Two determinations of the Ge-68 half-life

Status of the decay data for medical radionuclides: existing and potential diagnostic γ emitters, diagnostic β+ emitters and therapeutic radioisotopes

Recommended half-lives and specific well-defined emission energies and absolute emission probabilities are important input parameters that should be well-defined to assist in ensuring the diagnostic and therapeutic efficacy of individual radionuclides when applied in the field of nuclear medicine. Bearing in mind the nature of these requirements, approximately one hundred radionuclides have been considered and re-assessed as to whether their decay data are either adequately quantified, or require further in-depth measurements to improve their existing status and merit full re-evaluations of their decay schemes. The primary aim of such a review is to provide sufficient information on the existing and future requirements for such atomic and nuclear data.

Conductive nanocomposite hydrogel and mesenchymal stem cells for the treatment of myocardial infarction and non-invasive monitoring via PET/CT

Background

Injectable hydrogels have great promise in the treatment of myocardial infarction (MI); however, the lack of electromechanical coupling of the hydrogel to the host myocardial tissue and the inability to monitor the implantation may compromise a successful treatment. The introduction of conductive biomaterials and mesenchymal stem cells (MSCs) may solve the problem of electromechanical coupling and they have been used to treat MI. In this study, we developed an injectable conductive nanocomposite hydrogel (GNR@SN/Gel) fabricated by gold nanorods (GNRs), synthetic silicate nanoplatelets (SNs), and poly(lactide-co-glycolide)-b-poly (ethylene glycol)-b-poly(lactide-co-glycolide) (PLGA-PEG-PLGA). The hydrogel was used to encapsulate MSCs and ⁶⁸Ga³⁺ cations, and was then injected into the myocardium of MI rats to monitor the initial hydrogel placement and to study the therapeutic effect via ¹⁸F-FDG myocardial PET imaging.

Results

Our data showed that SNs can act as a sterically stabilized protective shield for GNRs, and that mixing SNs with GNRs yields uniformly dispersed and stabilized GNR dispersions (GNR@SN) that meet the requirements of conductive nanofillers. We successfully constructed a thermosensitive conductive nanocomposite hydrogel by crosslinking GNR@SN with PLGA₂₀₀₀-PEG₃₄₀₀-PLGA₂₀₀₀, where SNs support the proliferation of MSCs. The cation-exchange capability of SNs was used to adsorb ⁶⁸Ga³⁺ to locate the implanted hydrogel in myocardium via PET/CT. The combination of MSCs and the conductive hydrogel had a protective effect on both myocardial viability and cardiac function in MI rats compared with controls, as revealed by ¹⁸F-FDG myocardial PET imaging in early and late stages and ultrasound; this was further validated by histopathological investigations.

Conclusions

The combination of MSCs and the GNR@SN/Gel conductive nanocomposite hydrogel offers a promising strategy for MI treatment.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01432-7.

Nuclear model analysis of the 65Cu(α, n)68Ga reaction for the production of 68Ga up to 40 MeV

The charge particle (α) induced reactions on enriched copper (⁶⁵Cu) are investigated for the production of ⁶⁸Ga. The data sets of experimental cross sections are compiled, normalized and nuclear model analysis is done using calculational codes namely, ALICE-IPPE, TALYS 1.95 and EMPIRE 3.2. The theoretical production cross sections via alpha particle induced reactions are calculated to present a set of recommended cross sections. The calculated cross sections are utilized to deduce thick target yield (TTY) for the ⁶⁵Cu (α, n) ⁶⁸Ga reaction. The range of energy for production of ⁶⁸Ga is suggested up to 40 MeV having least contribution of radio-impurities.

2.7 years of beta-decay-rate ratio measurements in a controlled environment

We report nearly continuous beta-decay-rate measurements of Na-22, Cl-36, Co-60, Sr-90, and Cs-137 over a period of 2.7 years using four Geiger-Müller tubes. We carefully control the ambient pressure and temperature for the detectors, sources, and electronics in order to minimize environmentally-dependent systematic drifts in the measurement chains. We show that the amplitudes of an annual oscillation in the decay rates are consistent with zero to within 0.004%.