Nuclear medicine

Nuclear Medicine

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Nuclear medicine

Nuclear medicine is a branch of medicine

Medicine

Medicine is the art and science of healing. It encompasses a range of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
and medical imaging

Medical imaging

Medical imaging refers to the techniques and processes used to create s of the human body for clinical purposes or medical science .As a discipline and in its widest sense, it is part of biological imaging and incorporates radiology , radiological sciences, endoscopy, thermography, medical photography and microscopy ....
that uses radioactive isotopes (radionuclides) in the diagnosis of disease. Nuclear medicine thus relies on the process of radioactive decay

Radioactive decay

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide....
. Molecular imaging

Molecular imaging

Molecular imaging originated from the field of radiopharmacology due to the need to better understand the fundamental molecular pathways inside organisms in a noninvasive manner....
may employ nuclear medical techniques when it uses radioisotopes to produce images that reflect biological processes that take place at the cellular and subcellular level.

Nuclear medicine procedures use pharmaceuticals that have been labeled with radionuclide

Radionuclide

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Encyclopedia

Nuclear medicine is a branch of medicine

Medicine

Medical imaging

Radioactive decay

Molecular imaging

Radionuclide

A radionuclide is an atom with an unstable Atomic nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron ....
s (radiopharmaceuticals). In diagnosis, radioactive substances are administered to patient

Patient

A patient is any person who receives medical attention, care, or Therapy. The person is most often illness or injured and in need of treatment by a physician or other Health care provider, although one who is visiting a physician for a routine check-up may also be viewed as a patient....
s and the radiation

Ionizing radiation

Ionizing radiation consists of subatomic particle radiation or electromagnetic radiation that are energetic enough to detach electrons from atoms or molecules, ionize them....
emitted is detected. The diagnostic tests involve the formation of an image using a gamma camera

Gamma camera

A gamma camera is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy. The applications of scintigraphy include early drug development and nuclear medicine to view and analyse images of the human body of the distribution of medically injected, inhaled, or ingested radionuclides emitting gamma rays...
or positron emission tomography

Positron emission tomography

Positron emission tomography is a nuclear medicine medical imaging technique which produces a three-dimensional image or picture of functional processes in the body....
, invented by Hal O. Anger, and sometimes called an Anger gamma camera, as well as single photon emission tomography SPECT. Imaging may also be referred to as radionuclide imaging or nuclear scintigraphy. Other diagnostic tests use probes to acquire measurements from parts of the body, or counters for the measurement of samples taken from the patient.

In therapeutic use, radionuclides may be administered to treat disease, or provide palliative

Palliative care

Palliative care is any form of medical care or treatment that concentrates on reducing the severity of disease symptoms, rather than striving to halt, delay, or reverse progression of the disease itself or provide a cure....
pain relief. However, the use of radionuclides in therapy, once a part of classical nuclear medicine, is now often formally merged with the practice of radiotherapy (Radiation therapy medicine), where radionuclides are used by practioners who also employ other sources of radiation. See radiotherapy for discussion of the therapeutic use of radioisotopes.

Nuclear medicical tests differ from most other imaging modalities in that diagnostic tests primarily show the physiological

Physiology

Physiology is the study of the mechanical, physical, and biochemical functions of living organisms. Physiology has traditionally been divided between plant physiology and animal and all living things physiology but the principles of physiology are universal, no matter what particular organism is being studied....
function of the system being investigated as opposed to traditional anatomical imaging such as CT

Computed tomography

Computed tomography is a medical imaging method employing tomography. Geometry Processing is used to generate a stereoscopy of the inside of an object from a large series of two-dimensional X-ray images taken around a single axis of rotation....
or MRI

Magnetic resonance imaging

GaneshMagnetic resonance imaging , or nuclear magnetic resonance imaging , is primarily a medical imaging technique most commonly used in radiology to visualize the structure and function of the body....
. In some centers, the nuclear medicine images can be superimposed, using software or hybrid cameras, on images from modalities such as CT

Computed tomography

Magnetic resonance imaging

GaneshMagnetic resonance imaging , or nuclear magnetic resonance imaging , is primarily a medical imaging technique most commonly used in radiology to visualize the structure and function of the body....
to highlight the part of the body in which the radiopharmaceutical is concentrated. This practice is often referred to as image fusion or co-registration.

Nuclear medicine diagnostic tests are usually provided by a dedicated department within a hospital

Hospital

A hospital is an institution for health care providing patient treatment by specialized staff and equipment, and often but not always providing for longer-term patient stays....
and may include facilities for the preparation of radiopharmaceuticals. The specific name of a department can vary from hospital to hospital, with the most common names being the nuclear medicine department and the radioisotope department. Nuclear medicine is a technologically embedded specialty that requires collaboration of not only physicians ( nuclear medicine physicians

Nuclear Medicine Physician

Nuclear Medicine Physicians are medical imaging specialists that use tracers, usually radiopharmaceuticals, for diagnosis and therapy. Nuclear medicine procedures are the major clinical applications of molecular imaging and molecular therapy....
or radiologists

Radiology

Radiology is the branch or speciality of medicine that deals with the study and application of imaging technology like x-ray and radiation to diagnosing and treating disease....
), technologists, and support personnel, but also medical physicists

Medical physics

File:Gamma knife.jpgMedical physics is the application of physics to medicine. It generally concerns physics as applied to medical imaging and radiotherapy, although a medical physicist may also work in many other areas of healthcare....
, engineers

Biomedical engineering

Biomedical engineering is the application of engineering principles and techniques to the medical field. It combines the design and problem solving skills of engineering with medical and biological sciences to help improve patient health care and the quality of life of individuals....
, radiochemists

Radiochemistry

Radiochemistry is the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes ....
, radiopharmacists

Radiopharmacology

Radiopharmacology is the study and preparation of radiopharmaceuticals, which are radioactivity pharmaceuticals. Radiopharmaceuticals are used in the field of nuclear medicine as tracers in the diagnosis and treatment of many diseases....
, radiobiologists

Radiobiology

Radiobiology is the interdisciplinary field of science that studies the biological effects of ionizing radiation and non-ionizing radiation radiation of the whole electromagnetic spectrum, including radioactivity , x-rays, ultraviolet radiation, visible light, microwaves, radio wave, low-frequency radiation ...
, and instrument manufacturers

Medical imaging

Source of radioisotopes

About two thirds of the world's supply of medical isotopes are produced at the Chalk River Laboratories

Chalk River Laboratories

The Chalk River Laboratories is a Canada nuclear reaction research facility located near Chalk River, Ontario, about 180 km North-West of Ottawa....
in Chalk River

Chalk River

Chalk River can refer to either:*Chalk River Laboratories*Chalk River, Ontario, a town in the upper Ottawa River valley where the Chalk River Laboratories are located....
, Ontario

Ontario

Ontario is a Provinces and territories of Canada located in the Central Canada part of Canada, the largest by population and second largest, after Quebec, in total area....
, Canada

Canada

Canada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean....
. The Canadian Nuclear Safety Commission

Canadian Nuclear Safety Commission

The Canadian Nuclear Safety Commission , previously known as the Atomic Energy Control Board , is best described as the governmental nuclear energy and materials watchdog in Canada....
ordered the reactor to be shut down on November 18, 2007 to facilitate repairs after safety concerns. The repairs took longer than expected and in December 2007 a critical shortage of medical isotopes occurred. The Canadian government passed emergency legislation, allowing the reactor to re-start on 16 December 2007, and production of medical isotopes to continue.^[1]

The Chalk River reactor is used to irradiate materials with neutron

Neutron

The neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton.Neutrons are usually found in atomic nucleus....
s which are produced in great quantity during the fission

Fission

Fission is a splitting of something into two parts.Fission may refer to:*In physics, nuclear fission is a process where a large atomic nucleus is split into two smaller particles....
of the U-235

U-235

U235 or U-235 may be:* German submarine U-235, a German U-boat of World War II* Uranium-235, an isotope of uraniumbang bang there goes the ship...
, which neutrons change the nucleus

Atomic nucleus

The nucleus of an atom is the very dense region, consisting of nucleons , at the center of an atom. Although the size of the nucleus varies considerably according to the mass of the atom, the size of the entire atom is comparatively constant....
of the irradiated material by adding a neutron. For example, the second most commonly used radionuclide is Tc-99m, following the most commonly used radionuclide, F-18

Fluorine-18

Fluorine-18 is a fluorine radioisotope which is an important source of positrons. It has a mass of 18.0009380 u and its half-life is 109.771 minutes....
(which is produced by accelerator bombardment of O-18

Oxygen-18

Oxygen-18 is a natural, Stable isotope isotope of oxygen and one of the environmental isotopes.18O is an important precursor for the production of fluorodeoxyglucose used in positron emission tomography ....
with proton

Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
s. The O-18 constitutes about 0.20% of ordinary oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
(mostly O-16), from which it is extracted; see FDG).

In a reactor, one of the fission products of uranium is Molybdenum-99 which is extracted and shipped to radiopharmaceutical houses all over North America

North America

North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and almost totally in the western hemisphere....
. The Mo-99 radioactively beta decay

Beta decay

In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted. In the case of electron emission, it is referred to as beta minus , while in the case of a positron emission as beta plus ....
s with a half-life

Half-life

The half-life of a quantity whose value decreases with time is the interval required for the quantity to decay to half of its initial value. The concept originated in describing how long it takes atoms to undergo radioactive decay but also applies in a wide variety of other situations....
of 2.7 days, turning initially into Tc-99m, which is then extracted (milked) from a "Moly cow" (see technetium-99m generator

Technetium-99m generator

A technetium-99m generator, or colloquially a technetium cow or moly cow, is a device used to extract the metastable isotope Technetium-99m of technetium from a source of decaying molybdenum-99....
). The Tc-99m then further decays, while inside a patient, releasing a gamma photon which is detected by the gamma camera. It decays to its ground state of Tc-99, which is relatively non-radioactive compared to Tc-99m.

Diagnostic testing

Diagnostic tests in nuclear medicine exploit the way that the body handles substances differently when there is disease or pathology present. The radionuclide introduced into the body is often chemically bound to a complex

Complex (chemistry)

In chemistry, a complex, also called a "coordination compound" or "metal complex", is a structure consisting of a central atom or molecule connected to surrounding atoms or molecules....
that acts characteristically within the body; this is commonly known as a tracer. In the presence of disease, a tracer will often be distributed around the body and/or processed differently. For example, the ligand

Ligand

In chemistry, a ligand is either an atom, ion, or molecule that bonds to a central metal, generally involving formal donation of one or more of its electrons....
methylene-diphosphonate (MDP) can be preferentially taken up by bone

Bone scan

A bone scan is a nuclear scanning test to find abnormalities in bone. It is primarily used to diagnose or help diagnose a number of conditions relating to bones, including: cancer of the bone or cancers that have spread to the bone, locating sources of bone pain and abnormal bone, diagnosing fractures that may not be seen as easily in tra...
. By chemically attaching technetium-99m to MDP, radioactivity can be transported and attached to bone via the hydroxyapatite for imaging. Any increased physiological function, such as due to a fracture in the bone, will usually mean increased concentration of the tracer. This often results in the appearance of a 'hot-spot' which is a focal increase in radio-accumulation, or a general increase in radio-accumulation throughout the physiological system. Some disease processes result in the exclusion of a tracer, resulting in the appearance of a 'cold-spot'. Many tracer complexes have been developed in order to image or treat many different organ

Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
s, gland

Gland

A gland is an Organ in an animal's body that synthesizes a substance for release such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface ....
s, and physiological processes. The types of tests can be split into two broad groups: in-vivo
In vivo

In vivo means that which takes place inside an organism. In science, in vivo refers to experimentation done in or on the living tissue of a whole, living organism as opposed to a partial or dead one or a in vitro....
and in-vitro
In vitro

In vitro refers to the technique of performing a given procedure in a controlled environment outside of a living organism. Some may argue that in vitro refers to a process that is created in a "test tube"; however, Robert Kail and John Cavanaugh on page 58 in the 4th edition of Human Development: A Life-Span View cite that in fact th...
:

Types of diagnostic studies

Common isotopes used in nuclear medicine
isotope	symbol	Z	T_1/2	decay	photons	β
Imaging:
fluorine Fluorine Fluorine is the chemical element with the symbol F and atomic number 9. Fluorine forms a single bond with itself in elemental form, resulting in the diatomic F2 molecule.... -18	¹⁸F	9	110 m	β⁺	511 (193%)	0.664 (97%)
gallium Gallium Gallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the Ga salt, in trace amounts in bauxite and zinc ores.... -67	⁶⁷Ga	31	3.26 d	ec	93 (39%), 185 (21%), 300 (17%)	-
krypton KRYPTON KRYPTON is a frame language computer programming language."An Essential Hybrid Reasoning System: Knowledge and Symbol Level Accounts of KRYPTON", R.J. Brachman et al, Proc IJCAI-85, 1985.... -81m	^81mKr	36	13.1 s	IT	190 (68%)	-
rubidium Rubidium Rubidium is a chemical element with the symbol Rb and atomic number 37. Rb is a soft, silvery-white metallic element of the alkali metal group.... -82	⁸²Rb	37	1.27 m	β⁺	511 (191%)	3.379 (95%)
technetium-99m Technetium-99m Technetium-99m is a metastable nuclear isomer of technetium-99, symbolized as 99mTc. The "m" indicates that this is a Nuclear isomer#Metastable isomers, i.e....	^99mTc	43	6.01 h	IT	140 (89%)	-
indium Indium Indium is a chemical element with chemical symbol In and atomic number 49. This rare, soft, malleable and easily Fusible alloy Post-transition metal is chemically similar to aluminium or gallium but more closely resembles zinc .... -111	¹¹¹In	49	2.80 d	ec	171 (90%), 245 (94%)	-
iodine Iodine Iodine , is a chemical element that has the symbol I and atomic number 53. Naturally-occurring iodine is a single isotope with 74 neutrons.... -123	¹²³I	53	13.3 h	ec	159 (83%)	-
xenon Xenon Xenon is a chemical element represented by the chemical symbol Xe. Its atomic number is 54. A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts.... -133	¹³³Xe	54	5.24 d	β^-	81 (31%)	0.364 (99%)
thalium-201	²⁰¹Tl	81	3.04 d	ec	69-83^* (94%), 167 (10%)	-
Therapy:
yttrium Yttrium Yttrium is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanoids and has historically been classified as a rare earth element.... -90	⁹⁰Y	39	2.67 d	β^-	-	2.280 (100%)
iodine-131 Iodine-131 Iodine-131 , also called radioiodine, is a radioisotope of iodine which has medical and pharmaceutical uses....	¹³¹I	53	8.02 d	β^-	364 (81%)	0.807 (100%)
Z = atomic number, the number of protons; T_1/2 = half-life; decay = mode of decay photons = principle photon energies in kilo-electron volts, keV, (abundance/decay) β = beta maximum energy in mega-electron volts, MeV, (abundance/decay) β⁺ = β⁺ decay Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted. In the case of electron emission, it is referred to as beta minus , while in the case of a positron emission as beta plus .... ; β^- = β^- decay Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted. In the case of electron emission, it is referred to as beta minus , while in the case of a positron emission as beta plus .... ; IT = isomeric transition Isomeric transition Isomeric transition is a radioactive decay process that occurs in an atom where the Atomic nucleus is in an excited meta state . The extra energy in the nucleus is released by the emission of a gamma ray, returning the nucleus to the ground state.... ; ec = electron capture Electron capture Electron capture is a decay mode for isotopes that will occur when there are too many protons in the atomic nucleus of an atom and insufficient energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron emission.... * X-rays from progeny, mercury Mercury (element) Mercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80. A heavy, silvery d-block metal, mercury is one of six elements that are liquid at or near room temperature and pressure.... , Hg

A typical nuclear medicine study involves administration of a radionuclide

Radionuclide

A radionuclide is an atom with an unstable Atomic nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron ....
into the body by intravenous injection in liquid or aggregate form, ingestion while combined with food, inhalation as a gas or aerosol, or rarely, injection of a radionuclide that has undergone micro-encapsulation

Micro-encapsulation

Micro-encapsulation is a process in which tiny particles or droplets are surrounded by a coating to give small capsules many useful properties. In a relatively simplistic form, a microcapsule is a small sphere with a uniform wall around it....
. Some studies require the labeling of a patient's own blood cells with a radionuclide (leukocyte scintigraphy and red blood cell

Red blood cell

Red blood cells are the most common type of blood cell and the vertebrate body's principal means of delivering oxygen to the body tissues via the blood....
scintigraphy). Most diagnostic radionuclides emit gamma ray

Gamma ray

Gamma rays are a form of electromagnetic radiation produced by atom particle interactions, such as electron-positron annihilation or radioactive decay....
s, while the cell-damaging properties of beta particles are used in therapeutic applications. Refined radionuclides for use in nuclear medicine are derived from fission

Nuclear fission

In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the atomic nucleus of an atom splits into smaller parts, often producing free neutrons and lighter atomic nucleus, which may eventually produce photons ....
or fusion processes in nuclear reactor

Nuclear reactor

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an explosion....
s, which produce radioisotopes with longer half-lives, or cyclotron

Cyclotron

A cyclotron is a type of particle accelerator. Cyclotrons accelerate charged particles using a high-frequency, alternating voltage . A perpendicular magnetic field causes the particles to spiral almost in a circle so that they re-encounter the accelerating voltage many times....
s, which produce radioisotopes with shorter half-lives, or take advantage of natural decay processes in dedicated generators, i.e. molybdenum/technetium or strontium/rubidium.

The most commonly used intravenous radionuclides are:

Technetium
Technetium

Technetium is the lightest chemical element with no stable isotope. It is a synthetic element with the atomic number 43 and is given the symbol Tc....
-99m (technetium-99m
Technetium-99m

Technetium-99m is a metastable nuclear isomer of technetium-99, symbolized as 99mTc. The "m" indicates that this is a Nuclear isomer#Metastable isomers, i.e....
)
Iodine
Iodine

Iodine , is a chemical element that has the symbol I and atomic number 53. Naturally-occurring iodine is a single isotope with 74 neutrons....
-123 and 131
Thallium
Thallium

Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray malleable poor metal resembles tin but discolors when exposed to air....
-201
Gallium
Gallium

Gallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the Ga salt, in trace amounts in bauxite and zinc ores....
-67
Fluorine
Fluorine

Fluorine is the chemical element with the symbol F and atomic number 9. Fluorine forms a single bond with itself in elemental form, resulting in the diatomic F2 molecule....
-18 Fluorodeoxyglucose
Fluorodeoxyglucose

Fluorodeoxyglucose or Fludeoxyglucose is a glucose analog . Its full chemical name is 2-fluoro-2-deoxy-D-glucose, commonly abbreviated to FDG....
Indium
Indium

Indium is a chemical element with chemical symbol In and atomic number 49. This rare, soft, malleable and easily Fusible alloy Post-transition metal is chemically similar to aluminium or gallium but more closely resembles zinc ....
-111 Labeled Leukocytes

The most commonly used gaseous/aerosol radionuclides are:

Xenon
Xenon

Xenon is a chemical element represented by the chemical symbol Xe. Its atomic number is 54. A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts....
-133
Krypton
KRYPTON

KRYPTON is a frame language computer programming language."An Essential Hybrid Reasoning System: Knowledge and Symbol Level Accounts of KRYPTON", R.J. Brachman et al, Proc IJCAI-85, 1985....
-81m
Technetium-99m
Technetium-99m DTPA

Analysis

The end result of the nuclear medicine imaging process is a "dataset" comprising one or more images. In multi-image datasets the array of images may represent a time sequence (ie. cine or movie) often called a "dynamic" dataset, a cardiac gated time sequence, or a spatial sequence where the gamma-camera is moved relative to the patient. SPECT

Single photon emission computed tomography

Single photon emission computed tomography is a nuclear medicine tomography imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera....
(single photon emission computed tomography) is the process by which images acquired from a rotating gamma-camera are reconstructed to produce an image of a "slice" through the patient at a particular position. A collection of parallel slices form a slice-stack, a three-dimensional

3D computer graphics

3D computer graphics are graphics that use a Cartesian coordinate system#Three-dimensional coordinate system representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images....
representation of the distribution of radionuclide in the patient.

The nuclear medicine computer may require millions of lines of source code to provide quantitative analysis packages for each of the specific imaging techniques available in nuclear medicine.

Time sequences can be further analysed using kinetic

Receptor-ligand kinetics

In biochemistry, receptor-ligand kinetics is a branch of chemical kinetics in which the kinetic species are defined by different non-covalent bindings and/or conformations of the molecules involved, which are denoted as receptor and ligand ....
models such as multi-compartment model

Multi-compartment model

A multi-compartment model is a type of mathematical model used to describe the way materials or energies are transmitted among the compartments of a system....
s or a Patlak plot

Patlak plot

A Patlak plot is a Graph of a function analysis technique based on the Compartment model that uses linear regression to identify and analyze pharmacokinetics problems involving irreversible uptake, such as in the case of deoxyglucose....
.

Radiation dose

A patient undergoing a nuclear medicine procedure will receive a radiation dose. Under present international guidelines it is assumed that any radiation dose, however small, presents a risk. The radiation doses delivered to a patient in a nuclear medicine investigation present a very small risk of inducing cancer. In this respect it is similar to the risk from X-ray investigations except that the dose is delivered internally rather than from an external source such as an X-ray machine.

The radiation dose from a nuclear medicine investigation is expressed as an effective dose

Effective dose

An effective dose in pharmacology is the amount of medication that produces a therapeutic response in 50% of the people taking it, sometimes also called ED-50....
with units of sievert

Sievert

The sievert is the SI derived unit of equivalent dose. It attempts to reflect the biological effects of radiation as opposed to the physical aspects, which are characterised by the absorbed dose, measured in Gray ....
s (usually given in millisieverts, mSv). The effective dose resulting from an investigation is influenced by the amount of radioactivity administered in megabecquerel

Becquerel

The becquerel is the SI derived unit of Radioactive decay. 1 Bq is defined as the activity of a quantity of radioactive material in which one atomic nucleus decays per second....
s (MBq), the physical properties

Half-life

The half-life of a quantity whose value decreases with time is the interval required for the quantity to decay to half of its initial value. The concept originated in describing how long it takes atoms to undergo radioactive decay but also applies in a wide variety of other situations....
of the radiopharmaceutical used, its distribution in the body and its rate of clearance from the body.

Effective doses can range from 6 µSv (0.006 mSv) for a 3 MBq chromium

Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is a steely-gray, Lustre , hard metal that takes a high polish and has a high melting point....
-51 EDTA measurement of glomerular filtration rate to 37 mSv for a 150 MBq thallium

Thallium

Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray malleable poor metal resembles tin but discolors when exposed to air....
-201 non-specific tumour imaging procedure. The common bone scan with 600 MBq of technetium-99m-MDP has an effective dose of 3 mSv (1).

Formerly, units of measurement were the curie

Curie

The curie is a unit of Radioactive decay, defined asThis is roughly the activity of 1 gram of the radium isotope 226Ra, a substance studied by the pioneers of radiology, Marie Curie and Pierre Curie....
(Ci), being 3.7E10 Bq, and also 1.0 grams of Radium

Radium

Radium is a radioactive chemical element which has the symbol Ra and atomic number 88. Its appearance is almost pure white, but it readily oxidizes on exposure to air, turning black....
(Ra-226); the rad

RAD

Rad may mean:* Rad , a villainous character in AC Comics's Femforce* Rad , a 1986 release about a young BMX rider* Rad , several fictional characters in the Transformers toy line...
(radiation absorbed dose), now replaced by the gray

Gray (unit)

The gray is the SI unit of absorbed dose due to ionizing radiation ....
; and the rem (Röntgen equivalent man

Röntgen equivalent man

The r?ntgen equivalent in man or rem is a unit of radiation dose. It is the product of the absorbed dose in r?ntgens and the biological efficiency of the radiation....
), now replaced with the sievert

Sievert

The sievert is the SI derived unit of equivalent dose. It attempts to reflect the biological effects of radiation as opposed to the physical aspects, which are characterised by the absorbed dose, measured in Gray ....
. The rad and rem are essentially equivalent for almost all nuclear medicine procedures, and only alpha radiation will produce a higher Rem or Sv value, due to its much higher Relative Biological Effectiveness

Relative biological effectiveness

Relative Biological Effectiveness is a health physics concept introduced in the 1950s, after it was noted that different types of radiation might affect living organisms differently....
(RBE). Alpha emitters are nowadays rarely used in nuclear medicine, but were used extensively before the advent of nuclear reactor and accelerator produced radioisotopes. The concepts involved in radiation exposure to humans is covered by the field of Health Physics

Health physics

Health physics is a field of science concerned with radiation physics and radiation biology with the goal of informing the safe use of ionizing radiation....
.

Nuclear medicine

Source of radioisotopes

Diagnostic testing

Types of diagnostic studies

Analysis

Radiation dose

Further reading

External links