Isotopic composition of enriched Mo for production of medical Tc by Mo()Tc

Hashimoto, Shintaro; Nagai, Yasuki*

Journal of the Physical Society of Japan, 92(12), p.124202_1 - 124202_11, 2023/12

https://doi.org/10.7566/JPSJ.92.124202

Tc, which is a daughter nuclide of Mo, is used worldwide for medical imaging. However, there is a problem with the supply of Tc (Mo) due to the replacement of aging reactors. A method to produce Tc by irradiating Mo with protons using medical cyclotrons has been proposed. In this study, we presented a method to determine individual excitation functions for Mo()Tc using measured excitation functions for Mo()Tc. The method was validated by comparing estimated radionuclide purities of Tc in enriched Mo samples using the determined excitation functions with measured ones. In this study, we found that the content of Mo, Mo, and Mo should be low in order to produce Tc with high radionuclide purity. The results of this study play an important role in discussion of the required Mo compositions in enriched Mo, taking into account the constraints of each facility.

Large scale production of Cu and Cu via the Zn(n, p)Cu and Zn(n, np/d)Cu reactions using accelerator neutrons

Kawabata, Masako*; Motoishi, Shoji*; Ota, Akio*; Motomura, Arata*; Saeki, Hideya*; Tsukada, Kazuaki; Hashimoto, Shintaro; Iwamoto, Nobuyuki; Nagai, Yasuki*; Hashimoto, Kazuyuki*

Journal of Radioanalytical and Nuclear Chemistry, 330(3), p.913 - 922, 2021/12

https://doi.org/10.1007/s10967-021-07987-3

Both Cu and Cu are promising radionuclides in nuclear medicine. Production yields of these radionuclides were quantified by irradiating 55.4 g of natural zinc with accelerator neutrons. Clinically suitable Cu and Cu yields were estimated by experimental based numerical simulations using 100 g of enriched Zn and Zn, respectively, and elevated neutron fluxes from 40 MeV, 2 mA deuterons. A combined thermal- and resin-separation method was developed to isolate Cu and Cu from zinc, resulting in 73% separation efficiency and 97% zinc recovery. Such methods can provide large scale production of Cu and Cu for clinical applications.

Anomalous radioisotope production for ZnO using polyethylene by accelerator neutrons

Tsukada, Kazuaki; Nagai, Yasuki*; Hashimoto, Shintaro; Minato, Futoshi; Kawabata, Masako*; Hatsukawa, Yuichi*; Hashimoto, Kazuyuki*; Watanabe, Satoshi*; Saeki, Hideya*; Motoishi, Shoji*

Journal of the Physical Society of Japan, 89(3), p.034201_1 - 034201_7, 2020/03

https://doi.org/10.7566/JPSJ.89.034201

We found anomalously large yields of Ga, Ga, Zn and Cu by neutron irradiation on a ZnO sample in a polyethylene shield. Neutron beams are generated from the Be() reaction for 50 MeV deuterons. The yields obtained were more than 20 times larger than those in the unshielded sample. On the other hand, the yields of Ga, Ga, Zn and Cu from a metallic Zn sample and the yields of Cu, Ni and Zn from the ZnO and Zn samples were almost insensitive to the shield conditions. This finding would provide us a unique capability of accelerator neutrons to simultaneously produce a large amount of several radioisotopes, including proton induced reaction products, by using a single sample. The experimental data were compared with the yields estimated by using the Particle and Heavy Ion Transport code System and the result was discussed.

Measurement and estimation of the Mo production yield by Mo()Mo

Minato, Futoshi; Tsukada, Kazuaki; Sato, Nozomi*; Watanabe, Satoshi*; Saeki, Hideya*; Kawabata, Masako*; Hashimoto, Shintaro; Nagai, Yasuki*

Journal of the Physical Society of Japan, 86(11), p.114803_1 - 114803_6, 2017/11

https://doi.org/10.7566/JPSJ.86.114803

We have measured the yield of Mo, the mother nuclide of Tc used in nuclear diagnostic procedure. Mo was produced by Mo(,)Mo using neutrons with thermal energy up to about 40 MeV, provided by C(,). The Mo yield agrees with an estimated yield with the use of the latest data of C(,) and the evaluated cross section given in the JENDL. Based on this, a new calculation was carried out to produce Mo to seek for a good economical condition. Various conditions such as the MoO sample mass, the distance between the carbon target and the sample, the radius of the deuteron beam, and the neutron irradiation time were considered. The calculated Mo yield indicates that about 30% of the Mo demand in Japan can be fulfilled with a single accelerator. The elusion of Tc from the Mo twice per day would meet about 50% of the Mo demand.

Application of Cu produced by Zn()Cu to biodistribution study in tumor-bearing mice

Sugo, Yumi*; Hashimoto, Kazuyuki*; Kawabata, Masako*; Saeki, Hideya*; Sato, Shunichi*; Tsukada, Kazuaki; Nagai, Yasuki*

Journal of the Physical Society of Japan, 86(2), p.023201_1 - 023201_3, 2017/02

https://doi.org/10.7566/JPSJ.86.023201

Cu produced by the Zn()Cu reaction was used for the first time to determine the biodistribution of CuCl in colorectal tumor-bearing mice. High uptake of Cu was observed in the tumor as well as in the liver and kidney which are the major organs for copper metabolism. The result showing Cu accumulation in the tumor suggests that CuCl can be a potential radionuclide agent for cancer radiotherapy. It would also encourage further studies on the therapeutic effect in small animals using an increased dose of Cu produced by the Zn()Cu reaction using intense neutrons available at present.

Production of Tc for Compton camera imaging

Hatsukawa, Yuichi; Hashimoto, Kazuyuki; Tsukada, Kazuaki; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Nagai, Yasuki; Tanimori, Toru*; Sonoda, Shinya*; Kabuki, Shigeto*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1283 - 1285, 2015/02

https://doi.org/10.1007/s10967-014-3508-0

Technetium-99m (Tc) is used in radioactive medical diagonostic tests, for example as a radioactive tracer that medical equipment can detect in the human body. It is well suited to the role because it emits readily detectable 141 keV rays, and its half-life is 6.01 hours (meaning that about 94% of it decays to technetium-99 in 24 hours). There are at least 31 commonly used radiopharmaceuticals based on technetium-99m for imaging and functional studies of the brain, myocardium, thyroid, lungs, liver, gallbladder, kidneys, skeleton, blood, and tumors. Recent years, with the develop-ment of the Compton camera which can realize high position resolution, technetium isotopes emitting high energy -rays are required. In this study, technetium-95m which emits some rays around 800 keV was produced by the Mo(p,n)Tc reaction.

First measurement of the radionuclide purity of the therapeutic isotope Cu produced by Z(,) reaction using C(,) neutrons

Sato, Nozomi; Tsukada, Kazuaki; Watanabe, Satoshi; Ishioka, Noriko; Kawabata, Masako; Saeki, Hideya; Nagai, Yasuki; Kin, Tadahiro*; Minato, Futoshi; Iwamoto, Nobuyuki; et al.

Journal of the Physical Society of Japan, 83(7), p.073201_1 - 073201_4, 2014/07

https://doi.org/10.7566/JPSJ.83.073201

We have for the first time demonstrated that the therapeutic nuclide of Cu produced by Zn(,)Cu has highest radionuclide purity compared to previous ones. We measured a -ray spectrum of the reaction product produced by bombarding an enriched Zn sample with neutrons with a HPGe detector. The neutrons were obtained by C(,) using 41 MeV deuterons provided from Takasaki Ion Accelerators for Advanced Radiation Application of Japan Atomic Energy Agency. Relative production yields of impurity radionuclides such as Zn to Cu are extremely low, which allow us to chemically separate Cu from an irradiated Zn sample with a few steps and to reuse high cost an enriched Zn sample. The present result strongly suggest that the Zn(,)Cu reaction is the most promising route to produce high quality Cu and could solve a longstanding problem of establishing an appropriate production method of Cu.

Generation of medical radioisotopes using accelerator neutrons

Nagai, Yasuki; Hashimoto, Kazuyuki

Nihon Butsuri Gakkai-Shi, 69(6), p.370 - 375, 2014/06

https://doi.org/10.11316/butsuri.69.6_370

In Japan, about 0.9 million diagnostic procedures are carried out using Tc, the daughter nuclide of Mo with a half-life of 66 h, separated from Mo; all Mo radioisotopes are imported. Most of Mo has been produced by the fission reaction of highly enriched U in research reactors in the world. However, a number of incidents of the reactors caused the shortage of Mo worldwide, which triggered widespread discussions on the reliable supply of Mo. We proposed a new route to produce a large quantity of high quality Mo using fast neutrons from an accelerator.

Radionuclide production

Hashimoto, Kazuyuki; Nagai, Yasuki

Comprehensive Biomedical Physics, Vol.8, p.219 - 227, 2014/00

https://doi.org/10.1016/B978-0-444-53632-7.00614-6

Radionuclides for medical use are produced in nuclear reactors and in accelerators. The thermal neutron fluxes in nuclear reactors are several orders of magnitude higher than those of other neutron sources, such as accelerator neutrons. Hence, nuclear reactors have been playing important roles in the production of large quantity of medical radionuclides with their half-lives longer than several days. In accelerators, medical radionuclides with their half-lives longer than several minutes are produced. Recent progresses in accelerator technology as well as targetry technology, however, could enable one to obtain high-flux bremsstrahlung and intense energetic accelerator neutrons, and thereby to study new routes to produce medical radionuclides.

Generation of radioisotopes with accelerator neutrons by deuterons

Nagai, Yasuki; Hashimoto, Kazuyuki; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Sonoda, Nozomi; Kawabata, Masako; Harada, Hideo; Kin, Tadahiro*; Tsukada, Kazuaki; et al.

Journal of the Physical Society of Japan, 82(6), p.064201_1 - 064201_7, 2013/06

https://doi.org/10.7566/JPSJ.82.064201