities both for the forward and backward SE emission. The obtained b-parameter of the Pólya distribution, which is a measure of the deviation from a Poisson distribution due to the cascade multiplication by high energy internal SE’s, increases monotonically with the incident energy of proton beams. On the other hand, a clear foil-thickness dependence is not observed for the b-parameter. A theoretical model which could reproduced the magnitude of the b-parameter for the SE energy spectra obtained with thick Au, Cu and Al targets is found to overestimates our values for thin carbon foils significantly. Another model calculation is found to reproduce our b-values very well.

Systematic Study of Three-Nucleon System Dynamics in Deuteron–Proton Breakup Reaction

We report on preliminary results of the first measurement of elastic scattering of protons from deuterons and proton induced deuteron breakup at proton beam energy of 108 MeV conducted at new Cyclotron Center Bronowice IFJ PAN in Krakow. The experiment is aimed at precise determination of the differential cross section for extensive set of kinematical configurations in a wide range of angular acceptance. In the first data taking run the average statistical per-point accuracy of about 5% has been reached.

Prediction and compensation of magnetic beam deflection in MR-integrated proton therapy: a method optimized regarding accuracy, versatility and speed

The integration of magnetic resonance imaging (MRI) and proton therapy for on-line image-guidance is expected to reduce dose delivery uncertainties during treatment. Yet, the proton beam experiences a Lorentz force induced deflection inside the magnetic field of the MRI scanner, and several methods have been proposed to quantify this effect. We analyze their structural differences and compare results of both analytical and Monte Carlo models. We find that existing analytical models are limited in accuracy and applicability due to critical approximations, especially including the assumption of a uniform magnetic field. As Monte Carlo simulations are too time-consuming for routine treatment planning and on-line plan adaption, we introduce a new method to quantify and correct for the beam deflection, which is optimized regarding accuracy, versatility and speed. We use it to predict the trajectory of a mono-energetic proton beam of energy E0 traversing a water phantom behind an air gap within an omnipresent uniform transverse magnetic flux density B0. The magnetic field induced dislocation of the Bragg peak is calculated as function of E0 and B0 and compared to results obtained with existing analytical and Monte Carlo methods. The deviation from the Bragg peak position predicted by Monte Carlo simulations is smaller for the new model than for the analytical models by up to 2 cm. The model is faster than Monte Carlo methods, less assumptive than the analytical models and applicable to realistic magnetic fields. To compensate for the predicted Bragg peak dislocation, a numerical optimization strategy is introduced and evaluated. It includes an adjustment of both the proton beam entrance angle and energy of up to 25° and 5 MeV, depending on E0 and B0. This strategy is shown to effectively reposition the Bragg peak to its intended location in the presence of a magnetic field.

Measurement of stray neutron doses inside the treatment room from a proton pencil beam scanning system

PurposeTo measure the environmental doses from stray neutrons in the vicinity of a solid slab phantom as a function of beam energy, field size and modulation width, using the proton pencil beam scanning (PBS) technique. MethodMeasurements were carried out using two extended range WENDI-II rem-counters and three tissue equivalent proportional counters. Detectors were suitably placed at different distances around the RW3 slab phantom. Beam irradiation parameters were varied to cover the clinical ranges of proton beam energies (100–220MeV), field sizes ((2×2)–(20×20)cm2) and modulation widths (0–15cm). ResultsFor pristine proton peak irradiations, large variations of neutron H∗(10)/D were observed with changes in beam energy and field size, while these were less dependent on modulation widths. H∗(10)/D for pristine proton pencil beams varied between 0.04μSvGy−1 at beam energy 100MeV and a (2×2)cm2 field at 2.25m distance and 90° angle with respect to the beam axis, and 72.3μSvGy−1 at beam energy 200MeV and a (20×20) cm2 field at 1m distance along the beam axis. ConclusionsThe obtained results will be useful in benchmarking Monte Carlo calculations of proton radiotherapy in PBS mode and in estimating the exposure to stray radiation of the patient. Such estimates may be facilitated by the obtained best-fitted simple analytical formulae relating the stray neutron doses at points of interest with beam irradiation parameters.

Monte Carlo characterisation of the Dose Magnifying Glass for proton therapy quality assurance

A Geant4 Monte Carlo simulation study was carried out to characterise a novel silicon strip detector, the Dose Magnifying Glass (DMG), for use in proton therapy Quality Assurance. We investigated the possibility to use DMG to determine the energy of the incident proton beam. The advantages of DMG are quick response, easy operation and high spatial resolution. In this work we theoretically proved that DMG can be used for QA in the determination of the energy of the incident proton beam, for ocular and prostate cancer therapy. The study was performed by means of Monte Carlo simulations Experimental measurements are currently on their way to confirm the results of this simulation study.

New cross sections for the27Al(p,x)7Be nuclear process: Monitoring proton beam energy via the22Na/7Be cross-section ratio between 45 and 200 MeV

Cross sections are presented for 7 Be produced in the proton bombardment of natural Al up to 200 MeV and compared with previous literature data. Cross-section ratios for the 27 Al(p,x) 22 Na and 27 Al(p,x) 7 Be nuclear processes are also presented in the energy region 45−200 MeV, exploiting our previously reported cross sections for the 27 Al(p,x) 22 Na process. The applicability for energy monitoring of proton beams by exploiting the 22 Na/ 7 Be cross-section ratio is discussed. Monte Carlo simulations in a simplified geometry provide additional information on activation of an Al monitor foil by secondary neutrons, indicating greater sensitivity to these neutrons by 24 Na as a beam monitor than 22 Na and 7 Be.

Measurements of cross sections for the 209Bi(n, 4n) reaction by using high energy neutrons with continuous energy spectra

We measured 209 Bi(n, 4n) cross sections at neutron energies E n = 29.8 ± 1.8 MeV and E n = 34.8 ± 1.8 MeV. Bismuth oxide samples were irradiated with the neutrons produced by impinging 30, 35 and 40 MeV proton beams on a 1.05 cm thick beryllium target, where the proton beams were from the MC-50 Cyclotron of Korea Institute of Radiological Medical Sciences (KIRAMS). The neutron flux for each proton beam energy E p , Φ E p ( E n ), has a broad spectrum with respect to E n . By taking the difference in the neutron fluxes, the difference spectra, Φ 40 ( E n ) −Φ 35 ( E n ) and Φ 35 ( E n ) −Φ 30 ( E n ), are obatined and found to be peaked at E n = 29.8 and 34.8 MeV, respectively, with a width of about 3.6 MeV. By making use of this observation and employing the TENDL-2009 library we could extract the 209 Bi(n, 4n) 206 Bi cross sections at the aforementioned neutron energies.