# US 12,763,229 B2 · Systems and methods for producing actinium-225

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- Number: US 12,763,229 B2
- Document ID: US12763229B2
- Status: Granted
- Kind: B2
- Application number: 17/602,056
- Filed: 2020-04-06
- Published: 2022-06-23
- Granted: 2026-10-13
- Earliest claimed: 2019-04-08
- Assignees: The Regents of the University of California
- Applicants: The Regents of the University of California
- Inventors: Lee Bernstein; Jon Batchelder; Jonathan T. Morrell; Andrew Voyles
- Web page: https://patentgrep.com/patent/US12763229B2

## CPC

- G21G 1/06: by neutron irradiation
- G21G 1/001: {Recovery of specific isotopes from irradiated targets}
- G21G 2001/0089: {Actinium}
- G21G: CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES (applications of radiation in general G21H5/00; handling particles, e.g. neutrons, or electromagnetic radiation not otherwise provided for G21K)

## Abstract

This disclosure provides systems, methods, and apparatus related to the production of actinium-225. In one aspect, a target is irradiated with a beam of deuterons to generate a beam of neutrons. A radium-226 target is irradiated with the beam of neutrons to generate radium-225.

## Claims

### Claim 1

A method comprising:
irradiating a target with a beam of deuterons to generate a beam of neutrons traveling in a direction parallel with a direction of the beam of deuterons, wherein the target comprises a beryllium target that is 4 millimeters to 8 millimeters thick;
irradiating a radium-226 target with the beam of neutrons to generate radium-225, wherein the beam of neutrons has a flux of 1×1010 neutrons/cm2/sec to 3×1012 neutrons/cm2/sec;
waiting a period of time to allow at least some of the radium-225 to decay to actinium-225 by beta decay; and
separating, from unreacted radium-226 and the radium-225, the actinium-225.

### Claim 2 (depends on 1)

The method of claim 1, wherein the radium-226 reacts to form the radium-225 by a (n, 2n) reaction.

### Claim 3 (depends on 1)

The method of claim 1, wherein the period of time is 15 days.

### Claim 4 (depends on 1)

The method of claim 1, wherein after the separating, the actinium-225 does not include any actinium-227.

### Claim 5 (depends on 1)

The method of claim 1, wherein after the separating, the actinium-225 consists essentially of actinium-225.

### Claim 6 (depends on 1)

The method of claim 1, wherein irradiating the radium-226 target occurs over a period of time of at least 1 day.

### Claim 7 (depends on 1)

The method of claim 1, wherein the target is disposed proximate the radium-226 target.

### Claim 8 (depends on 1)

The method of claim 1, wherein the target is positioned 0.5 millimeters to 10 millimeters from the radium-226 target.

### Claim 9 (depends on 1)

The method of claim 1, wherein the target and the radium-226 target are not in contact.

### Claim 10 (depends on 1)

The method of claim 1, wherein the radium-226 target is 1 millimeter to 10 millimeters thick.

### Claim 11 (depends on 1)

The method of claim 1, wherein deuterons in the beam of deuterons have an energy of 25 MeV to 55 MeV.

### Claim 12 (depends on 1)

The method of claim 1, wherein irradiating the radium-226 target with the beam of neutrons does not generate any actinium-227 or any species that decays to actinium-227.

### Claim 13 (depends on 1)

The method of claim 1, wherein the beam of deuterons is generated using a cyclotron.

### Claim 14 (depends on 1)

The method of claim 1, wherein the radium-226 target is not positioned in a nuclear reactor.

### Claim 15 (depends on 1)

The method of claim 1, wherein the neutrons are not thermal neutrons generated in a nuclear reactor.

### Claim 16 (depends on 1)

The method of claim 1, wherein the neutrons are not generated by a spallation source.

### Claim 17 (depends on 1)

The method of claim 1, wherein the beam of neutrons irradiates one or more additional radionuclide targets placed downstream of the radium-226 target with respect to the direction of the beam of neutrons.

### Claim 18

A method comprising:
irradiating a target with a beam of deuterons to generate a beam of neutrons traveling in a direction parallel with a direction of the beam of deuterons, the beam of neutrons having a flux of 1×1010 neutrons/cm2/sec to 3×1012 neutrons/cm2/sec and neutrons in the beam of neutrons have an energy of 10 MeV or greater, wherein the target comprises a beryllium target that is 4 millimeters to 8 millimeters thick;
irradiating a radium-226 target with the beam of neutrons to generate radium-225;
waiting a period of time to allow at least some of the radium-225 to decay to actinium-225 by beta decay; and
separating, from unreacted radium-226 and the radium-225, the actinium-225.

### Claim 19 (depends on 18)

The method of claim 18, wherein the beam of neutrons irradiates one or more additional radionuclide targets placed downstream of the radium-226 target with respect to the direction of the beam of neutrons.