Speaker
Description
Aim
Recently there has been growing interest in the medical application of $^{97}$Ru isotope. It is intended to be useful for both diagnostic and therapeutic purposes due to its convenient physical properties ($T_{1/2}$ = 2.9 d, gamma lines 215.7 keV, 85.8% and 324.5 keV, 10.2%, decay 100% EC with no $\beta$+ to contribute to the dose). Its chemical properties are also favourable, as it has several degrees of oxidation (II, III, IV, VIII) and forms more stable compounds compared to the conventional $^{99m}$Tc [Zaitseva, 1996]. Therefore, there are already many $^{97}$Ru-labeled radiopharmaceuticals successfully used for different prolonged examinations [Mukhopadhyay, 2011].
Materials and methods
Presently, there are different identified routes to produce $^{97}$Ru, with the use of neutron and charge particle induced reactions [Lahiri, 2016]. In this work, we focus on the $\alpha$-induced nuclear reactions on $^{nat}$Mo target in order to extend the available data above 40 MeV, in coherence with $\alpha$ beam available at our facility. The irradiation of $^{nat}$Mo stack foils was performed at ARRONAX, with the $\alpha$-beam of 67.4 MeV. The energy straggling in the last foil was calculated to be 0.75 MeV. The irradiated foils were measured via $\gamma$-ray spectroscopy techniques.
Results and discussion
We have measured the cross-section for the α-induced reactions on $^{nat}$Mo in the energy range 67 – 42 MeV. Our results indicate that for example the irradiation of 250 µm $^{nat}$Mo with 65 MeV $\alpha$-beam will yield around 10 MBq/$\mu$Ah (0.27 mCi/$\mu$Ah) of $^{97}$Ru. Most importantly, the use of such high energy prevents the formation of long-lived contaminant $^{103}$Ru ($T_{1/2}$ = 39.35 d). Although the yield of 0.27 mCi/$\mu$Ah is lower compared to the $^{103}$Rh(p,x)$^{97}$Ru reaction with around 1.3 mCi/$\mu$Ah [Lagunas-Solar, 1982], it allows to use the cheaper target with better thermal properties. Therefore the method to produce $^{97}$Ru via $^{nat}$Mo($\alpha$,x) might be considered in certain cases.
References
- Lagunas-Solar, M., Avalia, M., Navarro, N., Johnson, P., 1982. Cyclotron Production of No-carrier-added $^{97}$Ru by Proton Bombardment of $^{103}$Rh Targets. Int. J. Appl. Radiat. Isot., vol. 34, No. 6, p. 915
- Lahiri, S., 2016. Across the energy scale: from eV to GeV. J. Radioanal. Nucl. Chem., vol. 307, p. 1571.
- Mukhopadhyay, B., Mukhopadhyay, K., 2011. Applications of the Carrier Free Radioisotopes of Second Transitions Series Elements in the Field of Nuclear Medicine. J. Nucl. Med. Radiat. Ther., vol. 2:2
- Zaitseva, N. G, Stegailov, V. I., Khalkin, V. A., Shakun, N. G., Shishlyannikov, P. T., Bukov, K. G., 1996. Metal Technetium Target and Target Chemistry for the Production of $^{97}$Ru via the $^{99}$Tc(p,3n)$^{97}$Ru Reaction. Appl. Radiat. Isot., vol. 47, No. 2., p. 145
