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GALLIUM-68 RADIOPHARMACY IN NUCLEAR MEDICINE
Mehmonov G.
Khujaev S.
S.Kh.Egamediev
Institute of Nuclear Physics, Uzbekistan Academy of Science, Tashkent,
UzbekistanE-mail address: m.golibjon99@gmail.com (G.Mehmonov). Tel:
+998948369836
https://doi.org/10.5281/zenodo.14249202
Abstract.
Gallium-68 (
68
Ga) is a positron-emitting radionuclide that has
gained prominence in nuclear medicine due to its exceptional versatility in
diagnostic imaging and theranostics. Its unique physical and chemical properties
make it ideal for PET imaging, especially in cancer diagnostics. This article
provides an overview of
68
Ga's role in radiopharmacy, explores its production
methods and highlights its theranostic applications.
Keywords:
Gallium-68, Nuclear medicine, Cyclotron production,
Generator production Ge
68
/Ga
68
, Cancer diagnostics, Theranostics.
Introduction
Positron Emission Tomography (PET) has become an essential tool in
medical imaging, providing valuable insights into the div’s internal processes
and aiding in the detection and monitoring of diseases, particularly in oncology,
neurology and cardiology [1]. One of the most commonly used radionuclides in
PET is Gallium-68 (
68
Ga), known for its favorable imaging properties.
68
Ga has a
short half-life of 68 minutes, making it ideal for clinical use. It can be easily
incorporated into various radiopharmaceuticals, allowing for targeted imaging
of specific biological processes [2]. Gallium-68 predominantly decays via
positron emission, which accounts for approximately 89% of its total decay
process. The emitted positrons have a maximum energy of 1.92 MeV. The
remaining 11% of the decay occurs through electron capture, resulting in the
formation of the stable isotope zinc-68 (
68
Zn) [3].
Production
Gallium-68 (
68
Ga) is primarily produced using two methods: cyclotron-
based production and generator-based production. The most common method
for obtaining Gallium-68 is through the
68
Ge/
68
Ga parent/daughter radionuclide
generator. Fig-1. In this process, the parent isotope Germanium-68 (
68
Ge) is
produced by irradiating natural gallium (
69
Ga) with protons in a cyclotron,
resulting in the
69
Ga(p,2n)
68
Ge reaction.
68
Ge has a half-life of 270.95 days and
decays to
68
Ga, which is then extracted from the generator using a saline solution
[4, 5]. This method provides a reliable and on-demand source of
68
Ga, making it a
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widely used approach in both clinical and research settings for producing
radiopharmaceuticals. The
68
Ge/
68
Ga generator is especially advantageous in
settings where cyclotron facilities are not available, offering a cost-effective and
accessible means of producing
68
Ga for PET imaging.[6]
Figure 1. Typical generator system [7].
Gallium-68 can be produced from the cyclotron through different reactions
using various particles, such as protons, alpha and deuterons. Table 1. The most
common method to produce Gallium-68 (
68
Ga) involves the irradiation of
enriched zinc-68 (
68
Zn) with protons via the reaction
68
Zn(p:n)
68
Ga. This
approach is highly efficient and widely used for clinical and research
applications.[8] This approach is not only highly efficient but also offers
significantly higher production yields compared to generator-based methods.
The cross-section value for the
68
Zn(p:n)
68
Ga reaction is shown in Fig-2 and the
corresponding physical yield is also provided.
Table 1. production routes Ga 68 usng the cyclotron
Reaction
Energy rage
MeV
Q-value
MeV
Threshold
MeV
68
Zn(p:n)
68
Ga
3-14
-3.7
3.7
65
Cu(a:n)
68
Ga
4-27
-5.0
6.1
68
Zn(d:n)
68
Ga
5-18
-5.9
6.1
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4
8
12
16
20
0
200
400
600
800
1000
Cross-
sectio
n (
mb
)
Energy (MeV)
68
Zn(p:n)
68
Ga
0
4
8
12
16
20
0
2400
4800
7200
9600
12000
Physical Yield (
MBq/u
Ah)
Energy (MeV)
Ga 68
Figure 2. Cross-section value of
68
Zn(p:n)
68
Ga and physical Yield of
68
Ga.
Theranostic application
Theranostics combines diagnostic imaging and therapy and
68
Ga plays a
pivotal role in this field. For example,
68
Ga-labeled tracers are used for tumor
localization, while therapeutic isotopes such as Lutetium-177 (
177
Lu) are
employed for treatment. This diagnostic-therapeutic pairing, exemplified by the
68
Ga/
177
Lu-PSMA and
68
Ga/
177
Lu-DOTA-conjugates, allows for personalized
treatment planning and improved patient outcomes. [9]
68
Ga-PSMA is used in
prostate cancer diagnostics by targeting prostate-specific membrane antigens
(PSMA), which are commonly found on prostate cancer cells, enabling precise
tumor imaging.
68
Ga-DOTA-conjugated peptides (e.g., DOTA-TATE, DOTA-TOC,
DOTA-NOC) are used for imaging neuroendocrine tumors by binding to
somatostatin receptors, which are overexpressed on tumor cells, providing
accurate diagnostic information [10], shown in Fig-3.
Figure 3. Lutetium-177 Labelled PSMA Targeted Therapy
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Conclusion
Gallium-68 (
68
Ga) is a cornerstone in nuclear medicine, particularly for
PET imaging and theranostic applications. Its favorable properties, such as a
short half-life and efficient production methods, including both the
68
Ge/
68
Ga
generator and cyclotron-based techniques, make it a valuable tool in cancer
diagnostics.
68
Ga’s ability to pair with therapeutic isotopes, such as
177
Lu, in
theranostic approaches has revolutionized personalized treatment, allowing for
more accurate tumor localization and targeted therapy. As
68
Ga-based
radiopharmaceuticals continue to evolve, they are expected to significantly
improve diagnostic precision and treatment outcomes for various cancers.
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