Purpose: In this study, the required dose rates for optimal treatment of tumoral tissues when using proton therapy in the treatment of defective tumours seen in mandibles has been calculated. We aimed to protect the surrounding soft and hard tissues from unnecessary radiation as well as to prevent complications of radiation. Bragg curves of therapeutic energized protons for two different mandible (molar and premolar) plate phantoms were computed and compared with similar calculations in the literature. The results were found to be within acceptable deviation values. Methods: In this study, mandibular tooth plate phantoms were modelled for the molar and premolar areas and then a Monte Carlo simulation was used to calculate the Bragg curve, lateral straggle/range and recoil values of protons remaining in the therapeutic energy ranges. The mass and atomic densities of all the jawbone layers were selected and the effect of layer type and thickness on the Bragg curve, lateral straggle/range and the recoil were investigated. As protons move through different layers of density, lateral straggle and increases in the range were observed. A range of energies was used for the treatment of tumours at different depths in the mandible phantom. Results: Simulations revealed that as the cortical bone thickness increased, Bragg peak position decreased between 0.47–3.3%. An increase in the number of layers results in a decrease in the Bragg peak position. Finally, as the proton energy increased, the amplitude of the second peak and its effect on Bragg peak position decreased. Conclusion: These findings should guide the selection of appropriate energy levels in the treatment of tumour structures without damaging surrounding tissues.

Heavy ions have varying effects on the target. The most important factor in comparing this effect is Linear Energy Transfer (LET). Protons and carbons are heavy ions with high LET. Since these ions lose energy through collisions as they move through the tissue, their range is not long. This loss of energy increases along the way, and the maximum energy loss is reached at the end of the range. This whole process is represented by the Bragg curve. The input dose of the Bragg curve, full width at half maximum (FWHM) value, Bragg peak amplitude and position, and Penumbra thickness are important factors in determining which particle is advantageous in tumor treatment. While heavy ions move through the tissue, small deviations occur in their direction of travel due to Coulomb collisions. These small deviations cause lateral straggle in the dose profile. Lateral straggle is important in determining the type and energy of the particle used in tumor treatments close to critical organs. In our study, when the water phantom of protons and carbon beams with different energies is taken into consideration, the input dose, FWHM value, peak amplitude and position, penumbra thickness and lateral straggle are calculated using the TRIM code and the results are compared with Monte Carlo (MC) simulation. It was found that the proton has an average of 63% more FWHM and 53% more Penumbra than the carbon ion. The carbon ion has an average of 28-45 times greater Bragg peak amplitude at the same Bragg peak location than the proton. It was observed that the proton scattered approximately 70% more in lateral straggle. The difference was found to be around 1.32 mm. In line with all these results, the most commonly used proton and carbon heavy ions in hadron therapy applications were compared.

Biomaterials are indispensable elements for improving human health and quality of life. Applications of biomaterials include the use of phantoms as tissue replacement in diagnostics (biosensors), medical supplies (blood bags and surgical instruments), therapeutic treatments (medical implants and devices), regenerative medicine (tissue engineered skin and cartilage), and radiation dosimetric studies. Since polymers are organic, they offer a much more versatile usage area than metals and ceramic biomaterials, particularly in soft tissue substitutes. The wide physical, mechanical, and chemical properties provided by polymers have encouraged extensive research, development, and application of polymeric biomaterials. Their usage as a soft tissue phantom is at the forefront of these applications. In this study, the ionization, recoils, phonon release, collision events, and lateral straggle properties of polymeric biomaterials [e.g., polymethylmetacrylate (PMMA), polystyrene, polyethylene, polypropylene, and polyvinylchloride] closest to soft tissue are investigated in carbon therapy application. The Brag peak location achieved for PMMA is quite close to that of soft tissue, within 4.8%, average recoils within 0.5%, and collision event parameter within 0.6%, however, lateral scattering is comparatively larger by roughly 6.8%, according to TRIM-based Monte Carlo simulation results. Thus, when carbon ion is taken into account, the current findings show that PMMA is one of the possible polymeric biomaterials to simulate soft tissue in terms of radiation interaction properties.

Given that there are 94 clinics and more than 200,000 patients treated worldwide, proton and carbon are the most used heavily charged particles in heavy-ion (HI) therapy. However, there is a recent increasing trend in using new ion beams. Each HI has a different effect on the target. As each HI moves through the tissue, they lose enormous energy in collisions, so their range is not long. Ionization accounts for the majority of this loss in energy. During this interaction of the heavily charged particles with the target, the particles do not only ionize but also lose energy with the recoil. Recoil occurs by atom-to-atom collisions. With these collisions, crystalline atoms react with different combinations and form cascades in accordance with their energies. Thus, secondary particles create ionization and recoil. In this study, recoil values of Boron(B), Carbon(C), Nitrogen(N), and Oxygen(O) beams in the water phantom were computed in the energy range of 2.0-2.5 GeV using Monte Carlo simulation and the results were compared with carbon. Our findings have shown that C beams have 35.3% more recoil range than B beams, while it has 14.5% and 118.7% less recoil range than N and O beams, respectively. The recoil peak amplitude of C beams is 68.1% more than B beams, while it is 13.1% less than N and 22.9% less than O beams. It was observed that there is a regular increase in the recoil peak amplitude for C and B ions, unlike O and N where such a regularity could not be seen. Moreover, the gaps in the crystal structure increased as the energy increases.

The Monte Carlo method is widely used in the Gamma Knife dose distribution calculations. In this study, Monte-Carlo simulation with Geant4 was applied to determine Leksell Gamma Knife dose distribution for homogeneous solid water and heterogeneous brain phantoms, and primarily focused on the differences arising from the effects of inhomogeneity. The relative dose graphs were displayed for different collimator diameters. The dose values from the maximal interval regions were determined and compared. It seen that when the collimator size was 4mm, the mean maximum relative dose point was at 47mm for water phantom and at 44mm for the brain. The difference found was about 6.38%. The differences among the results determined for water and brain were ranged from 2 to 17%. As a result, the inhomogeneity effect should be considered in dose calculation in Gamma Knife planning system.