Claudio Tenreiro

Scope of Nanotechnology-based Radiation Therapy and Thermotherapy Methods in Cancer Treatment

The main aim of nanomedicine is to revolutionize the health care system and find effective approaches to fighting fatal diseases. Therapeutic beams, which are employed in radiation therapy, do not discriminate between normal and cancerous cells and must rely on targeting the radiation beams to specific cells. Interestingly, the application of nanoscale particles in radiation therapy has aimed to improve outcomes in radiation therapy by increasing toxicity in tumors and reducing it in normal tissues. This review focuses on approaches to nanotechnology-based cancer radiation therapy methods such as radionuclide therapy, photodynamic therapy, and neutron capture therapy. Moreover, we have investigated nanotechnology-based thermotherapy methods, including hyperthermia and thermoablation, as non-ionizing modalities of treatment using thermal radiation. The results strongly demonstrate that nanotechnology-based cancer radiation therapy and thermotherapy methods hold substantial potential to improve the efficacy of anticancer radiation and thermotherapy modalities.

Monte Carlo calculation of dosimetry parameters for the IR08-103Pd brachytherapy source.

PURPOSE For the treatment of some cancerous tumors using brachytherapy methods and low-energy photon sources, such as I125 and P103d, the American Association of Physicists in Medicine Task Group No. 43U1 report recommends that the dosimetric parameters of a new brachytherapy source must be determined in two experimental and Monte Carlo theoretical methods before using each new source clinically. This study presents the results of Monte Carlo calculations of the dosimetric parameters for IR08-P103d brachytherapy source design. IR08-P103d seed has been manufactured at the Agricultural, Medical and Industrial Research School. METHODS Version 5 of the (MCNP) Monte Carlo radiation transport code was used to calculate the dosimetry parameters around the source. Three geometric models of the seed, based on different locations of beads inside the titanium capsule, were simulated. The seed contains five resin beads of 0.6 mm diameter having P103d uniformly absorbed in the bead volume, which were contained within a cylindrical titanium capsule having 0.8 mm outside diameter and 4.8 mm length. RESULTS The Monte Carlo calculated dose rate constant Λ of the IR08-P103d seed was found to be 0.695±0.021cGyU-1h-1. Also in this study, the geometry function G(r,θ), line and point-source radial dose functions gL(r) and gP(r), and the anisotropy function F(r,θ), have been calculated at distances from 0.25 to 7 cm. The results of these calculations have been compared with measured values for an actual IR08-P103d seed. CONCLUSIONS There are no statistical significant dosimetric differences among the three seed orientations in this study (i.e., ideal, vertical, and diagonal). However, the observed differences between the calculated and measured values could be explained by the measurement uncertainty and the configuration of the resin beads within the capsule and capsule orientation.

Radiochemical studies relevant to the no-carrier-added production of 61,64Cu at a cyclotron

Copper-64 (t½ = 12.7 h) is a promising cancer treatment radiotherapy agent and combines positron emission tomography (PET). It was produced utilizing the 64Ni(p,n) 64Cu nuclear reaction channel. Natural nickel was electroplated successfully, 48 μm thick, onto a gold-coated copper backing slab. Bombardment of nickel plated target was performed with 16 MeV protons at a current of 200 μA. Copper-64 together with copper-61 was separated from Ni and other non-isotopic impurities by ion exchange chromatography. The method of separation of radiocopper has been improved.

Preparation of radioactive praseodymium oxide as a multifunctional agent in nuclear medicine: expanding the horizons of cancer therapy using nanosized neodymium oxide.

ObjectiveMany studies have attempted to assess the significance of the use of the &bgr;−-particle emitter praseodymium-142 (142Pr) in cancer treatment. As praseodymium oxide (Pr2O3) powder is not water soluble, it was dissolved in HCl solution and the resultant solution had to be pH adjusted to be in an injectable radiopharmaceutical form. Moreover, it was shown that the nanosized neodymium oxide (Nd2O3) induced massive vacuolization and cell death in non-small-cell lung cancer. In this work, the production of 142Pr was studied and water-dispersible nanosized Pr2O3 was proposed to improve the application of 142Pr in nuclear medicine. Materials and methodsData from different databases pertaining to the production of 142Pr were compared to evaluate the accuracy of the theoretical calculations. Water-dispersible nanosized Pr2O3 was prepared using a poly(ethylene glycol) (PEG) coating or PEGylation method as a successful mode of drug delivery. Radioactive 142Pr2O3 was produced via a 141Pr(n,&ggr;)142Pr reaction by thermal neutron bombardment of the prepared sample. ResultsThere was good agreement between the reported experimental data and the data based on nuclear model calculations. In addition, a small part of nano-Pr2O3 particles remained in suspension and most of them settled out of the water. Interestingly, the PEGylated Pr2O3 nanoparticles were water dispersible. After neutron bombardment of the sample, a stable colloidal 142Pr2O3 was formed. ConclusionThe radioactive 142Pr2O3 decays to the stable 142Nd2O3. The suggested colloidal 142Pr2O3 as a multifunctional therapeutic agent could have dual roles in cancer treatment as a radiotherapeutic agent using nanosized 142Pr2O3 and as an autophagy-inducing agent using nanosized 142Nd2O3.

Prediction of 67Ga production using the Monte Carlo code MCNPX

The widely used Monte Carlo simulation code Monte Carlo N-Particle System (MCNPX) has been utilized to simulate the production of (67)Gallium via multiple nuclear reaction channels. Based on the MCNPX-generated, energy-dependent proton flux within a Zn target during irradiation, the (67)Ga production yield was determined. Theoretical calculations of the production yield using the stopping power from the SRIM (stopping and range of ions in matter) code were compared to the measurements from the MCNPX code. These results were in good agreement with reported data, thus confirming the usefulness and accuracy of MCNPX as a tool for the design and optimization of targets for the production of other radionuclides.

Monte Carlo calculated TG-60 dosimetry parameters for the {beta}{sup -} emitter {sup 153}Sm brachytherapy source

PURPOSE The formalism recommended by Task Group 60 (TG-60) of the American Association of Physicists in Medicine (AAPM) is applicable forβ sources. Radioactive biocompatible and biodegradable S153m glass seed without encapsulation is a β- emitter radionuclide with a short half-life and delivers a high dose rate to the tumor in the millimeter range. This study presents the results of Monte Carlo calculations of the dosimetric parameters for the S153m brachytherapy source. METHODS Version 5 of the (MCNP) Monte Carlo radiation transport code was used to calculate two-dimensional dose distributions around the source. The dosimetric parameters of AAPM TG-60 recommendations including the reference dose rate, the radial dose function, the anisotropy function, and the one-dimensional anisotropy function were obtained. RESULTS The dose rate value at the reference point was estimated to be9.21±0.6cGyh-1μCi-1. Due to the low energy beta emitted from S153m sources, the dose fall-off profile is sharper than the other beta emitter sources. The calculated dosimetric parameters in this study are compared to several beta and photon emitting seeds. CONCLUSIONS The results show the advantage of theS153m source in comparison with the other sources because of the rapid dose fall-off of beta ray and high dose rate at the short distances of the seed. The results would be helpful in the development of the radioactive implants using S153m seeds for the brachytherapy treatment.

Dosimetric parameters of the new design 103Pd brachytherapy source based on Monte Carlo study

In this study version 5 of the MCNP photon transport simulation was used to calculate the dosimetric parameters for new palladium brachytherapy source design following AAPM Task Group No. 43U1 report. The internal source components include four resin beads of 0.6 mm diameters with (103)Pd uniformly absorbed inside and one cylindrical copper marker with 1.5 mm length. The resin beads and marker are then encapsulated within 0.8 mm in diameter and 4.5 mm long cylindrical capsule of titanium. The dose rate constant, Λ, line and point-source radial dose function, g(L)(r) and g(P)(r), and the anisotropy function, F(r,θ) of the IR01-(103)Pd seed have been calculated at distances from 0.25 to 5 cm. All the results are in good agreement with previously published thermoluminescence-dosimeter measured values [3] for the source. The dosimetric parameters calculated in this work showed that in dosimetry point of view, the IR01-(103)Pd seed is suitable for use in brachytherapy of prostate cancer.

Thick tellurium electrodeposition on nickel-coated copper substrate for 124I production

Tellurium electrodeposition on a nickel-coated copper substrate was investigated for production of iodine-124. The electrodeposition experiments were carried out by the alkali plating baths. The optimum conditions of the electrodeposition of tellurium were as follows: 6 g l(-1) tellurium, pH=10, DC current density of ca. 8.55 mA cm(-2) and room temperature.

Variance Reduction of Monte Carlo Simulation in Nuclear Engineering Field

The Monte Carlo method is a numerical technique that using random numbers and proba‐ bility to solve problems. It represents an attempt to model nature through direct simulation for any possible results, by substituting a range of values (a probability distribution) for any factor that has inherent uncertainty. The method is named after the city in the Monaco prin‐ cipality, because of roulette, a simple random number generator. The name and the system‐ atic development of Monte Carlo method dates from about 1944.The name “Monte Carlo” refers to the Monte Carlo Casino in Monaco because of the similarity of statistical simulation to games of chance and was coined by Metropolis during the Manhattan Project of World War II, [1].

Prediction of 94mTc production for positron emission tomography studies using the Monte Carlo code MCNPX-2.6

In this study, a Monte Carlo code was used to simulate a proton beam flux to calculate the (94m)Tc production yield from the (94)Mo(p,n)(94m)Tc reaction. An experimental yield of 3.465 GBq/μAh was measured for 48 min of irradiation at 1μA. An estimated value of 3.048 GBq/μAh was calculated for the yield produced based on the MCNPX proton flux in the same situation. These results demonstrate the usefulness and precision of MCNPX as a tool to design targets for the production of PET radionuclides. The yield of isotopic impurities from the (94)Mo(p,xn)(94g, 93m, 93g)Tc reactions was also calculated by the MCNPX code.