A gallium scan is a type of

nuclear medicine Nuclear medicine (nuclear radiology, nucleology), is a medical specialty involving the application of radioactivity, radioactive substances in the diagnosis and treatment of disease. Nuclear imaging is, in a sense, ''radiology done inside out'', ...

diagnostic investigation that uses either a gallium-67 (⁶⁷Ga) or

gallium-68 Natural gallium (31Ga) consists of a mixture of two stable Isotope, isotopes: gallium-69 and gallium-71. Twenty-nine radioisotopes are known, all synthetic, with atomic masses ranging from 60 to 89; along with three nuclear isomer, nuclear isomer ...

(⁶⁸Ga)

radiopharmaceutical Radiopharmaceuticals, or medicinal radiocompounds, are a group of pharmaceutical drugs containing radioactive isotopes. Radiopharmaceuticals can be used as diagnostic and therapeutic agents. Radiopharmaceuticals emit radiation themselves, which ...

to obtain images of a specific type of tissue, or disease state of tissue. The

gamma emission A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

of gallium-67 is imaged by a

gamma camera A gamma camera (γ-camera), also called a scintillation camera or Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy. The applications of scintigraphy include early drug development ...

, while the

positron emission Positron emission, beta plus decay, or β+ decay is a subtype of radioactive decay called beta decay, in which a proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino (). Positron emi ...

of gallium-68 is imaged by

positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, r ...

(PET).

Gallium Gallium is a chemical element; it has Chemical symbol, symbol Ga and atomic number 31. Discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875, elemental gallium is a soft, silvery metal at standard temperature and pressure. ...

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

s like gallium

citrate Citric acid is an organic compound with the formula . It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry Biochemistry, or biological chemistry, is the study of chemical processes within and relati ...

and gallium

nitrate Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...

may be used. The form of salt is not important, since it is the freely dissolved gallium ion Ga³⁺ which is active. Both ⁶⁷Ga and ⁶⁸Ga salts have similar uptake mechanisms. Radioactive gallium(III) is rapidly bound by transferrin, which then preferentially accumulates in tumors, inflammation, and both acute and chronic infection, allowing these pathological processes to be imaged. Gallium is particularly useful in imaging

osteomyelitis Osteomyelitis (OM) is the infectious inflammation of bone marrow. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The feet, spine, and hips are the most commonly involved bones in adults. The cause is ...

that involves the spine, and in imaging older and chronic infections that may be the cause of a

fever of unknown origin Fever of unknown origin (FUO) refers to a condition in which the patient has an elevated temperature (fever) for which no cause can be found despite investigations by one or more qualified physicians. Mandell's Principles and Practices of Infection ...

. Due to lack of disease specificity, imaging with radioactive gallium(III) salts or simple complexes thereof, such as ⁶⁷Ga-citrate, has gradually become less important over time and is rarely used these days. However, the mentioned gallium(III) radionuclides, particularly ⁶⁸Ga, are frequently used as radiolabels for peptides, proteins, oligonucleotides, drugs, and drug-like substance, turning these from regular pharmaceuticals ito radiotracers. A popular class of such radiopharmaceuticals is formed by ⁶⁸Ga-labeled small-molecule inhibitors for prostate-specific membrane antigen (PSMA), which are increasingly used for prostate

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

imaging. Furthermore, Gallium-68 labeled octreotide analogs, such as ⁶⁸Ga-DOTATOC, were among the first clinically successful ⁶⁸Ga PET tracers and have meanwhile replaced

indium-111 Indium-111 (111In) is a radioactive isotope of indium (In). It decays by electron capture to stable cadmium-111 with a half-life of 2.8 days. Indium-111 chloride (111InCl) solution is produced by proton irradiation of a cadmium target (112Cd(p,2n ...

labeled octreotides for diagnostic imaging of somatostatin receptor positive neuroendocrine tumors. Investigations with ⁶⁸Ga-labeled peptides etc. are however not commonly referred to as 'gallium scan'. Usually they are named after the addressed target or labeled bioligand, e.g., 'PSMA scan' or 'DOTATOC scan'.

Gallium citrate scan

In the past, the gallium scan was the

gold standard A gold standard is a backed currency, monetary system in which the standard economics, economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the ...

for

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). The name typically refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enlarged lymph node ...

staging, until it was replaced by

(PET) using ¹⁸F-fluorodeoxyglucose (FDG). ⁶⁷Ga-citrate imaging is still used to image inflammation and chronic infections, and it still sometimes locates unsuspected tumors as it is taken up by many kinds of cancer cells in amounts that exceed those of normal tissues. Thus, an increased uptake of gallium-67 may indicate a new or old infection, an inflammatory focus from any cause, or a cancerous tumor. It has been suggested that gallium imaging may become an obsolete technique, with indium leukocyte imaging and technetium antigranulocyte antibodies replacing it as a detection mechanism for infections. For detection of

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s, especially lymphomas, gallium-67 imaging is still in use, but may be completely replaced by

Fluorodeoxyglucose []Fluorodeoxyglucose (International Nonproprietary Name, INN), or fluorodeoxyglucose F 18 (United States Adopted Name, USAN and United States Pharmacopeia, USP), also commonly called fluorodeoxyglucose and abbreviated []FDG, 2-[]FDG o ...

Fludeoxyglucose, 18F-fluorodeoxyglucose PET imaging in the future. In infections, the gallium scan has an advantage over indium leukocyte imaging in imaging

(bone infection) of the spine, lung infections and inflammation, and for chronic infections. In part this is because gallium binds to

neutrophil Neutrophils are a type of phagocytic white blood cell and part of innate immunity. More specifically, they form the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. Their functions vary in differe ...

membranes, even after neutrophil death. Indium leukocyte imaging is better for acute infections (where neutrophils are still rapidly and actively localizing to the infection), and also for osteomyelitis that does not involve the spine, and for

abdominal The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

and

pelvic The pelvis (: pelves or pelvises) is the lower part of an anatomical trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis or pelvic skeleton). ...

infections. Both the gallium scan and indium leukocyte imaging may be used to image

(elevated temperature without an explanation). However, the indium leukocyte scan will image only the 25% of such cases which are caused by acute infections, while gallium will also localize to other sources of fever, such as chronic infections and tumors.

Mechanism

The body generally handles Ga³⁺ as though it were

ferric In chemistry, iron(III) or ''ferric'' refers to the chemical element, element iron in its +3 oxidation number, oxidation state. ''Ferric chloride'' is an alternative name for iron(III) chloride (). The adjective ''ferrous'' is used instead for i ...

iron (Fe-III), and thus the free isotope ion is bound (and concentrates) in areas of inflammation, such as an infection site, and also areas of rapid cell division. Gallium (III) (Ga³⁺) binds to

transferrin Transferrins are glycoproteins found in vertebrates which bind and consequently mediate the transport of iron (Fe) through blood plasma. They are produced in the liver and contain binding sites for two Iron(III), Fe3+ ions. Human transferrin is ...

leukocyte White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...

lactoferrin Lactoferrin (LF), also known as lactotransferrin (LTF), is a multifunctional protein of the transferrin family. Lactoferrin is a globular proteins, globular glycoprotein with a molecular mass of about 80 Atomic mass unit, kDa that is widely repre ...

bacterial Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...

siderophore Siderophores (Greek: "iron carrier") are small, high-affinity iron- chelating compounds that are secreted by microorganisms such as bacteria and fungi. They help the organism accumulate iron. Although a widening range of siderophore functions is n ...

s, inflammatory proteins, and cell-membranes in neutrophils, both living and dead. Lactoferrin is contained within leukocytes. Gallium may bind to lactoferrin and be transported to sites of inflammation, or binds to lactoferrin released during bacterial

phagocytosis Phagocytosis () is the process by which a cell (biology), cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs ph ...

at infection sites (and remains due to binding with

macrophage Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...

receptors). Gallium-67 also attaches to the siderophore molecules of bacteria themselves, and for this reason can be used in leukopenic patients with bacterial infection (here it attaches directly to bacterial proteins, and leukocytes are not needed). Uptake is thought to be associated with a range of tumour properties including transferring receptors, anaerobic tumor metabolism and tumor perfusion and

vascular permeability Vascular permeability, often in the form of capillary permeability or microvascular permeability, characterizes the permeability of a blood vessel wall–in other words, the blood vessel wall's capacity to allow for the flow of small molecules ( ...

Common indications

*Whole-body survey to localize source of fever in patients with fever of unknown origin. *Detection of

pulmonary The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...

and

mediastinal The mediastinum (from ;: mediastina) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is a region that contains vital organs and structures within the thorax, mainly the heart and its vessels, the eso ...

inflammation/infection, especially in the

immunocompromised Immunodeficiency, also known as immunocompromise, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affe ...

patient. *Evaluation and follow-up of active lymphocytic or

granulomatous A granuloma is an aggregation of macrophages (along with other cells) that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such subst ...

inflammatory processes such as

sarcoidosis Sarcoidosis (; also known as Besnier–Boeck–Schaumann disease) is a disease involving abnormal collections of White blood cell, inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph n ...

tuberculosis Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...

. *Diagnosing vertebral osteomyelitis and/or disk space infection where gallium-67 is preferred over labeled leukocytes. *Diagnosis and follow-up of medical treatment of

retroperitoneal fibrosis Retroperitoneal fibrosis or Ormond's disease is a disease featuring the proliferation of fibrous tissue (fibrosis) in the retroperitoneum, the compartment of the body containing the kidneys, aorta, renal tract, and various other structures. It m ...

. *Evaluation and follow-up of drug-induced

pulmonary toxicity Pulmonary toxicity is the medical name for side effects on the lungs. Although most cases of pulmonary toxicity in medicine are due to side effects of medicinal drugs, many cases can be due to side effects of radiation (radiotherapy). Other (non-me ...

(e.g. Bleomycin, Amiodarone) *Evaluation of patients who are not candidates for WBC scans (WBC count less than 6,000). Note that all of these conditions are also seen in PET scans using the gallium-68.

Technique

The main (⁶⁷Ga) technique uses

scintigraphy Scintigraphy (from Latin ''scintilla'', "spark"), also known as a gamma scan, is a diagnostic test in nuclear medicine, where radioisotopes attached to drugs that travel to a specific organ or tissue (radiopharmaceuticals) are taken internally a ...

to produce two-dimensional images. After the tracer has been injected, images are typically taken by a

at 24, 48, and in some cases, 72, and 96 hours later. Each set of images takes 30–60 minutes, depending on the size of the area being imaged. The resulting image will have bright areas that collected large amounts of tracer, because inflammation is present or rapid cell division is occurring.

Single-photon emission computed tomography Single-photon emission computed tomography (SPECT, or less commonly, SPET) is a nuclear medicine tomography, tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera ...

(SPECT) images may also be acquired. In some imaging centers, SPECT images may be combined with

computed tomography A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

(CT) scan using either fusion software or SPECT/CT hybrid cameras to superimpose both physiological image-information from the gallium scan, and anatomical information from the CT scan. A common injection dose is around 150 megabecquerels. Imaging should not usually be sooner than 24 hours as high background at this time produces false negatives. Forty-eight-hour whole body images are appropriate. Delayed imaging can be obtained even 1 week or longer after injection if bowel is confounding. SPECT can be performed as needed. Oral laxatives or enemas can be given before imaging to reduce bowel activity and reduce dose to large bowel; however, the usefulness of bowel preparation is controversial. 10% to 25% of the dose of gallium-67 is excreted within 24 hours after injection (the majority of which is excreted through the kidneys). After 24 hours the principal excretory pathway is colon. The "target organ" (organ that receives the largest radiation dose in the average scan) is the colon (large bowel). In a normal scan, uptake of gallium is seen in wide range of locations which do not indicate a positive finding. These typically include soft tissues,

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

, and bone. Other sites of localisation can be

nasopharyngeal The pharynx (: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates, though its ...

and lacrimal glands, breasts (particularly in

lactation Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The process ...

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

), normally healing wounds, kidneys, bladder and colon.

Gallium PSMA scan

The positron emitting isotope, ⁶⁸Ga, can be used to target prostate-specific membrane antigen (PSMA), a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

which is present in

prostate cancer Prostate cancer is the neoplasm, uncontrolled growth of cells in the prostate, a gland in the male reproductive system below the bladder. Abnormal growth of the prostate tissue is usually detected through Screening (medicine), screening tests, ...

cells. The technique has been shown to improve detection of

metastatic Metastasis is a pathogenic agent's spreading from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, ...

disease compared to

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

s. In December 2020, the U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respo ...

(FDA) approved ⁶⁸Ga PSMA-11 for medical use in the United States. It is

indicated In medicine, an indication is a valid reason to use a certain test, medication, procedure, or surgery. There can be multiple indications to use a procedure or medication. An indication can commonly be confused with the term diagnosis. A diagnosis ...

for positron emission tomography (PET) of prostate specific membrane antigen (PSMA) positive lesions in men with prostate cancer. It is manufactured by the UCLA Biomedical Cyclotron Facility. The FDA approved ⁶⁸Ga PSMA-11 based on evidence from two clinical trials (Trial 1/NCT0336847 identical to NCT02919111 and Trial 2/NCT02940262 identical to NCT02918357) of male participants with prostate cancer. Some participants were recently diagnosed with the prostate cancer. Other participants were treated before, but there was suspicion that the cancer was spreading because of rising prostate specific antigen or PSA. The trials were conducted at two sites in the United States. The FDA considers ⁶⁸Ga PSMA-11 to be a

first-in-class medication A first-in-class medication is a prototype drug that uses a "new and unique mechanism of action" to treat a particular medical condition. While the Food and Drug Administration's Center for Drug Evaluation and Research tracks first-in-class medic ...

Common indications

Gallium PSMA scanning is recommended primarily in cases of biochemical recurrence of prostate cancer, particularly for patients with low PSA values, and in patients with high risk disease where metastases are considered likely.

Technique

intravenous Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutr ...

administration of 1.8–2.2

megabecquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as an activity of one per second, on average, for aperiodic activity events referred to a radionuclide. For applicatio ...

s of ⁶⁸Ga PSMA-11 per

kilogram The kilogram (also spelled kilogramme) is the base unit of mass in the International System of Units (SI), equal to one thousand grams. It has the unit symbol kg. The word "kilogram" is formed from the combination of the metric prefix kilo- (m ...

of bodyweight is recommended. Imaging should commence approximately 60 minutes after administration with an acquisition from mid-thigh to the base of the skull.

Gallium DOTA scans

⁶⁸Ga

DOTA ''Dota'' is a series of strategy video games. The series began in 2003 with the release of ''Defense of the Ancients'' (''DotA''), a fan-developed multiplayer online battle arena (MOBA) custom map for the video game ''Warcraft III: Reign of Ch ...

conjugated

peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...

s (including ⁶⁸Ga

DOTA-TATE DOTA-TATE (DOTATATE, DOTA-octreotate, oxodotreotide, DOTA-(Tyr3)-octreotate, and DOTA-0-Tyr3-Octreotate) is an eight amino acid long peptide, with a covalently bonded DOTA bifunctional chelator. DOTA-TATE can be reacted with the radionuclides ...

, DOTA-TOC and DOTA-NOC) are used in

(PET) imaging of

neuroendocrine tumour Neuroendocrine tumors (NETs) are neoplasms that arise from cells of the endocrine (hormonal) and nervous systems. They most commonly occur in the intestine, where they are often called carcinoid tumors, but they are also found in the pancreas, lu ...

s (NETs). The scan is similar to the SPECT octreotide scan in that an octreotide-based

somatostatin Somatostatin, also known as growth hormone-inhibiting hormone (GHIH) or by #Nomenclature, several other names, is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G ...

analogue (such as

edotreotide Edotreotide (USAN, also known as (DOTA0- Phe1- Tyr3) octreotide, DOTA-TOC, DOTATOC) is a substance which, when bound to various radionuclides, is used in the treatment and diagnosis of certain types of cancer. When used therapeutically it is an ex ...

) is used as the

radioligand A radioligand is a microscopic particle which consists of a Radiopharmaceutical, therapeutic radioactive isotope and the cell-targeting compound - the ligand. The ligand is the target binding site, it may be on the surface of the targeted cancer c ...

, and there are similar indications and uses as ocreotide scans, however image quality is significantly improved. Somatostatin receptors are overexpressed in many NETs, so that the ⁶⁸Ga DOTA conjugated peptide is preferentially taken up in these locations, and visualised on the scan. As well as diagnosis and staging of NETs, ⁶⁸Ga DOTA conjugated peptide imaging may be used for planning and

dosimetry Radiation dosimetry in the fields of health physics and radiation protection is the measurement, calculation and assessment of the ionizing radiation dose absorbed by an object, usually the human body. This applies both internally, due to ingest ...

in preparation for

lutetium Lutetium is a chemical element; it has symbol Lu and atomic number 71. It is a silvery white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted am ...

-177 or

yttrium-90 Yttrium-90 () is a radioactive isotope of yttrium. Yttrium-90 has found a wide range of uses in radiation therapy to treat some forms of cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the ...

DOTA

therapy A therapy or medical treatment is the attempted remediation of a health problem, usually following a medical diagnosis. Both words, ''treatment'' and ''therapy'', are often abbreviated tx, Tx, or Tx. As a rule, each therapy has indications a ...

. In June 2016, Netspot (kit for the preparation of gallium Ga-68 dotatate injection) was approved for medical use in the United States. In August 2019, ⁶⁸Ga

injection (⁶⁸Ga DOTATOC) was approved for medical use in the United States for use with PET imaging for the localization of somatostatin receptor positive neuroendocrine tumors (NETs) in adults and children. The U.S.

(FDA) approved ⁶⁸Ga

(DOTATOC) based on evidence from three clinical trials (Trial 1/NCT#1619865, Trial 2/NCT#1869725, Trial 3/NCT#2441062) of 334 known or suspected neuro-endocrine tumors. The trials were conducted in the United States. Gallium (⁶⁸Ga) oxodotreotide was approved for medical use in Canada as Netspot in July 2019, and as Netvision in May 2022. The combination germanium (68Ge) chloride / gallium (68Ga) chloride was approved for medical use in the European Union in August 2024. Other gallium-68 based PET scanning agents may also be based on the principle of attaching peptides to chelators, such as the in-development drug Ga-68-Trivehexin.

Radiochemistry of gallium-67

Gallium-67 citrate is produced by a cyclotron. Charged particle bombardment of enriched Zn-68 is used to produce gallium-67. The gallium-67 is then complexed with citric acid to form gallium citrate. The half-life of gallium-67 is 78 hours. It decays by

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Th ...

, then emits de-excitation

gamma ray A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

s that are detected by a gamma camera. Primary emission is at 93

keV In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum. When us ...

(39% abundance), followed by 185 keV (21%) and 300 keV (17%). For imaging, multiple gamma camera energy windows are used, typically centred around 93 and 184 keV or 93, 184, and 296 keV.

Radiochemistry of gallium-68

Gallium-68 Natural gallium (31Ga) consists of a mixture of two stable Isotope, isotopes: gallium-69 and gallium-71. Twenty-nine radioisotopes are known, all synthetic, with atomic masses ranging from 60 to 89; along with three nuclear isomer, nuclear isomer ...

, which has a 68 minutes half-life, is produced in a

gallium-68 generator A germanium-68/gallium-68 generator is a device used to extract the positron-emitting isotope Gallium-68, 68Ga of gallium from a source of decaying germanium-68. The parent isotope Isotopes of germanium, 68Ge has a half-life of 271 days and can be ...

by decay of

germanium-68 Germanium (32Ge) has five naturally occurring isotopes, 70Ge, 72Ge, 73Ge, 74Ge, and 76Ge. Of these, 76Ge is very slightly radioactive, decaying by double beta decay with a half-life of 1.78 × 1021 years (130 billion times the age of the ...

with a 271 day half-life or by the irradiation of zinc-68 through a low energy cyclotron. Use of a generator means a supply of ⁶⁸Ga can be produced easily with minimal infrastructure, for example at sites without a

cyclotron A cyclotron is a type of particle accelerator invented by Ernest Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Januar ...

, commonly used to produce other PET isotopes. It decays by

and

into zinc-68. Maximum energy of positron emission is at 1.9 MeV.

References

{{DEFAULTSORT:Gallium Scan 2D nuclear medical imaging Radiation therapy Gallium Orphan drugs