Yoshitomo Inaba

Japan Atomic Energy Agency Japan

1. Introduction

Technetium-99m (99mTc, half-life: 6.01 hours) is the world’s most widely used

radiopharmaceutical for exams of cancer, bowel disease, brain faculty and so on, and it is used for more than twenty million exams per year in the world and more than one million exams per year in Japan. The demand for 99mTc is continuously growing up year by year. The features of 99mTc as the radiopharmaceutical are as follows:

1. It is easy to add 99mTc to diagnostic medicines.

2. It is easy to measure the y-ray energy with 0.14 MeV generated by isomeric transition from outside the body.

3. P rays are not emitted.

4. The patients’ exposure associated with the exams is kept to the minimum because of the short half-life.

The production of the short-lived 99mTc is conducted by extracting from molybdenum-99 (99Mo, half-life: 65.94 hours), which is the parent nuclide of 99mTc. Therefore, the stable production and supply of 99Mo is very important in every country. All of 99Mo used in Japan is imported from foreign countries. However, a problem has emerged that the supply of 99Mo is unstable due to troubles in the import and the aging production facility (Atomic Energy of Canada Limited [AECL], 2007, 2008). In order to solve the problem, the establishment of an efficient and low-cost 99Mo production method and the domestic production of 99Mo are needed in Japan.

As a major 99Mo production method, the fission method ((n, f) method) exists, and as a minor 99Mo production method, the neutron capture method ((n, y) method) exists. In order to apply to the Japan Materials Testing Reactor (JMTR) of the Japan Atomic Energy Agency (JAEA), two types of 99Mo production methods based on the (n, y) method have been developed in JAEA (Inaba et al., 2011): one is a solid irradiation method, and the other is a solution irradiation method, which was proposed as a new 99Mo production technique (Ishitsuka & Tatenuma, 2008).

The solution irradiation method aims to realize the efficient and low-cost production and the stable production and supply of 99Mo, and the fundamental research and development for the practical application of the method has been started (Inaba et al., 2009).

In this paper, a comparison between [22]Mo production methods, an overview of the solution irradiation method containing the structure of 99Mo production system with the method and the progress of the development made thus far, estimates of 99Mo production with the method, and the results of a newly conducted test are described.

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