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US-12618122-B2 - Recovery method of Ra-226, production method of Ra-226 solution, and Ac-225 solution production method of Ac-225 solution

US12618122B2US 12618122 B2US12618122 B2US 12618122B2US-12618122-B2

Abstract

One aspect of the present invention relates to a recovery method of 226 Ra, and the recovery method of 226 Ra includes a step (A1) of immersing a solid-state 226 Ra containing substance and a carrier having a function of adsorbing 226 Ra ions in a processing solution, and then irradiating the processing solution with ultrasonic waves.

Inventors

  • Yoshio Honda
  • Taku Ito
  • Jun Ichinose
  • Kotaro Nagatsu
  • Hisashi Suzuki

Assignees

  • NIHON MEDI-PHYSICS CO., LTD.
  • National Institutes for Quantum Science and Technology

Dates

Publication Date
20260505
Application Date
20211227
Priority Date
20210108

Claims (9)

  1. 1 . A recovery method of 226 Ra comprising a step (A1) of immersing a solid-state 226 Ra-containing substance and a carrier having a function of adsorbing 226 Ra ions in a processing solution to obtain a processing liquid, the processing liquid comprising the solid-state 226 Ra-containing substance, the carrier and the processing solution, and then irradiating the processing liquid with ultrasonic waves.
  2. 2 . The recovery method of 226 Ra according to claim 1 , wherein the solid-state 226 Ra-containing substance is at least one selected from the group consisting of uranium slag and a radium source.
  3. 3 . The recovery method of 226 Ra according to claim 1 , wherein the carrier exchanges 226 Ra ions.
  4. 4 . The recovery method of 226 Ra according to claim 1 , wherein the carrier contains an iminodiacetic acid group.
  5. 5 . The recovery method of 226 Ra according to claim 1 , further comprising: a step (A2) of separating the carrier from the processing solution; and a step (A3) of eluting 226 Ra from the carrier separated in the step (A2) using an acid.
  6. 6 . The recovery method of 226 Ra according to claim 5 , wherein the acid is at least one selected from the group consisting of hydrochloric acid and nitric acid.
  7. 7 . A production method of a 226 Ra solution, comprising: a step (A1) of immersing a solid-state 226 Ra-containing substance and a carrier having a function of adsorbing 226 Ra ions in a processing solution, and then irradiating the processing solution with ultrasonic waves; a step (A2) of separating the carrier from the processing solution; and a step (A3) of eluting 226 Ra from the carrier separated in the step (A2) using an acid.
  8. 8 . The recovery method of 226 Ra according to claim 1 , wherein a frequency of the ultrasonic waves is 16 kHz to 120 kHz.
  9. 9 . A production method of a 225 Ac solution, comprising: a step (B1) of obtaining a 226 Ra solution by the production method of a 226 Ra solution according to claim 7 ; and a step (B2) of producing a 225 Ac solution from the 226 Ra solution.

Description

TECHNICAL FIELD One aspect of the present invention relates to a recovery method of 226Ra, and a production method of a 226Ra solution or a production method of a 225Ac solution. BACKGROUND ART In the field of nuclear medicine, radioisotope (RI) internal therapy in which lesions such as tumors are treated by selectively incorporating a drug containing RI has been performed. Among the radiations, alpha rays have a short range, and thus have a characteristic that the effect of unnecessary radiation exposure on surrounding normal cells is small. 225Ac, which is one of the alpha-emitting nuclides, is a radionuclide with a half-life of 10 days, and has recently been expected as a therapeutic nuclide in cancer treatment. 225Ac is produced by, for example, a nuclear reaction of (p, 2n) by irradiating a 226Ra target with protons using an accelerator. Therefore, in order to produce 225Ac, 226Ra is required as a raw material of the 226Ra target. Until the early 1900s, 226Ra was produced in a factory from ore and was processed into radium sources for radiation therapy and the like applications, but in recent years, 226Ra has hardly been produced. Therefore, there is a need for a technique for recovering 226Ra from a substance containing 226Ra already produced, such as a radium source, and other naturally collected products containing 226Ra. In general, when 226Ra is recovered from a radium source, a method of collecting a part of a 226Ra-containing substance from a radium source, determining a chemical form of 226Ra contained in the radium source, and then extracting and recovering 226Ra by a treatment method suitable for the chemical form is known. For example, when the chemical form of 226Ra is radium sulfate, the radium sulfate is heated in a sodium carbonate aqueous solution to produce radium carbonate, the radium carbonate is filtered through a filter, and then the residue is washed and then dissolved with an acid to recover 226Ra. When the chemical form of 226Ra is radium chloride, the radium chloride is dissolved in water and 226Ra is recovered. When the chemical form of 226Ra is radium carbonate, the radium carbonate is filtered through a filter, and then the residue is washed and then dissolved with an acid to recover 226Ra. In addition, in Non Patent Literature 1, an attempt is made to isolate 226Ra from radium sulfate which is a solid, and the efficiency thereof is evaluated. CITATION LIST Non Patent Literature Non Patent Literature 1: Jan Kozempel et al., Dissolution of [226Ra] BaSO4 as part of a method for recovery of 226Ra from aged Radium sources., J. Radioanal. Nucl. Chem., 2015, 304, 337-342 SUMMARY OF INVENTION The methods of the related art described above have the following problems. The possibility of radiation exposure was high because the operation of collecting 226Ra samples from radium sources was difficult and complicated.It was also difficult to identify the chemical form of 226Ra, and it was not possible to select an appropriate treatment method in some cases.The conversion efficiency from radium sulfate to radium carbonate was not 100%, and the recovery rate of 226Ra was low because radium sulfate and radium carbonate were slightly dissolved in water.When a salt or a reagent used remained in the recovered 226Ra, there was a concern that the electrodeposition rate would decrease when 226Ra was electrodeposited for production of a 226Ra target. In Non Patent Literature 1, 226Ra has been successfully quantitatively isolated by several methods, but the reagent for adsorbing 226Ra used here, particularly EDTA, needs to be dissolved in water, and therefore, a step for separating 226Ra-EDTA from an aqueous matrix is required in a subsequent operation. In addition, since 226Ra and EDTA form a strong chelate bond, a step of releasing 226Ra from EDTA is required. Therefore, there is a problem that the step becomes complicated and the possibility of radiation exposure is high. One aspect of the present invention provides a recovery method of 226Ra, and a production method of a 226Ra solution or a production method of a 225Ac solution. One aspect of the present invention is a recovery method of 226Ra including a step (A1) of immersing a solid-state 226Ra-containing substance and a carrier having a function of adsorbing 226Ra ions in a processing solution, and then irradiating the processing solution with ultrasonic waves. In addition, another aspect of the present invention provides a production method of a 226Ra solution, the production method including: a step (A1) of immersing a solid-state 226Ra-containing substance and a carrier having a function of adsorbing 226Ra ions in a processing solution, and then irradiating the processing solution with ultrasonic waves; a step (A2) of separating the carrier from the processing solution; and a step (A3) of eluting 226Ra from the carrier separated in the step (A2) using an acid. Furthermore, still another aspect of the present invention is a production met