ABSTRACT
@#<b>Objective</b> To analyze the distribution features of the Bragg peak of carbon ion beams in materials using SRIM software, and to explore the use of computed tomography (CT) number to calculate the incident energy of carbon ion beams. <b>Methods</b> SRIM software was used to study the travel of carbon ion beams (100 to 300 MeV/u) in different equivalent materials, and analyze the effects of the incident energy of carbon ion beams and the type and thickness of equivalent materials on the depth of the Bragg peak of carbon ion beams. Origin 2017 was used to analyze the functional relationship between CT number and water-equivalent Bragg peak depth ratio (<i>Di</i>) through data fitting. <b>Results</b> The ratios of the Bragg peak depths in equivalent materials to that in water almost stayed constant with the increase in the incident energy of carbon ion beams. Through the functional relation between CT number and <i>D</i><sub><i>i</i></sub>, the Bragg peak depth of a carbon ion beam of a given energy in an equivalent material could be converted to the equivalent Bragg peak depth in water. <b>Conclusion</b> With the water-equivalent Bragg peak depth ratio <i>D</i><sub><i>i</i></sub> and CT number of different volume units of human tissues, the equivalent Bragg peak depth in water required for the Bragg peak to fall in the tumor can be accurately calculated, which can be used to reversely infer the needed incident energy of carbon ion beams.
ABSTRACT
Objective:To analyze the influence of magnetic field on the proton beam delivery and dose distribution, and develop a correction method for the Bragg peak (BP) shift under the vertical magnetic field, providing reference for the dose calculation and beam delivery of MRI-guided proton therapy.Methods:Monte Carlo (MC) simulation was used to study the dose distribution of the proton beam in the water phantom under the magnetic field. The BP location was corrected by the method of" angle correction+ energy correction" , and the correction parameters were calculated by the analytical formula based on the simulation data.Results:The magnetic field caused the dose distortion and shift of BP location. The shift degree was increased with the increase of field strength and initial energy. Compared with MC simulation, the result of calculating proton deflection in the air by the analytical method yielded a deviation within 0.2%. Based on the simulation data and calculation formulas, the correction parameters under different conditions could be calculated within 1 s by using the MATLAB programming. The calculation results showed that the air layer with magnetic field, isocenter depth, irradiation direction exerted different influence on the correction parameters. After correction, the BP location was basically consistent with the expected (offset ≤0.2 mm).Conclusions:The BP shift under the vertical magnetic field can be effectively corrected by " the angle correction+ energy correction" method. The correction parameters under different conditions can be quickly and accurately calculated by the calculation formulas based on simulation data.
ABSTRACT
Objective To discuss the distribution characteristics of the Bragg peak in proton therapy using the SRIM code. Methods Based on the SRIM code, the transport processes of a high-energy proton beam injecting into different materials (H2O, C2H6O、C8H8、Al and Fe)with incident energies of 50 MeV～250 MeV have been simulated and analyzed. And the relationship between the incident energies, different materials and thickness, and the depth of the Bragg peak was also discussed when the protons injected into different materials and compared with the simulation results of professional Monte Carlo code, such as Fluka 2011 and MCNPX. Results The simulation results indicate that the depths of the Bragg peak increase gradually and the peaks broaden with the increase of incident proton energies for different materials; The ratio of the depth of the Bragg peak in different materials to that in water under the same incident energy changes little and is approximately a constant which doesn’t depend on the proton incident energy. A good consistency was found between the results and those obtained using Fluka and MCNPX programs. Conclusion The simulation accuracy of the SRIM on the proton beam transport is acceptable, and is suitable for the beginning learners.
ABSTRACT
Protons and heavy ion radiation therapy have proven highly effective against a wide range of cancers and in recent decades there have been rapid advances.Due to the physical characteristics of the Bragg-peak and superior biological properties,proton and heavy ion radiation is able to focus its energy on the tumor while minimizing exposure to surrounding normal tissues and organs,which is expected help enhance the tumor dose and reduce normal tissue damage.In recent years,many studies have explored the efficacy and safety of proton and heavy ion radiotherapy on various malignancies,such as head and neck cancer,lung cancer,esophageal cancer,and liver cancer.The results of these studies enable a better understanding of the characteristics and advantages of proton and heavy ion therapy.
ABSTRACT
Proton is quite different from x-ray in terms of energy emission. As it enters a cancer patient's body through skin and tissue, it releases a relatively low dose of energy before it reaches the target. It, however, hits the targeted tumor by depositing the biggest dose of energy on it, then suddenly stopping its activity afterwards. The point where the highest energy is released is called as the Bragg peak. The proton beam has many advantages over the conventional x-ray beam because the proton beam radiates primarily the tumor site, leaving the surrounding healthy tissue and organs totally unharmed or relatively less damaged. Thus, the patients can enjoy much more enhanced quality-of-life during and after the treatment as well as have a high probability to be cured from their diseases.
Subject(s)
Humans , Proton Therapy , Protons , SkinABSTRACT
As a new radiotherapy for carcinomas, Proton Therapy has been making progresses. Compared with conventional radiation, proton has a better physical characteristic and a similar biological effect. Proton Therapy consists of Conformal Proton Radiotherapy, Intensity-Modulated Proton Therapy, Stereotactic Radiotherapy, Proton Scanning Radiation and et al. With the utilization of Bragg peak, Proton therapy can increase the dose of carcinoma region and reduce the dose of normal tissue, and thus it has a good curative effect and can be a good cure for many indications. In spite of the above-mentioned, Proton therapy has to be improved in the future.