scholarly journals Calculation of radiation dose enhancement by gadolinium compounds for radiation therapy

2022 ◽  
Vol 2155 (1) ◽  
pp. 012030
Author(s):  
G.A. Abdullaeva ◽  
G.A. Kulabdullaev ◽  
A.A. Kim ◽  
A.F. Nebesny ◽  
D.O. Yuldashev
Keyword(s):  
Radiation Therapy ◽  
Contrast Agent ◽  
Biological Tissue ◽  
Radiation Energy ◽  
Dose Enhancement ◽  
X Ray ◽  
Photon Irradiation ◽  
Irradiation Energy ◽  
Gd Contrast Agent ◽  
Shell Ionization

Abstract In this study, we evaluate the features of dose enhancement with Gd contrast agent (Magnevist). Due to the increased relaxation time and high atomic number (z=64) Gd can be used in radiation therapy as a radiosensitizer. To perform a quantitative evaluation of the radiosensitization effect is determined a parameter called the dose enhancement factor - DEF. The DEF values were calculated based on the analysis of the mass absorption coefficients for gadolinium and biological tissue. An increase in DEF is observed when the radiation energy is higher than the K-shell ionization energy of Gd atoms. For the presence of 20315 ppm Gd contrast agent in biological tissue the dose enrichment factor is maximum DEF = 4.12 at photon irradiation energy 60 keV. Also, based on calculations for photon irradiation sources considered high degrees of dose enhancement occur for Am-241, Yb-196, and 100 kVp X-ray tube.

Calculation of the radiation dose absorbed by human biological tissue when using imaging equipment in radiоtherapy

2021 ◽  
pp. 56-59
Author(s):  
Irina M. Lebedenko ◽  
Sergej S. Khromov ◽  
Taras V. Bondarenko ◽  
Evgenij M. Chertenkov
Keyword(s):  
Monte Carlo ◽  
Radiation Therapy ◽  
Biological Tissue ◽  
Electron Accelerator ◽  
Absorbed Dose ◽  
Tube Voltage ◽  
X Ray ◽  
The Monte Carlo Method ◽  
Therapeutic Procedures ◽  
Dose Control

Considered the issues of X-ray dose control during diagnostic and therapeutic procedures using imaging tools. The dose of X-ray radiation from the visualization devices absorbed by the biological tissue of a person was determined when monitoring the position of the patient on the therapeutic table of the electron accelerator before the radiation therapy session. The processes of transmission of photons and electrons through the medium were simulated, and the X-ray spectra were measured. The emission spectrum of the Varian G-242 Rotating Anode X-ray Tube was obtained using an XR-100-CdTe spectrometer. The absorbed dose is calculated by the Monte Carlo method. The absorbed dose in the water phantom at tube voltage up to 80 kV was 0,9–1,5 mGy.

scholarly journals Different distributions of gold nanoparticles on the tumor and calculation of dose enhancement factor by Monte Carlo simulation

2019 ◽  
Vol 5 (4) ◽  
pp. 361-371 ◽  
Author(s):  
Sajad Keshavarz ◽  
Dariush Sardari
Keyword(s):  
Gold Nanoparticles ◽  
Uniform Distribution ◽  
Enhancement Factor ◽  
Radiation Energy ◽  
Distribution Model ◽  
Distribution Models ◽  
Dose Enhancement ◽  
X Ray ◽  
Nanoparticle Distribution ◽  
Nanoparticle Sizes

Gold nanoparticles can be used to increase the dose of the tumor due to its high atomic number as well as being free from apparent toxicity. The aim of this study is to evaluate the effect of distribution of gold nanoparticles models, as well as changes in nanoparticle sizes and spectrum of radiation energy along with the effects of nanoparticle penetration into surrounding tissues in dose enhancement factor DEF. Three mathematical models were considered for distribution of gold nanoparticles in the tumor, such as 1-uniform, 2- non-uniform distribution with no penetration margin and 3- non-uniform distribution with penetration margin of 2.7 mm of gold nanoparticles. For this purpose, a cube-shaped water phantom of 50 cm size in each side and a cube with 1 cm side placed at depth of 2 cm below the upper surface of the cubic phantom as the tumor was defined, and then 3 models of nanoparticle distribution were modeled. MCNPX code was used to simulate 3 distribution models. DEF was evaluated for sizes of 20, 25, 30, 50, 70, 90 and 100 nm of gold nanoparticles, and 50, 95, 250 keV and 4 MeV photon energies. In uniform distribution model the maximum DEF was observed at 100 nm and 50 keV being equal to 2.90, in non-uniform distribution with no penetration margin, the maximum DEF was measured at 100 nm and 50 keV being 1.69, and in non-uniform distribution with penetration margin of 2.7 mm, the maximum DEF was measured at 100 nm and 50 keV as 1.38, and the results have been showed that the dose was increased by injecting nanoparticles into the tumor. It is concluded that the highest DEF could be achieved in low energy photons and larger sizes of nanoparticles. Non-uniform distribution of gold nanoparticles can increase the dose and also decrease the DEF in comparison with the uniform distribution. The non-uniform distribution of nanoparticles with penetration margin showed a lower DEF than the non-uniform distribution without any margin and uniform distribution. Meanwhile, utilization of the real X-ray spectrum brought about a smaller DEF in comparison to mono-energetic X-ray photons.

Study on the Size Dependence of AuNPs in Enhancement Radiation Effect for Superficial Kilovoltage X-Rays

2019 ◽  
Vol 290 ◽  
pp. 81-86
Author(s):  
Nur Shafawati binti Rosli ◽  
Azhar Abdul Rahman ◽  
Azlan Abdul Aziz ◽  
Shaharum Shamsuddin ◽  
Suhana Arshad
Keyword(s):  
Radiation Therapy ◽  
Free Radicals ◽  
Radiation Effects ◽  
Radiation Effect ◽  
Photoelectric Effect ◽  
Enhancement Effect ◽  
X Rays ◽  
Dose Enhancement ◽  
X Ray ◽  
Mcf 7

Radiation therapy and chemotherapy remain the most widely used treatment options in treating cancer. Recent developments in cancer research show that therapy combined with high-atomic number materials such as gold nanoparticles (AuNPs) is a new way to treat cancer, in which AuNPs are injected through intravenous administration and bound to tumor sites has enhanced tumor cell killing. Radiation therapy aims to deliver a high therapeutic dose of ionizing radiation to the tumor without exceeding normal tissue tolerance. In this work AuNPs have been used for the enhancement of radiation effects on breast cancer cells (MCF-7) for superficial kilovoltage X-ray radiation therapy. The use of AuNPs in superficial kilovoltage X-ray beams radiation therapy will provide a high probability for photon interaction by photoelectric effect. These provide advantages in terms of radiation dose enhancement. In this work, MCF-7 cells were seeded in the 96-well plate and treated with 13 nm, 50 nm and 70 nm AuNPs before they were irradiated with 80 kVp X-rays beam at various radiation doses. Photoelectric effect is the dominant process of interaction of 80 kVp X-rays with AuNPs. When the AuNPs are internalized into the MCF-7 cells, the dose enhancement effect is observed. The presence of AuNPs in the MCF-7 cells will produce a higher number of photoelectrons, and resulting more “free radicals” that will lead to increase in cell death. Then, these free radicals will lead to DNA damage to the MCF-7 cells. To validate the enhanced killing effect, both with and without AuNPs MCF-7 cells is irradiated simultaneously. By comparison, the results show that AuNPs significantly enhance cancer killing and the enhancement radiation effect was dependent on the size of AuNPs.

scholarly journals Effects of Nanoparticle Size and Radiation Energy on Copper-Cysteamine Nanoparticles for X-ray Induced Photodynamic Therapy

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1087
Author(s):  
Bindeshwar Sah ◽  
Jing Wu ◽  
Adam Vanasse ◽  
Nil Kanatha Pandey ◽  
Lalit Chudal ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Reactive Oxygen Species Production ◽  
Radiation Energy ◽  
Nanoparticle Size ◽  
Oxygen Species ◽  
X Rays ◽  
Therapy Outcomes ◽  
X Ray ◽  
Average Size ◽  
Species Production

The Copper-cysteamine (Cu-Cy) nanoparticle is a novel sensitizer with a potential to increase the effectiveness of radiation therapy for cancer treatment. In this work, the effect of nanoparticle size and the energy of X-rays on the effectiveness of radiation therapy are investigated. The effect of the particle size on their performance is very complicated. The nanoparticles with an average size of 300 nm have the most intense photoluminescence, the nanoparticles with the average size of 100 nm have the most reactive oxygen species production upon X-ray irradiation, while the nanoparticles with the average size of 40 nm have the best outcome in the tumor suppression in mice upon X-ray irradiation. For energy, 90 kVp radiation resulted in smaller tumor sizes than 250 kVp or 350 kVp radiation energies. Overall, knowledge of the effect of nanoparticle size and radiation energy on radiation therapy outcomes could be useful for future applications of Cu-Cy nanoparticles.

scholarly journals Effect of pulsed soft X-ray radiation on the surface topography of some metals

2021 ◽  
Vol 2064 (1) ◽  
pp. 012092
Author(s):  
A E Ligachev ◽  
M V Zhidkov ◽  
S A Sorokin ◽  
G V Potemkin ◽  
Yu R Kolobov
Keyword(s):  
Surface Topography ◽  
Surface Defects ◽  
Radiation Energy ◽  
High Current ◽  
Radiation Energy Density ◽  
Near Surface ◽  
Ion Flow ◽  
X Ray ◽  
Irradiation Energy ◽  
The Impact

Abstract Effect of the pulsed soft X-ray fluxes (PSXF) on the surface topography of metals (Mg and Cu) has been investigated. Soft pulse X-ray irradiation (energy quanta of 0.1-1.0 keV) were carried out on a high-current MIG generator. The sample of magnesium was located at a distance of 10 cm from the X-ray source. Since the distance to the sample significantly exceeded the size of the X-ray beam, it can be assumed that the density of the X-ray radiation flow to the magnesium sample was uniform. The duration of the radiation pulse was 100 ns, and the radiation energy density in the pulse varied from 13 to 19 J/cm2. As a result of melting under the action of PSXF of the near-surface layer of metals and subsequent solidification, a wavy relief is formed on their surface. Defects in the form of craters, which usually occur after the impact of a powerful pulsed ion flow on metals, were not detected.

scholarly journals A rebirth of radiation therapy with kV X-rays?

2019 ◽  
Vol 23 ◽  
pp. 85
Author(s):  
J. Kalef-Ezra
Keyword(s):  
Radiation Therapy ◽  
Experimental Models ◽  
X Rays ◽  
Dose Enhancement ◽  
X Ray ◽  
Normal Tissues ◽  
And Migration ◽  
Tissue Sparing ◽  
Dose Measurements ◽  
Therapy Studies

Novel clinical approaches using kV X-ray beams are currently under study, such as selective dose enhancement in malignant tissues due to the enhanced presence of atoms with high atomic number, Z, in tumors relative to normal tissues or the use of heavily spatially fractionated kV X-ray irradiation.Local dose enhancement by high Z atoms: A substantial dose gradient between normal and malignant tissues can be achieved by biologic targeting the cells to be “destroyed” with high Z atoms and its irradiation with photons in the energy region of tens of keV, such as synchrotron produced X-rays of energy above the K-edge. The selective accumulation of high Z atoms can be achieved by various techniques, such as by intravenous administration of a) contrast enhancement agents, b) some chemotherapeutic drugs c) nanoparticles and d) DNA precursors loaded with Z-atoms. Taking into account the limited availability and the high cost of GeV synchrotrons, brachytherapy sources could be used.Microbeam radiation therapy: Studies carried out in experimental models using spatially micro- fractionated beams have shown drastically elevated tissue radiation tolerance, with higher tissue sparing in healthy tissues than in malignant ones. This phenomenon is attributed by some investigators to the proliferation and migration of cells from the “low” dosed regions (~10 Gy) to the adjacent “heavily” dosed regions (many hundreds of grays). Multi-slit collimators allow for the production of X-ray microbeam arrays at 3rd generation synchrotron units. Monte Carlo simulations were tested versus direct dose measurements. Promising preclinical studies carried out so far, trigger studies on the development of alternative less expensive technologies.

scholarly journals Effect of Gold Nanoparticles on Dose Enhancement of 6 MV X-ray in MAGIC_f Polymer Gel Dosimeter

2018 ◽  
Author(s):  
S F Ghoreishi ◽  
J Beik ◽  
I Shiri ◽  
K Kh Keshavarzi ◽  
S R M Mahdavi
Keyword(s):  
Gold Nanoparticles ◽  
Radiation Therapy ◽  
Dose Distribution ◽  
Gel Dosimetry ◽  
Polymer Gel ◽  
Dose Enhancement ◽  
Gel Dosimeter ◽  
X Ray ◽  
Polymer Gel Dosimeter ◽  
Polymer Gel Dosimetry

Background:Currently, the potential application of gold nanoparticles (AuNPs) to increase the efficiency of radiation therapy has been widely investigated. However, lack of an appropriate method to estimate the dose distribution in a nanoparticle-laden tissue limits the applicability of nanoparticles in radiotherapy clinics. Polymer gel dosimetry provides an accurate and precise system that facilitates the measurement of dose distribution in full three dimensions.Objective: In this study, the effect of radiation dose enhancement of AuNPs was assessed through gel dosimetry analysis.Material and Methods: For this purpose, AuNPs were integrated in MAGIC_f polymer gel dosimeter and irradiated by 6 Mv X-ray beam. The irradiated gel was then evaluated through two modalities of magnetic resonance imaging (MRI) and optical computed tomography (OCT).Result: MRI and OCT scanning of MAGIC_f gels containing 0.1 mM AuNPs demonstrated dose enhancements of 7.8% and 6.8%, respectively.Conclusion: Polymer gel dosimetry has the potential to provide a new platform for the investigation and optimization of the applicability of nanoparticles in radiation therapy.

Effect of iodine contrast agent concentration on cerebrovascular dose for synchrotron radiation microangiography based on a simple mouse head model and a voxel mouse head phantom by Monte Carlo simulation

2016 ◽  
Vol 23 (1) ◽  
pp. 304-311 ◽  
Author(s):  
Hui Lin ◽  
Jia Jing ◽  
Yi-Fan Lu ◽  
Cong Xie ◽  
Xiao-Jie Lin ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Synchrotron Radiation ◽  
Contrast Agent ◽  
Iodine Concentration ◽  
Head Model ◽  
Enhancement Effect ◽  
Average Dose ◽  
Dose Enhancement ◽  
X Ray

Effective setting strategies using Monte Carlo simulation are presented to mitigate the irradiation damage in synchrotron radiation microangiography (SRA). A one-dimensional mouse head model and a segmented voxel phantom mouse head were simulated using theEGSnrc/DOSXYZnrccode to investigate the dose enhancement effect of an iodine contrast agent irradiated by a monochromatic synchrotron radiation source. The influence of the iodine concentration, vessel width and depth, protection with and without the skull layer, and various incident X-ray energies were all simulated. The dose enhancement effect and the absolute dose based on the segmented voxel mouse head phantom were evaluated. The dose enhancement ratio depended little on the irradiation depth, but strongly and linearly increasing on iodine concentration. The protection given by the skull layer cannot be ignored in SRA because a 700 µm-thick skull can decrease the dose by 10%. The incident X-ray energy can affect the dose significantly. Compared with a dose of 33.2 keV for 50 mgI ml−1, a dose of 32.7 keV decreased by 38%, whereas a dose of 33.7 keV increased by 69.2% and the variation strengthened more with enhanced iodine concentration. The segmented voxel mouse head phantom also showed that the average dose enhancement effect and the maximal voxel dose per photon depended little on the iodine voxel volume ratio but strongly on the iodine concentration. To decrease the damage caused by the dose in SRA, a high-Zcontrast agent should be used as little as possible and irradiation of the injection site of the contrast agent should be avoided immediately after the injection. The fragile vessel containing iodine should avoid being closely irradiated. Avoiding irradiating through a thin (or no) skull region, or attaching a thin equivalent material on the outside for protection are better methods. An incident X-ray energy as low as possible should be used as long as the SRA image quality is ensured. The use of the synergetic and synchronous shuttering technique in SRA is also very critical in order to effectively shorten the accumulative irradiation time inin vivoanimal irradiation experiments.

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