A novel technique for simultaneous diagnosis and radioprotection by radioactive cerium oxide nanoparticles: study of cyclotron production of 137mCe

CeO2-Azacrown Conjugate as a Nanoplatform for Combined Radiopharmaceuticals

This study is one of the first attempts to assess CeO₂ nanoparticles as a nanoplatform for radiopharmaceuticals with radionuclides. The process of functionalization using a bifunctional azacrown ligand is described, and the resulting conjugates are characterized by IR and Raman spectroscopy. Their complexes with ²⁰⁷Bi show a high stability in medically relevant media, thus encouraging the further study of these conjugates in vivo as potential combined radiopharmaceuticals.

Study of activation cross sections of proton induced reactions on natBa and natCe near their threshold energy regions

Activation cross-sections of the nuclear reactions natBa(p,x)135,132gLa, 135mBa and natCe(p,x)142,139,138mPr, 141,139,137mCe have been measured experimentally at the MGC-20 cyclotron, Cairo, Egypt, from their respective threshold energies up to about 14.7 MeV. Stacked foil irradiation technique and high-resolution gamma-ray spectroscopy were used. A comparison between the experimental and theoretical data derived from the nuclear model codes EMPIRE and TALYS (in the form of the TENDL library) was performed. The agreement in the low-energy region is fairly good. Integral yields of the produced radioisotopes were estimated from the present cross-section data and the results are discussed in terms of their production possibilities.

64Cu, a powerful positron emitter for immunoimaging and theranostic: Production via natZnO and natZnO-NPs

⁶⁴Cu is one of the most beneficial radionuclide that can be used as a theranostic agent in Positron Emission Tomography (PET) imaging. In this current work, ⁶⁴Cu was produced with zinc oxide nanoparticles (^natZnONPs) and zinc oxide powder (^natZnO) via the ⁶⁴Zn(n,p)⁶⁴Cu reaction in Tehran Research Reactor (TRR) and the activity values were compared with each other. The theoretical activity of ⁶⁴Cu also was calculated with MCNPX-2.6 and the cross sections of this reaction were calculated by using TALYS-1.8, EMPIRE-3.2.2 and ALICE/ASH nuclear codes and were compared with experimental values. Transmission Electronic Microscopy (TEM), Scanning Electronic Microscopy (SEM) and X-Ray Diffraction (XRD) analysis were used for samples characterizations. From these results, it's concluded that ⁶⁴Cu activity value with nanoscale target was achieved more than the bulk state target and had a good adaptation with the MCNPX result.

Production and Clinical Applications of Radiopharmaceuticals and Medical Radioisotopes in Iran

During past 3 decades, nuclear medicine has flourished as vibrant and independent medical specialty in Iran. Since that time, more than 200 nuclear physicians have been trained and now practicing in nearly 158 centers throughout the country. In the same period, Tc-99m generators and variety of cold kits for conventional nuclear medicine were locally produced for the first time. Local production has continued to mature in robust manner while fulfilling international standards. To meet the ever-growing demand at the national level and with international achievements in mind, work for production of other Tc-99m-based peptides such as ubiquicidin, bombesin, octreotide, and more recently a kit formulation for Tc-99m TRODAT-1 for clinical use was introduced. Other than the Tehran Research Reactor, the oldest facility active in production of medical radioisotopes, there is one commercial and three hospital-based cyclotrons currently operational in the country. I-131 has been one of the oldest radioisotope produced in Iran and traditionally used for treatment of thyrotoxicosis and differentiated thyroid carcinoma. Since 2009, (131)I-meta-iodobenzylguanidine has been locally available for diagnostic applications. Gallium-67 citrate, thallium-201 thallous chloride, and Indium-111 in the form of DTPA and Oxine are among the early cyclotron-produced tracers available in Iran for about 2 decades. Rb-81/Kr-81m generator has been available for pulmonary ventilation studies since 1996. Experimental production of PET radiopharmaceuticals began in 1998. This work has culminated with development and optimization of the high-scale production line of (18)F-FDG shortly after installation of PET/CT scanner in 2012. In the field of therapy, other than the use of old timers such as I-131 and different forms of P-32, there has been quite a significant advancement in production and application of therapeutic radiopharmaceuticals in recent years. Application of (131)I-meta-iodobenzylguanidine for treatment of neuroblastoma, pheochromocytoma, and other neuroendocrine tumors has been steadily increasing in major academic university hospitals. Also (153)Sm-EDTMP, (177)Lu-EDTMP, (90)Y-citrate, (90)Y-hydroxyapatite colloid, (188/186)Re-sulfur colloid, and (188/186)Re-HEDP have been locally developed and now routinely available for bone pain palliation and radiosynovectomy. Cu-64 has been available to the nuclear medicine community for some time. With recent reports in diagnostic and therapeutic applications of this agent especially in the field of oncology, we anticipate an expansion in production and availability. The initiation of the production line for gallium-68 generator is one of the latest exciting developments. We are proud that Iran would be joining the club of few nations with production lines for this type of generator. There are also quite a number of SPECT and PET tracers at research and preclinical stage of development preliminarily introduced for possible future clinical applications. Availability of fluorine-18 tracers and gallium-68 generators would no doubt allow rapid dissemination of PET/CT practices in various parts of our large country even far from a cyclotron facility. Also, local production and availability of therapeutic radiopharmaceuticals are going to open exciting horizons in the field of nuclear medicine therapy. Given the available manpower, local infrastructure of SPECT imaging, and rapidly growing population, the production of Tc-99m generators and cold kit would continue to flourish in Iran.

Isotope Tracers To Study the Environmental Fate and Bioaccumulation of Metal-Containing Engineered Nanoparticles: Techniques and Applications

The rapidly growing applicability of metal-containing engineered nanoparticles (MENPs) has made their environmental fate, biouptake, and transformation important research topics. However, considering the relatively low concentration of MENPs and the high concentration of background metals in the environment and in organisms, tracking the fate of MENPs in environment-related scenarios remains a challenge. Intrinsic labeling of MENPs with radioactive or stable isotopes is a useful tool for the highly sensitive and selective detection of MENPs in the environment and organisms, thus enabling tracing of their transformation, uptake, distribution, and clearance. In this review, we focus on radioactive/stable isotope labeling of MENPs for their environmental and biological tracing. We summarize the advantages of intrinsic radioactive/stable isotopes for MENP labeling and discuss the considerations in labeling isotope selection and preparation of labeled MENPs, as well as exposure routes and detection of labeled MENPs. In addition, current practice in the use of radioactive/stable isotope labeling of MENPs to study their environmental fate and bioaccumulation is reviewed. Future perspectives and potential applications are also discussed, including imaging techniques for radioactive- and stable-isotope-labeled MENPs, hyphenated multistable isotope tracers with speciation analysis, and isotope fractionation as a MENP tracer. It is expected that this critical review could provide the necessary background information to further advance the applications of isotope tracers to study the environmental fate and bioaccumulation of MENPs.

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

OBJECTIVE

Many studies have attempted to assess the significance of the use of the β(-)particle emitter praseodymium-142 ((142)Pr) in cancer treatment. As praseodymium oxide (Pr(2)O(3)) 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 (Nd(2)O(3)) induced massive vacuolization and cell death in non-small-cell lung cancer. In this work, the production of (142)Pr was studied and water-dispersible nanosized Pr(2)O(3) was proposed to improve the application of (142)Pr in nuclear medicine.

MATERIALS AND METHODS

Data from different databases pertaining to the production of (142)Pr were compared to evaluate the accuracy of the theoretical calculations. Water-dispersible nanosized Pr(2)O(3) was prepared using a poly(ethylene glycol) (PEG) coating or PEGylation method as a successful mode of drug delivery. Radioactive (142)Pr(2)O(3) was produced via a (142)Pr(n,γ)(142)Pr reaction by thermal neutron bombardment of the prepared sample.

RESULTS

There was good agreement between the reported experimental data and the data based on nuclear model calculations. In addition, a small part of nano-Pr(2)O(3) particles remained in suspension and most of them settled out of the water. Interestingly, the PEGylated Pr(2)O(3) nanoparticles were water dispersible. After neutron bombardment of the sample, a stable colloidal (142)Pr(2)O(3) was formed.

CONCLUSION

The radioactive (142)Pr(2)O(3) decays to the stable (142)Nd(2)O(3). The suggested colloidal (142)Pr(2)O(3) as a multifunctional therapeutic agent could have dual roles in cancer treatment as a radiotherapeutic agent using nanosized (142)Pr(2)O(3) and as an autophagy-inducing agent using nanosized (142)Nd(2)O(3).

Monte Carlo characterization of 169Yb as a high-dose-rate source for brachytherapy application by FLUKA code

Higher initial dose rate and simplifying HDR room treatment of 169Yb element among other brachytherapy sources has led to investigating its feasibility as high‐dose‐rate seed. In this work, Monte Carlo calculation was performed to obtain dosimetric parameters of 169Yb, Model M42 source at different radial distances according to AAPM TG‐43U1 and HEBD Report about HDR sources in both air vacuum and spherical homogeneous water phantom. The deposited energy resulted by FLUKA as Monte Carlo code using binning estimators around 169Yb source was converted into radial dose rate distribution in polar coordinates surrounding the brachytherapy source. The results indicate a dose rate constant of 1.14±0.04cGy.h−1.U−1 with approximate uncertainty of 0.04%, air kerma strength, 1.082±2.6E−06U.mCi−1 and anisotropy function ranging from 0.386 to 1.00 for radial distances of 0.5–10 cm and polar angles of 0°–180°. Overall, FLUKA dosimetric outputs were benchmarked with those published by Cazeca et al. via MCNP5 as one of validate dosimetry datasets related to 169Yb HDR source. As a result, it seems that FLUKA code can be applicable as a valuable tool to Monte Carlo evaluation of novel HDR brachytherapy sources.

PACS number: 87.15.ak

Bremsstrahlung parameters of praseodymium-142 in different human tissues: a dosimetric perspective for (142)Pr radionuclide therapy

OBJECTIVE

Praseodymium-142 [T 1/2 = 19.12 h, [Formula: see text] = 2.162 MeV (96.3%), Eγ = 1575 keV (3.7%)] is one of the (141)Pr radioisotopes. Many studies have been attempted to assess the significance of usage (142)Pr in radionuclide therapy. In many studies, the dosimetric parameters of (142)Pr sources were calculated by modeling (142)Pr sources in the water phantom and scoring the energy deposited around it. However, the medical dosimetry calculations in water phantom consider Bremsstrahlung production, raising the question: "How important is to simulate human tissues instead of using water phantom?" This study answers these questions by estimation of (142)Pr Bremsstrahlung parameters.

METHODS

The Bremsstrahlung parameters of (142)Pr as therapeutic beta nuclides in different human tissues (adipose, blood, brain, breast, cell nucleus, eye lens, gastrointestinal tract, heart, kidney, liver, lung deflated, lymph, muscle, ovary, pancreas, cartilage, red marrow, spongiosa, yellow marrow, skin, spleen, testis, thyroid and different skeleton bones) were calculated by extending the national council for radiation protection model. The specific Bremsstrahlung constant (Γ Br), probability of energy loss by beta during Bremsstrahlung emission (P Br) and Bremsstrahlung activity (A release)Br were estimated. It should be mentioned that Monte Carlo simulation was used for estimation of (142)Pr Bremsstrahlung activity based on the element compositions of different human tissues and the calculated exposures from the anthropomorphic phantoms.

RESULTS

Γ Br for yellow marrow was smallest amount (1.1962 × 10(-3) C/kg-cm(2)/MBq-h) compared to the other tissues and highest for cortical bone (2.4764 × 10(-3) C/kg-cm(2)/MBq-h), and, overall, Γ Br for skeletal tissues were greater than other tissues. In addition, Γ Br breast was 1.8261 × 10(-3) C/kg-cm(2)/MBq-h which was greater than sacrum and spongiosa bones. Moreover, according to (A release)Br of (142)Pr, the patients receiving (142)Pr do not have to be hospitalized for radiation precautions and the Bremsstrahlung production does not prevent the therapy for outpatients.

CONCLUSION

However, modeling (142)Pr source in water phantom for simulation of (142)Pr source in soft tissues could be acceptable due to similarity of Γ Br in water and soft tissues; this approximation is a gross computation in the mediums encompassing high atomic numbers. These data may be practical in the investigation of Bremsstrahlung absorbed dose where (142)Pr is involved in radionuclide therapy.