Assessment of secondary neutrons in particle therapy by Monte Carlo simulations

2021 ◽  
Author(s):  
José Vedelago ◽  
Federico A Geser ◽  
Iván D Muñoz ◽  
Alberto Stabilini ◽  
Eduardo G Yukihara ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Angular Distribution ◽  
Monte Carlo Simulations ◽  
Radiation Transport ◽  
Heavy Ion ◽  
High Energy ◽  
Particle Therapy ◽  
Carbon Ions ◽  
Secondary Neutron ◽  
Secondary Neutrons

Abstract Objective: The purpose of this study is to estimate the energy and angular distribution of secondary neutrons inside a phantom in hadron therapy, which will support decisions on detector choice and experimental setup design for in-phantom secondary neutron measurements. Approach: Dedicated Monte Carlo simulations were implemented, considering clinically relevant energies of protons, helium and carbon ions. Since scored quantities can vary from different radiation transport models, the codes FLUKA, TOPAS and MCNP were used. The geometry of an active scanning beam delivery system for heavy ion treatment was implemented, and simulations of pristine and spread-out Bragg peaks were carried out. Previous studies, focused on specific ion types or single energies, are qualitatively in agreement with the obtained results. Main results: The secondary neutrons energy distributions present a continuous spectrum with two peaks, one centred on the thermal/epithermal region, and one on the high-energy region, with the most probable energy ranging from 19 MeV up to 240 MeV, depending on the ion type and its initial energy. The simulations show that the secondary neutron energies may exceed 400 MeV and, therefore, suitable neutron detectors for this energy range shall be needed. Additionally, the angular distribution of the low energy neutrons is quite isotropic, whereas the fast/relativistic neutrons are mainly scattered in the down-stream direction. Significance: It would be possible to minimize the influence of the heavy ions when measuring the neutron-generated recoil protons by selecting appropriate measurement positions within the phantom. Although there are discrepancies among the three Monte Carlo codes, the results agree qualitatively and in order of magnitude, being sufficient to support further investigations with the ultimate goal of mapping the secondary neutron doses both in- and out-of-field in hadrontherapy. The obtained secondary neutron spectra are available as supplementary material.

scholarly journals Measurement of the energy spectrum of secondary neutrons in a proton therapy environment

2017 ◽  
Vol 3 (2) ◽  
pp. 83-86
Author(s):  
Martin Dommert ◽  
Marcel Reginatto ◽  
Miroslav Zboril ◽  
Fine Fiedler ◽  
Stephan Helmbrecht ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Energy Spectrum ◽  
Monte Carlo Simulations ◽  
Proton Beam ◽  
Proton Therapy ◽  
Secondary Neutron ◽  
Incoming Proton ◽  
Secondary Neutrons ◽  
Proton Therapy Facility

AbstractMeasurement of the energy spectrum of secondary neutrons were carried out at the OncoRay Proton Therapy facility in Dresden, following an approach originating in neutron metrology which is well suited for both the characterization of secondary neutron fields at proton therapy facilities and the validation of Monte Carlo simulations. For the experiment, a brass target was placed in the proton beam and Bonner spheres measurements were made at a distance of 2 m from the target and at different angles, 15° to 120°, with respect to the incoming proton beam. The measured spectra were compared to Monte Carlo simulations.

scholarly journals Monte Carlo Simulations of Particle Acceleration at Oblique Shocks

1994 ◽  
Vol 142 ◽  
pp. 547-552
Author(s):  
Matthew G. Baring ◽  
Donald C. Ellison ◽  
Frank C. Jones
Keyword(s):  
Monte Carlo ◽  
Mach Number ◽  
Cosmic Rays ◽  
Monte Carlo Simulations ◽  
Cosmic Ray ◽  
Heavy Ion ◽  
High Energy ◽  
Shock Acceleration ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Acceleration

AbstractThe Fermi shock acceleration mechanism may be responsible for the production of high-energy cosmic rays in a wide variety of environments. Modeling of this phenomenon has largely focused on plane-parallel shocks, and one of the most promising techniques for its study is the Monte Carlo simulation of particle transport in shocked fluid flows. One of the principal problems in shock acceleration theory is the mechanism and efficiency of injection of particles from the thermal gas into the accelerated population. The Monte Carlo technique is ideally suited to addressing the injection problem directly, and previous applications of it to the quasi-parallel Earth bow shock led to very successful modeling of proton and heavy ion spectra, as well as other observed quantities. Recently this technique has been extended to oblique shock geometries, in which the upstream magnetic field makes a significant angle ΘB1 to the shock normal. In this paper, spectral results from test particle Monte Carlo simulations of cosmic-ray acceleration at oblique, nonrelativistic shocks are presented. The results show that low Mach number shocks have injection efficiencies that are relatively insensitive to (though not independent of) the shock obliquity, but that there is a dramatic drop in efficiency for shocks of Mach number 30 or more as the obliquity increases above 15°. Cosmic-ray distributions just upstream of the shock reveal prominent bumps at energies below the thermal peak; these disappear far upstream but might be observable features close to astrophysical shocks.Subject headings: acceleration of particles — cosmic rays — shock waves

In-Situ Measurement of Artificial Nuclides in Seabed Sediments Based on Monte Carlo Simulations and an Underwater HPGe Detector

2019 ◽  
Vol 53 (3) ◽  
pp. 16-22
Author(s):  
Jinzhao Zhang ◽  
Hongzhi Li ◽  
Xianguo Tuo
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Energy Resolution ◽  
Hpge Detector ◽  
High Energy ◽  
In Situ Measurement ◽  
Energy Calibration ◽  
High Energy Resolution ◽  
Seabed Sediments

AbstractIn-situ measurement of marine sediment radioactivity does not destroy the stratification of radionuclides in the sediment. We develop a novel seabed sediment radioactive measurement technique using a High Purity Germanium (HPGe) detector. The overall measurement system is designed, and the detector energy calibration is performed. The efficiency is calculated based on Monte Carlo simulations using the MCNP5 code. We compared the efficiency and energy resolution with the NaI(Tl) detection through experiments. NaI(Tl) detection is incapable of identifying the 137Cs artificial nuclides in seabed sediments due to the energy resolution limit. Hence, underwater HPGe detection is utilized due to its high energy resolution, which enables the detection of artificial nuclides 137Cs. The proposed method is of great significance in evaluating marine radioactive pollution.

scholarly journals Carbon Ion Radiobiology

Cancers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 3022 ◽  
Author(s):  
Walter Tinganelli ◽  
Marco Durante
Keyword(s):  
Normal Tissue ◽  
Biological Response ◽  
Metastatic Potential ◽  
Clinical Results ◽  
Heavy Ion ◽  
Particle Therapy ◽  
X Rays ◽  
Carbon Ions ◽  
Treatment Protocols ◽  
Target Region

Radiotherapy using accelerated charged particles is rapidly growing worldwide. About 85% of the cancer patients receiving particle therapy are irradiated with protons, which have physical advantages compared to X-rays but a similar biological response. In addition to the ballistic advantages, heavy ions present specific radiobiological features that can make them attractive for treating radioresistant, hypoxic tumors. An ideal heavy ion should have lower toxicity in the entrance channel (normal tissue) and be exquisitely effective in the target region (tumor). Carbon ions have been chosen because they represent the best combination in this direction. Normal tissue toxicities and second cancer risk are similar to those observed in conventional radiotherapy. In the target region, they have increased relative biological effectiveness and a reduced oxygen enhancement ratio compared to X-rays. Some radiobiological properties of densely ionizing carbon ions are so distinct from X-rays and protons that they can be considered as a different “drug” in oncology, and may elicit favorable responses such as an increased immune response and reduced angiogenesis and metastatic potential. The radiobiological properties of carbon ions should guide patient selection and treatment protocols to achieve optimal clinical results.

ASSESSMENT OF AMBIENT NEUTRON DOSE EQUIVALENT IN SPATIALLY FRACTIONATED RADIOTHERAPY WITH PROTONS USING PHYSICAL COLLIMATORS

2020 ◽  
Vol 189 (2) ◽  
pp. 190-197 ◽  
Author(s):  
Serdar Charyyev ◽  
C-K Chris Wang
Keyword(s):  
Monte Carlo ◽  
Neutron Dose ◽  
Monte Carlo Code ◽  
Dose Equivalent ◽  
Secondary Neutron ◽  
Fractionated Radiotherapy ◽  
Spot Scanning ◽  
Neutron Dose Equivalent ◽  
Secondary Neutrons ◽  
Proton Dose

Abstract New technique is trending in spatially fractionated radiotherapy with protons to utilize the spot scanning together with a physical collimator to obtain minibeams. The primary goal of this study is to quantify ambient neutron dose equivalent (${H}^{\ast }(10)$) due to the secondary neutrons when physical collimator is used to achieve desired minibeams. The ${H}^{\ast }(10)$ per treatment proton dose (D) was assessed using Monte Carlo code TOPAS and measured using WENDI-II detector at different angles (135, 180, 225 and 270 degrees) and distances (11 cm, 58 and 105 cm) from the phantom for two cases: with and without physical collimation. Without collimation $\frac{H^{\ast }(10)}{D}$ varied from 0.0013 to 0.242 mSv/Gy. With collimation $\frac{H^{\ast }(10)}{D}$ varied from 0.017 to 3.23 mSv/Gy. Results show that the secondary neutron dose will increase tenfold when the physical collimator is used. Regardless, it will be low and comparable to the neutron dose produced by conventional passive-scattered proton beams.

Sign in / Sign up

Export Citation Format

Share Document