Comparative study of 155Tb production via 155Dy precursor with p, d and α beams on natural targets for medical applications

Three different reactions with the use of natural targets are investigated to produce 155Tb for medical applications from the decay of its precursor 155Dy. The TALYS code has been exploited to optimize the cross section description and to improve the agreement with the full set of available data. The study is completed by a theoretical model for the two radio-chemical separations: optimal solutions are presented for the production of high quality 155Tb samples, guaranteed by the absence of the main contaminant, 156Tb.

Production of 68Ge, 68Ga, 67Ga, 65Zn, and 64Cu important radionuclides for medical applications: theoretical model predictions for α-particles with 66Zn at ≈10–40 MeV

Theoretical predictions were made using TALYS-1.95(G) and EMPIRE 3.2 reaction-model codes for 69Ge, 67Ge, and medically used 68Ge, 67Ga, 68Ga, 65Zn, 64Cu radionuclides produced in the interaction of α-projectile with 66Zn-target at 10–40 MeV α-energies. Pearson’s statistical coefficients showed moderate to strong positive correlations between the theoretically predicted and experimentally measured production cross sections for radionuclides with practical medical applications. Furthermore, the present results indicated that a medium-sized cyclotron and a single α + 66Zn system (projectile + target system) might be an option for optimized production of 68Ge, 68Ga, 67Ga, 65Zn, and 64Cu radionuclides.

Nuclear data for light charged particle induced production of emerging medical radionuclides

Whatever the radionuclide to be used in nuclear medicine, it is essential to know the expected yield during the production process, but also of all the possible radionuclidic impurities coproduced, that can have an impact on the product final quality, as well as in the related waste management. The availability of the majority of emerging radioisotopes, including the theranostic ones or pairs, is mainly limited by the fact that, for most of them, the optimal production route still needs to be strengthened if not defined in some cases. The aim of this work is to present a review on the charged particle induced nuclear cross sections to produce some emerging radionuclides for medical applications to show that all types of projectiles should be considered in the quest of producing medical radionuclides. An accurate analysis of the production routes is presented for some radionuclides (67Cu, 47Sc, 89Zr, 103Pd, 186gRe, 97Ru, 211At) chosen as examples to highlight (i) how the quality of the final product strongly depends on the chosen target/projectile/energy parameters set, (ii) how deuteron production routes may sometimes be more effective than the proton ones or lead to a different impurity profile and (iii) how α-particle beams may allow to bypass the limitations occurring when using Z = 1 beams. An overview of possible advantages and drawbacks of the cited production routes and of potential cross sections that still need to be measured, is also reported.

Special radionuclide production activities – recent developments at QST and throughout Japan

National Institutes for Quantum Science and Technology (QST), formerly known as the National Institute of Radiological Sciences (NIRS), has been engaged in work on radiopharmaceutical science using cyclotrons since 1974. Eight pioneering researchers founded the basis of this field of research at NIRS, and to the present, many researchers and technicians have accumulated both scientific and technical achievements, as well as inherited the spirit of research. Besides, in recent years, we have developed production systems with AVF-930 cyclotron for various ‘non-standard’ radioisotopes applied in both diagnosis and therapy. Here, we review the past 50 years of our activities on radioisotope and radiopharmaceutical development, as well as more recent activities.

An overview of nuclear data standardisation work for accelerator-based production of medical radionuclides in Pakistan

The standardisation of nuclear reaction cross section data is an integral part of optimisation of production routes of medical radionuclides. The production cross sections are available for the reactor and cyclotron produced radionuclides to be used for diagnostics or therapeutic procedures. The types of nuclear data needed, and the sources of their availability are summarized. The method of standardisation of charged-particle data is briefly described. A historical overview of research work in Pakistan in this direction is given. Examples of a few medically important radionuclides, such as 64Cu, 86Y, 89Zr, 103Pd, 186Re, etc., whose data were standardised and evaluated are highlighted. Calculated thick target yields from the recommended data are given. Some new directions in the nuclear data research are outlined.

In-Target Proton–Boron Nuclear Fusion Using a PW-Class Laser

Nuclear reactions between protons and boron-11 nuclei (p–B fusion) that were used to yield energetic α-particles were initiated in a plasma that was generated by the interaction between a PW-class laser operating at relativistic intensities (~3 × 1019 W/cm2) and a 0.2-mm thick boron nitride (BN) target. A high p–B fusion reaction rate and hence, a large α-particle flux was generated and measured, thanks to a proton stream accelerated at the target’s front surface. This was the first proof of principle experiment to demonstrate the efficient generation of α-particles (~1010/sr) through p–B fusion reactions using a PW-class laser in the “in-target” geometry.

Evaluation of nuclear reaction cross section data of proton and deuteron induced reactions on 75As, with particular emphasis on the production of 73Se

75Se (T1/2 = 120 d), 73gSe (T1/2 = 7.1 h) and 72Se (T1/2 = 8.4 d) are important radioisotopes of selenium, being used in tracer studies, PET investigations and as a generator parent, respectively. Cross section data for the formation of those radionuclides in proton and deuteron induced reactions on 75As were critically analyzed up to about 70 MeV. A well-developed evaluation methodology was applied to generate the statistically fitted cross sections, based on the critically analyzed literature experimental data and the theoretical cross section values of three nuclear model codes ALICE-IPPE, TAYLS 1.9, and EMPIRE 3.2. Using the fitted cross sections the integral yield of each radionuclide was calculated. For the estimation of impurities, the integral yield of each radionuclide was compared with the yields of the other two radionuclides over a given energy region, and therefrom the energy range was suggested for the high purity production of each of the radionuclides 75Se, 73Se and 72Se. For production of the very important non-standard positron emitter 73Se via the 75As(p,3n)73Se reaction, the optimum energy range was deduced to be E p = 40 → 30 MeV, with a thick target yield of 1441 MBq/μAh and the 72,75Se impurity level of <0.1%.

Validation of nuclear reaction models for incident α-particles

Two different models allowing the calculation of reaction products are confronted with data from α-particle induced reactions. Both models contain a pre-equilibrium part and an equilibrium or compound nucleus part. The models are the exciton model in form of a code written by the author and TALYS. The other model is the intranuclear cascade model in form of the Liege-Saclay formulation incorporated in the PHITS code. The data are angle-integrated proton spectra from reactions with α-particle energies below 720 MeV and excitation functions from multi neutron emission with α-particle energies below 200 MeV.

An investigation of the effects of level density models and alpha optical model potentials on the cross-section calculations for the production of the radionuclides 62Cu, 67Ga, 86Y and 89Zr via some alpha induced reactions

Theoretical studies via nuclear reaction models have an undeniable importance and impact in terms of better understanding of reaction processes and their nature. In this study, by considering the importance of these models and the medical radionuclides, the effects of six level density models and eight alpha optical model potentials on the cross-section calculations for the production of the radionuclides 62Cu, 67Ga, 86Y and 89Zr via 59Co(α,n)62Cu, 60Ni(α,np)62Cu, 65Cu(α,2n)67Ga, 64Zn(α,p)67Ga, 85Rb(α,3n)86Y, 86Sr(α,n)89Zr, 87Sr(α,2n)89Zr and 88Sr(α,3n)89Zr reactions were investigated. Calculations for each reaction route were performed by using the TALYS v1.9 code. The most consistent model with the literature data taken from the Experimental Nuclear Reaction Database (EXFOR), was identified by using the reduced chi-squared statistics in addition to an eyeball estimation. Also, the effects of combinational use of selected models and potentials were investigated by comparing the calculational results with the experimental data.

Cross sections and production yields of 117mSn and other radionuclides generated in natural and enriched antimony with protons up to 145 MeV

Cross sections of a prospective medical radionuclide 117mSn along with 113Sn, 120m,122Sb, 111,114mIn and 118,119m,119g,121m,121g,123mTe generated in natural and enriched antimony targets by protons in a wide energy range up to 145 MeV were determined. A stacked-foil technique followed by gas chemical separation and γ-ray spectrometry were used. The obtained data were compared with experimental values reported in literature and with theoretical computations by ALICE, TALYS and Cascade-Evaporation-Fission codes. Production yields of 117mSn and the main impurity 113Sn were estimated for different irradiation modes.

Positron-emitting radionuclides for applications, with special emphasis on their production methodologies for medical use

A survey of the positron-emitting radionuclides over the whole mass range of the Periodic Table of Elements was carried out. As already known, positrons are preferably emitted from light mass neutron deficient radionuclides. Their emission from heavier mass nuclides is rather rare. The applications of positron annihilation in three areas, namely materials research, plant physiology and medical diagnosis, are reported. The methods of production of positron emitters are discussed, with emphasis on radionuclides presently attracting more attention in theranostics and multimodal imaging. Some future perspectives of radionuclide development technologies are considered.

Radiochlorine: an underutilized halogen tool

Halogen radioisotopes have a variety of physical half-lives which are suitable for probing a wide variety of pharmacokinetic processes. Compared with other radiohalogens, relatively little work has been done with radiochlorine. However, high specific activity radioisotopes of chlorine are available from low energy cyclotron production in quantities suitable for positron emission tomography (PET) and fundamental research. In particular, the sole radioisotope of chlorine which may be used for PET imaging, 34mCl, has achieved a state of development that permits imaging in clinical settings though sparse research effort has been focused on this isotope over the last 40 years. Additionally, the other longer-lived radioisotopes of chlorine will likely continue to show utility for more traditional radiotracer studies and chemistry development.

Therapeutic Radiometals: Worldwide Scientific Literature Trend Analysis (2008⁻2018)

Academic journals have published a large number of papers in the therapeutic nuclear medicine (NM) research field in the last 10 years. Despite this, a literature analysis has never before been made to point out the research interest in therapeutic radionuclides (RNs). For this reason, the present study aims specifically to analyze the research output on therapeutic radiometals from 2008 to 2018, with intent to quantify and identify global trends in scientific literature and emphasize the interdisciplinary nature of this research field. The data search targeted conventional (¹³¹I, ⁹⁰Y, ¹⁷⁷Lu, ¹⁸⁸Re, ¹⁸⁶Re, ¹⁵³Sm, ⁸⁹Sr, ¹⁸⁶Er) and emergent (⁶⁷Cu, ⁴⁷Sc, ²²³Ra, ¹⁶⁶Ho, ¹⁶¹Tb, ¹⁴⁹Tb, ²¹²Pb/²¹²Bi, ²²⁵Ac, ²¹³Bi, ²¹¹At, ^117mSn) RNs. Starting from this time frame, authors have analyzed and interpreted this scientific trend quantitatively first, and qualitatively after.

Isolation of high purity 73Se using solid phase extraction after selective 4,5-[73Se]benzopiazselenol formation with aminonaphthalene

A fast and efficient process for the production of the PET radionuclide 73Se was developed using 75Se as a surrogate. 75Se was separated from proton irradiated arsenic trioxide by reaction with 2,3-diaminonaphthalene to 4,5-[75Se]benzopiazelenol. This compound was purified using SPE column chromatography and subsequently decomposed with hydrogen peroxide. For further chemical conversions [75Se]selenite was reduced to elemental [75Se]selenium by either using thiosulfate or sulfur dioxide. The recovery yield of 75Se from the target amounted to 43%. The utility of the isolated 75Se for radiosyntheses was demonstrated by the successful preparation of [75Se]selenomethionine. The methodology developed using 75Se was successfully transformed to 73Se.

Development of novel radionuclides for medical applications

Medical radionuclide production technology is well established. There is, however, a constant need for further development of radionuclides. The present efforts are mainly devoted to nonstandard positron emitters (eg, ⁶⁴ Cu, ⁸⁶ Y, ¹²⁴ I, and ⁷³ Se) and novel therapeutic radionuclides emitting low-range β^- particles (eg, ⁶⁷ Cu and ¹⁸⁶ Re), conversion or Auger electrons (eg, ^117m Sn and ⁷⁷ Br), and α particles (eg, ²²⁵ Ac). A brief account of various aspects of development work (ie, nuclear data, targetry, chemical processing, and quality control) is given. For each radionuclide under consideration, the status of technology for clinical scale production is discussed. The increasing need of intermediate-energy multiple-particle accelerating cyclotrons is pointed out.

Nuclear model analysis of excitation functions of α-particle induced reactions on In and Cd up to 60MeV with relevance to the production of high specific activity 117mSn

Excitation functions were calculated for the α-particle induced reactions ¹¹⁵In(α,x)^117mSn, ¹¹⁴Cd(α,n)^117mSn, ¹¹⁶Cd(α,3n)^117mSn and ^natCd(α,x)^117mSn to analyse the production of the medically important ^117mSn (T_½ = 13.6 d). For calculations three nuclear model codes (i.e. TALYS, EMPIRE and ALICE-IPPE) were used and the results were compared with the available experimental data. For the most important reaction, ¹¹⁶Cd(α,3n)^117mSn, evaluated data are presented. The yield and radionuclidic purity of ^117mSn from each reaction are discussed.

Excitation functions of proton induced nuclear reactions on natFe up to 16 MeV, with emphasis on radiochemical determination of low cross sections

Excitation functions for the formation of the radionuclides

Measurements of excitation functions of α-particle induced reactions on natNi: possibility of production of the medical isotopes 61Cu and 67Cu

Excitation functions of the natNi(α,x)60,61Cu and 64Ni(α,p)67Cu reactions were measured using the stacked-foil activation technique. The experimental data achieved were compared with literature data as well as with nuclear model calculations performed using the code TALYS-1.8. Integral yields from the respective thresholds to 44 MeV were deduced from the measured excitation curves. The >99% pure 61Cu can be produced using the energy window of Eα=20→7 MeV, the yield amounting to 116 MBq/μAh. After a 2 h cooling time, the short-lived 60Cu (T1/2=23 min) impurity will be reduced to <0.1%. Due to low isotopic abundance of 64Ni, the enriched 64Ni target would be needed for the production of 67Cu via the (α,p) reaction. The cost would, however, be very high. In a few cases, particularly above 24 MeV, we have given new data points. In general, our measurements have strengthened the database.

Nuclear data for production and medical application of radionuclides: Present status and future needs

INTRODUCTION

The significance of nuclear data in the choice and medical application of a radionuclide is considered: the decay data determine its suitability for organ imaging or internal therapy and the reaction cross section data allow optimisation of its production route. A brief discussion of reaction cross sections and yields is given.

STANDARD RADIONUCLIDES

The standard SPECT, PET and therapeutic radionuclides are enumerated and their decay and production data are considered. The status of nuclear data is generally good. Some existing discrepancies are outlined. A few promising alternative production routes of ^99mTc and ⁶⁸Ga are discussed.

RESEARCH-ORIENTED RADIONUCLIDES

The increasing significance of non-standard positron emitters in organ imaging and of low-energy highly-ionizing radiation emitters in internal therapy is discussed, their nuclear data are considered and a brief review of their status is presented. Some other related nuclear data issues are also mentioned.

PRODUCTION OF RADIONUCLIDES USING NEWER TECHNOLOGIES

The data needs arising from new directions in radionuclide applications (multimode imaging, theranostic approach, radionanoparticles, etc.) are considered. The future needs of data associated with possible utilization of newer irradiation technologies (intermediate energy cyclotron, high-intensity photon accelerator, spallation neutron source, etc.) are outlined.

CONCLUSION

Except for a few small discrepancies, the available nuclear data are sufficient for routine production and application of radionuclides. Considerable data needs exist for developing novel radionuclides for applications. The developing future technologies for radionuclide production will demand further data-related activities.