Experimental determination of proton-induced cross-sections on natural zirconium

Prospects for the production of radioisotopes and radiobioconjugates for theranostics

The development of diagnostic methods in medicine as well as the progress in the synthesis of biologically active compounds allows the use of selected radioisotopes for the simultaneous diagnosis and treatment of diseases, especially cancerous ones, in patients. This approach is called theranostic. This review article includes chemical and physical characterization of chosen theranostic radioisotopes and their compounds that are or could be useful in nuclear medicine.

Evaluation of nuclear reaction cross sections for optimization of production of the non-standard positron emitting radionuclide 90Nb using proton induced reactions on Zr target

Niobium-90 radionuclide is one of the promising candidates for the positron emission tomography (PET) technique. In this study, ⁹⁰Nb excitation functions via ⁹⁰Zr(p,n) and ^natZr(p,xn) reactions were computed using the TALYS-1.95 code based on phenomenological and microscopic level density models. The MCNPX simulation code was used for each case. Moreover, the target thicknesses were obtained using the SRIM-2013 code and the theoretical and simulation-based production yields of the ⁹⁰Nb were evaluated. The experimental production yield amounts of about 72.68 and 126.7 (both in MBq/μAh) for ⁹⁰Zr(p,n) and ^natZr(p,xn) reactions in the corresponding optimal energy windows were attained by our experiments respectively.

The Beginning and Development of the Theranostic Approach in Nuclear Medicine, as Exemplified by the Radionuclide Pair 86Y and 90Y

In the context of radiopharmacy and molecular imaging, the concept of theranostics entails a therapy-accompanying diagnosis with the aim of a patient-specific treatment. Using the adequate diagnostic radiopharmaceutical, the disease and the state of the disease are verified for an individual patient. The other way around, it verifies that the radiopharmaceutical in hand represents a target-specific and selective molecule: the "best one" for that individual patient. Transforming diagnostic imaging into quantitative dosimetric information, the optimum radioactivity (expressed in maximum radiation dose to the target tissue and tolerable dose to healthy organs) of the adequate radiotherapeutical is applied to that individual patient. This theranostic approach in nuclear medicine is traced back to the first use of the radionuclide pair 86Y/90Y, which allowed a combination of PET and internal radiotherapy. Whereas the β-emitting therapeutic radionuclide 90Y (t½ = 2.7 d) had been available for a long time via the 90Sr/90Y generator system, the β⁺ emitter 86Y (t½ = 14.7 h) had to be developed for medical application. A brief outline of the various aspects of radiochemical and nuclear development work (nuclear data, cyclotron irradiation, chemical processing, quality control, etc.) is given. In parallel, the paper discusses the methodology introduced to quantify molecular imaging of 86Y-labelled compounds in terms of multiple and long-term PET recordings. It highlights the ultimate goal of radiotheranostics, namely to extract the radiation dose of the analogue 90Y-labelled compound in terms of mGy or mSv per MBq 90Y injected. Finally, the current and possible future development of theranostic approaches based on different PET and therapy nuclides is discussed.

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.

Nuclear model analysis of excitation functions of proton induced reactions on ⁸⁶Sr, ⁸⁸Sr and natZr: Evaluation of production routes of ⁸⁶Y

The proton induced nuclear reactions on (86)Sr, (88)Sr and (nat)Zr were investigated for the production of (86)Y. The literature data were compared with the results of nuclear model calculations using the codes ALICE-IPPE, TALYS 1.6 and EMPIRE 3.2. The thick target yields of (86)Y were calculated from the recommended excitation functions. Analysis of radioyttrium impurities was also performed. A comparison of the various production routes showed that for medical applications of (86)Y, the reaction (86)Sr(p,n)(86)Y is the method of choice, which gives efficient yield with minimum impurities.

New activation cross section data on longer lived radio-nuclei produced in proton induced nuclear reaction on zirconium

The excitation functions of (96)Nb, (95m)Nb, (95g)Nb, (92m)Nb, (91m)Nb, (90)Nb, (95)Zr, (89)Zr, (88)Zr, (86)Zr, (88)Y, (87m)Y, (87g)Y, (86)Y were measured up to 70MeV proton energy by using the stacked foil technique and the activation method. The new data were compared with the critically analyzed experimental data in the literature and with the TALYS based model results in TENDL-2013 library. The possible role of the investigated reactions in the production of medically relevant (90)Nb, (95m)Nb, (89)Zr, and (88)Y radionuclides is discussed.