Nuclear medicine and radioactivity

Nuclear Medicine – Consumer Information

Nuclear medicine and radioactivity

Nuclear medicine is a medical speciality that involves giving a patient a small amount of radioactive medication, called a radiopharmaceutical. This makes the body slightly radioactive for a short time.

A special nuclear medicine camera detects the radiation, which is emitted (released) from the body, and takes images or pictures of how the inside of the body is working. Many different organs can be imaged depending on the type of radioactive medication used.

The radioactive medication is most commonly injected into the blood stream through a vein, but might be given in different ways, including:

  • swallowed;
  • injected directly into the tissue beneath the skin;
  • injected into a shunt;
  • injected into a joint; or
  • inhaled (breathed in).

Only a very small amount of radiopharmaceutical is given to keep the radiation dose to a minimum.

Nuclear medicine can also be used to treat some diseases or conditions. In these cases, the amount of radiopharmaceutical given is much greater, and it mostly goes to the diseased or abnormal organ. The type of radiopharmaceutical given usually emits ionising radiation that has the maximum effect on the part of the body or organ system being treated.

Who are nuclear medicine specialists?

A nuclear medicine specialist is a doctor with specialised training in nuclear medicine. Some nuclear medicine specialists are also trained in medical specialities, such as radiology, cardiology (heart specialist), oncology (cancer specialist) or in the use of diagnostic ultrasound.

Who are nuclear medicine technologists?

Nuclear medicine technologists are health professionals who have obtained a university degree in nuclear medicine, which among other things qualifies them to:

  • measure and use radiopharmaceuticals;
  • give injections and take blood samples;
  • use nuclear medicine gamma cameras;
  • use computers to process and analyse nuclear medicine studies;
  • understand diseases investigated or treated by nuclear medicine; and
  • deal with patients professionally.

What is a radiopharmaceutical?

A radiopharmaceutical is a medication used in nuclear medicine that has a radioactive part and a pharmaceutical part.

The radioactive part is sometimes referred to as a radioactive label or a radioactive tracer. The radioactive part is an unstable element (radioisotope) that gives off energy as it decays (disintegrates or breaks down) and changes to a different element or energy state.

The actual amount of the radioactive substance given for most imaging tests is usually very small; approximately millionths of a gram. The dose of ionising radiation received by a patient having a nuclear medicine test can be very low or moderate; the dose varies between different types of studies.

The ionising radiation is in a similar range to that received from computed tomography (CT) imaging. The radioactive part is most commonly Technetium 99m, but other radioisotopes such as iodine 123, indium 111 and gallium 67 are also used.

Fluorine 18 is a radioisotope used in positron emission tomography (PET) imaging.

The body does not feel the ionising radiation, and it does not make you ‘warmer’ or ‘glow in the dark’. The number of times the nuclear medicine camera takes images does not determine the dose of ionising radiation received during a nuclear medicine test.

It is determined by the type and amount of radiopharmaceutical injected, the half-life of the radioisotope and how quickly this is eliminated from the body in urine, stools or breath. The half-life is the time taken for half of the radioactive atoms to decay or change their energy state.

For most radioisotopes used in nuclear medicine, this half-life is measured in hours, so after a day or so there is very little radioactivity remaining.

The pharmaceutical part can be a few atoms or a complex molecule that helps take the radioactive part to the area of the body being studied.

It is mostly the choice of the pharmaceutical part that determines where the radiopharmaceutical will go in the body and what organ system will be shown.

Technetium 99m MDP is used for a nuclear bone scan, whereas technetium 99m MAG3 is used for a nuclear renal scan.

What is a gamma camera?

A gamma camera is a machine that is able to detect and make images from the very small amounts of ionising radiation emitted from patients having a nuclear medicine study. The gamma camera usually has a table, often narrow, on which the patient lies. The images are taken using the camera ‘head’.

A camera might have one, two or occasionally three heads, with one or more being used to obtain the images. Each camera head has a flat surface that has to be very close to the patient.

The camera heads might be supported in a number of different ways using strong metal arms or a gantry.

There are no unusual sensations associated with having images taken with a gamma camera and the machine makes no noise.

How is nuclear medicine different from normal X-ray and CT examinations?

During a normal X-ray or CT examination, an image is formed from the ‘shadow’ created by the body as it is positioned between the X-ray machine (source of the X-ray beam) and the X-ray detector. The body stops some, but not all, of the X-rays and the patient is not made radioactive by the X-rays.

In nuclear medicine studies, the radiopharmaceutical given to the patient makes them, and the organ system or body part being studied, radioactive for a short time.

This ionising radiation (usually a gamma ray) is emitted or released from the body, and can be detected and measured using a nuclear medicine gamma camera.

All living things contain some radioisotopes (such as carbon 14 and potassium 40); a nuclear medicine study will make them ‘more radioactive than normal’ for a short time – hours or days.

An X-ray or CT image is formed from ionising radiation (X-rays) that passes through the body, but does not arise from the body; whereas a nuclear medicine image is formed from the ionising radiation (usually gamma rays) emitted from within the body. A gamma ray has similar properties to an X-ray, but it arises from the nucleus of an atom, whereas an X-ray arises from the electron shell of an atom.

Another way that nuclear medicine is different from X-ray and CT examinations is that an X-ray study shows what something looks . This gives indirect information about how it is working: normally, abnormally, diseased, injured and so on.

In nuclear medicine studies, the radiopharmaceutical usually only goes to the part of the body or organ system if it has some function and so shows how it is working.

The images can also give information about what the body part or organ system looks .

Nuclear medicine and X-ray tests are often complementary, providing different information that together make a diagnosis more certain.

What are the risks of a nuclear medicine study?

There are minimal risks in having a nuclear medicine study. These are allergic reactions and radiation risk.

  1. Allergic reactions have been described, but are very rare and almost always minor. If you have ever had an allergic reaction to a medication, you should tell the technologist, nurse or doctor supervising your study before you have the radiopharmaceutical. In most cases, there will be no reason to cancel the study, but you might be observed more closely during the test to ensure any reaction is treated appropriately.
  2. Radiation risk

For children and adults

  • The test involves a small dose of radiation from the radiopharmaceutical medication. The dose is similar to CT and fluoroscopy procedures. As for all imaging studies involving ionising radiation, it is important that careful consideration is given to carrying out an alternative test that does not involve ionising radiation (such as ultrasound or magnetic resonance imaging (MRI)). The radiation dose received from bone scans and renal scans is minimised by encouraging the patient to drink more clear fluid after the test. Nuclear medicine studies are used in children, and the dose of the radiopharmaceutical given is adjusted to the patient’s weight. See Radiation Risk of Medical Imaging in Adults and Children.

For pregnant women

  • Imaging of pregnant women with ionising radiation, from X-rays, CT scans and nuclear medicine studies, is generally avoided if possible. When it is required, it is usually carried out after discussion with the supervising nuclear medicine specialist. Pregnant women do sometimes have nuclear medicine studies, but this is usually only for blood clots in the lungs (pulmonary emboli (PE)). The radiation dose and associated risks of a lung scan to the patient and foetus (unborn child) are small in comparison to the risk of not diagnosing the PE. The dose given is reduced to minimise the radiation dose further. See Radiation Risk of Medical Imaging During Pregnancy.
  • For breast-feeding patients and/or those having close contact with children
  • If a person having a nuclear medicine scan is breast-feeding and has close contact with children, there could be unnecessary radiation passed on to the child. Breast-feeding and close contact might need to be restricted, depending on the radiopharmaceutical used. More specific information and restriction times can be obtained from the nuclear medicine technologist or specialist carrying out the study. The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has recommendations about breast-feeding and close contact with children after nuclear medicine tests. See nuclear medicine referrer section for further information.
  • If breast-feeding needs to be restricted, the milk can be expressed and stored (back of the fridge or frozen) for later use (after the restriction period).
  • If close contact with a child needs to be minimised, it is important to remember the emotional needs of the child. If the child needs a cuddle then this should occur. The child can be touched or kissed, but if another carer is available to comfort the child, then this would be preferable. If the child is happy and/or content, then a safe distance of 2–3 metres should be maintained between the child and the person who received the radiopharmaceutical.

What are the benefits of a Nuclear Medicine Study?

A nuclear medicine study helps your doctor evaluate how a particular area of your body or organ system is working. It can give information about how an injury, disease or infection might be affecting your body.

It can also be used to show improvement or deterioration of a known abnormality after any treatment you might have had.

Nuclear medicine studies are very good at showing how an organ system is working, and often complement other investigations and imaging studies.

*The author has no conflict of interest with this topic

Page last modified on 26/7/2017.

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Nuclear Medicine and Radiation Safety

Nuclear medicine and radioactivity

Radiation is simply a type of energy. The most familiar form of radiation is visible light, that produced from the sun or a light bulb. Other forms of radiation, such as X-rays and gamma rays, are employed in a number of beneficial applications, including medicine. 

Natural radiation exposure comes from the earth in rocks and soil and from outer space in the form of cosmic rays. A small amount of radioactive material even exists naturally in our bodies.

Every year, each person is exposed to this natural radiation and radiation from a variety of other sources, including household smoke detectors and color television sets.

Air travel increases exposure to cosmic radiation due to the higher altitudes and less atmospheric shielding.

Naturally occurring background radiation and modern activities such as watching TV and flying in an airplane all contribute to a lifetime exposure that is only slightly increased by medical imaging.

Because natural radiation is always present in everyday life, it is impossible to be totally shielded from it. On an annual basis, every person is exposed to a variable amount of radiation from natural sources, such as cosmic rays, and from industrial sources. There is no proven additional risk to human beings from background radiation exposure.

How can radiation be of value?

Radiation used for medical purposes has value for patients in diagnosing and treating disease. The treating physician should explain the benefit of a procedure and the risks associated with not undergoing the diagnostic or therapeutic procedure.

The risk is very different from one patient to another, even for the same diagnostic or therapeutic procedure, and even though the amount of exposure is the same. For example, different patients and different body parts and tissues react differently to radiation.

The same test ordered in two different patients with similar but not exactly the same disease may have a different risk profile. Age also plays a role in any risk associated with medical radiation.

Risks associated with any medical radiation exposure are a variety of factors and a medical evaluation and not on any mathematical number.

What is molecular imaging and nuclear medicine?

Molecular imaging procedures are noninvasive and very safe. More than 20 million Americans benefit each year from nuclear medicine procedures used to diagnose and treat a wide variety of diseases.

Of the molecular imaging techniques in use today, nuclear medicine procedures, such as PET scans and I-131 radiotherapy, use small amounts of radioactive materials, called radiopharmaceuticals or radiotracers, to diagnose and treat disease.

In general, the radiation risk involved in these procedures is very low compared with the potential benefits. There are no known long-term adverse side effects from diagnostic nuclear medicine procedures, which have been performed for more than 50 years. Allergic reactions may occur but are extremely rare and usually mild.

Radiopharmaceuticals are used to diagnose and treat a variety of diseases ranging from cancer and dementia, to more benign ailments such as broken bones.

Radiation exposure to patients is usually minimal for most diagnostic purposes and slightly higher for therapeutic indications.

This is because diagnostic imaging uses a low-energy isotope to see the target organ on the scan, while the therapy requires a higher energy isotope to target and kill the diseased cell.

Radiopharmaceuticals can save lives and improve a patient’s quality of life by providing diagnostic information crucial for appropriate medical care or delivering a much needed therapy. This benefit is usually discussed with the treating doctor as to how a nuclear medicine procedure can help the patient’s medical care.   

In a nuclear medicine imaging test, each radiotracer is attracted to specific organs, bones, or tissues. A special camera (PET, SPECT or gamma camera) takes pictures of the distribution of the radiopharmaceutical in the body.

The use of radiation in these procedures offers a safe and cost-effective means to provide doctors with diagnostic information that would otherwise require exploratory surgery, would necessitate more costly and invasive procedures, or would simply be unavailable.

Radiopharmaceuticals are also used for therapy, to treat overactive thyroids and some cancers.

Radiopharmaceuticals are approved by the United States Food and Drug Administration (FDA), tested carefully prior to general use and prepared with great care.

Because the amount of radiotracer used in nuclear medicine tests is extremely small, the patient’s radiation exposure is minimal.

Nuclear medicine specialists use the ALARA principle (As Low As Reasonably Achievable) to carefully select the amount of radiopharmaceutical that will provide an accurate test with the least amount of radiation exposure to the patient.

The actual dosage is determined by the patient’s body weight, the reason for the study and the body part being imaged. The targeted nature of radiopharmaceuticals allows them to be delivered mostly to the organ of interest while maintaining a low whole body radiation exposure.

How do nuclear medicine procedures compare with X-rays and CT scans?

Nuclear medicine tests and other imaging technologies differ in the way they use radiation to obtain pictures of the body.

Nuclear medicine scans detect the radiation coming from a radioactive material inside a patient’s body.

In contrast, other imaging procedures (for example, X-ray and computed tomography or CT scan) obtain images by using machines that send radiation through the body.

Nuclear medicine is also different from other imaging procedures in that it determines the presence of disease biological changes in tissue rather than changes in anatomy.

One of the most commonly used nuclear medicine exams, the PET scan, is often performed in conjunction with computed tomography (CT) because the combined images provide physicians with both functional and anatomical information on the body..

How should I prepare for a nuclear medicine procedure?

Your physician or healthcare facility should provide you with information on how to prepare for your specific nuclear medicine procedure as well as safety and home care instructions following the procedure. Patient fact sheets provide additional information on individual procedures.

Radiotracers have very short physical half-lives, which means they decay quickly into non-radioactive forms. However, radiation detection devices used at airports and federal buildings may be sensitive to the radiation levels present in patients who have recently had nuclear medicine procedures.

Are nuclear medicine studies safe for children?

Nuclear medicine studies have been performed on babies and children of all ages for more than 40 years without any known adverse effects. The functional nature of these exams and the low doses of radiation used make it a safe and effective diagnostic tool in children.

Are nuclear medicine studies safe for pregnant women?

Women who are or who might be pregnant and who are breastfeeding a child should tell their physician or technologist prior to having a nuclear medicine procedure so that medical care can be planned for both the mother and her baby.

  Some of the pharmaceuticals used in nuclear medicine procedures may pass into a breast-feeding mother’s milk and subsequently to the child.

To avoid this possibility, it is important that a nursing mother inform her physician and the nuclear medicine technologist before the examination begins.

Radiation emission guidelines

The following guidelines indicate how long patients may emit detectable radiation following treatment:

Diagnostic Tests

  • Diagnostic nuclear medicine studies are performed with Tc-99m (technetium-99m), which should not be detectable—even by sensitive radiation monitors—three or four days after a test.
  • Fluorine-18 (F-18), usually attached to glucose (FDG), is the most common radioisotope used with PET imaging; it should be undetectable one day after a test.
  • Myocardial perfusion (blood flow) imaging can be performed with technetium-99m (Tc-99m) sestamibi, technetium-99m tetrofosmin, thallium-201 (Tl-201) or a combination of both. While Tc-99m is undetectable after only a few days, Tl-201 may remain detectable for 30 days.
  • Gallium-68, usually attached to octreotide (DOTATATE), is a PET imaging radioisotope. It should be undetectable one day after a test.

Treatment or Therapy

  • Radiodine-131 (sodium I-131), used to treat hyperthyroidism, thyroid cancer and lymphoma, may remain detectable for as long as three months after treatment. More information on I-131 treatment is available at and
  • Octreotide radiolabelled with Lutetium-177 (177Lu-DOTATATE) is used to treat neuroendocrine tumors. Usually, the amount of emitted radiation is low. However, it may be detectable for few weeks.

Patients who plan to travel following a nuclear medicine procedure should carry a letter of explanation from their doctor that includes the patient’s name, contact information for the testing facility, the name of the nuclear medicine procedure, the date of the treatment or test, the radionuclide that was used, its half-life, its administered activity and 24-hour contact information.

Nuclear medicine procedures expose children to a very small amount of radiation that is within the lower range of what is received from routine diagnostic imaging procedures using X-rays. The specific amount of radiation exposure varies depending on the type of study.

Questions to ask your Doctor

  • What is this test looking at?
  • How will the results be used?
  • How will this test help you help me?

Remember to always discuss your medical care with your doctor.


Nuclear Medicine

Nuclear medicine and radioactivity

The use of radioisotopes in medicine has enabled us to acquire a greater understanding of the inner functionning of our body. The visualisation techniques that are now common in diagnostic medicine have given us both a more extensive knowledge and a more effective capacity to heal.

For the diagnosis, thanks to the injection of the radioactive tracer in vivo, the nuclear physician can access a functional and metabolic imaging. This allows the detection of the serious lesions, the monitoring of their evolution as well as the follow-up of the surgical interventions when necessary.

Two existing techniques are gamma scintigraphy and positron emission tomography.

In the field of therapy, the radioactive product can destroy cancer cells by igenerating high doses of radiation. Thanks to the targeted injection of radiopharmaceutical drugs, it is possible to treat, for example, certain cancers such as hyperthyroidism and synovitis.

In 2016 the number of people using nuclear medicine was estimated to 35 million, either for a diagnosis or for a therapy. The demand for radioisotopes for these diagnoses and therapies is increasing worldwide, both in developed and fast-developing countries China and India.

In 2017, France had 750 specialist doctors in more than 200 nuclear medicine centers. The number of diagnoses made, mainly scintigraphies, was 1.5 million, an increase of 9% per year.

Exploring the brainScintigraphy is one of the most commonly used techniques in understanding the way the body works, and providing diagnostics when it doesn’t. The level of the radioactive tracer present in the brain is directly proportional to the rate of blood flow: at a maximum in the most active parts of the brain (coloured in red). This comparison of brain ‘slices’ for a healthy person and an Alzheimer victim helps to highlight the affected areas, showing that the greater damage is done in the more active sections of the brain

André Aurengo, Hôpital Pitié-Salpétrière

The ‘tracer method’ – a crucial component of the above-mentioned techniques – was first developed by Georg von Hevesy in 1923.

It was not until 1934, however, when Irene and Frederic Joliot-Curie pioneered the creation of artificial radioactive isotopes, that doctors and biologists were first able to use the tracer method in making their diagnoses.

Advances made over the last eighty years have meant that much weaker forms of radiation, which make for more accurate and delicate scans, can also easily be detected. This means that radioactive sources can now be taken into the body without damaging the healthy tissue.

As a result, doctors can have patients ingest specific radioactive samples which will either follow certain processes in the body or attach themselves to certain organs. The radiation these sources emit can then be analyzed to reveal information about the way the body works: such elements are known as radioactive or radiopharmaceutical ‘tracers’.

Towards the end of the 1940’s, iodine 131 was first used as a radioactive tracer. The body tendency to absorb iodine into the thyroid gland made iodine 131 an excellent tracer for thyroid cancer, and marked an important milestone in the history of radioactivity in medicine.

The real-life applications of the tracer method are numerous and varied: phosphates marked with technetium 99 are used in bone tissue scans, myocardial scintigraphs are carried out with thallium 201, thyroid scintigraphy involves iodine 123 and lung scans frequently use krypton 81. These scans, often carried out with gamma cameras, provide information that is invaluable to doctors in choosing the appropriate therapies.

In order to make a safe and efficient scan of the brain, lighter radioactive tracers need to be used. The use of positron emitters (oxygen, fluorine…

) in positron emission tomography (or PET scanning) allows for the specific targeting of lighter molecules to serve as tracers.

This technique has truly revolutionized oncology by allowing for the identification of tumours at a much earlier stage than was previously achievable.

The applications of radioisotopes are not just limited to imaging, however. Beta emitters are frequently used for therapeutic purposes, for both curative and palliative ends (metabolic radiotherapy is a good example of the latter).

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Learn more :

Gamma Cameras

Positron Emission Tomography


Nuclear Medicine Procedures

Nuclear medicine and radioactivity

Nuclear medicine procedures are used in diagnosing and treating certain illnesses. These procedures use radioactive materials called radiopharmaceuticals. Examples of diseases treated with nuclear medicine procedures are hyperthyroidism, thyroid cancer, lymphomas, and bone pain from some types of cancer.

The amount of radioactive materials used in diagnosing illnesses depends on the needs of the person and range from a small amount to a large amount.

These materials flow through different body organs and in some cases are taken up by specific organs or tissue.

The radiation that comes from the radiopharmaceutical is used for treatment or is detected by a camera to take pictures of the corresponding body organ, region or tissue.

What happens during a nuclear medicine imaging procedure?

  • During a nuclear medicine imaging procedure, doctors give patients radiopharmaceuticals. Depending on the type of medical examination they can be breathed in (inhaled), injected, or swallowed.
  • Once the radiopharmaceutical is given, the patient is usually asked to lie down on a table. A special camera that detects radiation is placed over the patient’s body to take pictures. A computer is used to show where the body concentrates the radioactive material. This allows doctors to check if organs are working properly and diagnose diseases.
  • The radioactive materials usually leave the body within hours to months.

What are radioactive materials?

Radioactive materials are chemicals that release radiation (energy). Radioactive materials can be natural or they can be man-made. They can be solids ( some rocks on earth) or liquids or they can also be gases that people can breathe ( radon). Each radioactive material has a unique half-life, which tells how quickly it stops being radioactive.

Are any health effects associated with nuclear medicine procedures?

The Nuclear Regulatory Commission (NRC), the U.S. Food and Drug Administration (FDA) and states regulate the use of radioactive materials for nuclear medicine to make sure patients, medical personnel, and the public are safe. Before any type of nuclear medicine procedure is used, it must be justified to ensure the benefits of the procedures outweigh risks to the patient.

However, exposure to too much radiation can quickly damage organs or tissues, while exposure to any amount of radiation might lead to an increase in the risk of cancer years after the exposure occurs. Image Gentlyexternal icon is a campaign that encourages medical facilities to use a “child size” amount of radioactive material when a child has a nuclear medicine procedure.

What are some common nuclear medicine procedures?

There are several nuclear medicine procedures for diagnosing illnesses and treating diseases.

Some common procedures are as follows:

Diagnostic Procedures

  • Heart disease can be diagnosed with a stress test using Sestamibi that contains technetium-99m or through the use of positron emission tomography (PET) scans. See more information about how PET scans are used in nuclear medicine in the section below.
  • Gallbladder problems can be diagnosed using hepatobiliary iminodiacetic acid (HIDA) scans that contain a radioactive material tracer, usually technetium-99m.
  • Thyroid disease can be diagnosed with a radioactive iodine thyroid scan that utilizes sodium iodine which contains iodine-131.

How are PET scans used?

Doctors use PET scans to get more data about how body organs are functioning. PET scans may be performed together with a computerized axial tomography (CAT) scan that provides an image of the organ.

PET scans provide a clear view of how the organs are working at the cellular level and if they have been damaged. The scan helps doctors determine effective treatment options.

PET scans are commonly used to diagnose heart conditions, help doctors determine appropriate cancer treatment, help in diagnosing Alzheimer’s disease and brain disorders. They also can provide data for medical research.


How are nuclear medicine scans done?

As stated above, nuclear medicine scans may be performed on many organs and tissues of the body. Each type of scan employs certain technology, radionuclides, and procedures.

A nuclear medicine scan consists of 3 phases: tracer (radionuclide) administration, taking images, and image interpretation.

The amount of time between administration of the tracer and the taking of the images may range from a few moments to a few days. The time depends on the body tissue being examined and the tracer being used.

Some scans are completed in minutes, while others may need the patient to return a few times over the course of several days.

One of the most commonly performed nuclear medicine exams is a heart scan. Myocardial perfusion scans and radionuclide angiography scans are the 2 primary heart scans. In order to give an example of how nuclear medicine scans are done, the process for a resting radionuclide angiogram (RNA) scan is presented below.

Although each facility may have specific protocols in place, generally, a resting RNA follows this process:

  1. The patient will be asked to remove any jewelry or other objects that may interfere with the procedure.

  2. If the patient is asked to remove clothing, he or she will be given a gown to wear.

  3. An intravenous (IV) line will be started in the hand or arm.

  4. The patient will be connected to an electrocardiogram (ECG) machine with electrodes (leads) and a blood pressure cuff will be attached to the arm.

  5. The patient will lie flat on a table in the procedure room.

  6. The radionuclide will be injected into the vein to “tag” the red blood cells. Alternatively, a small amount of blood will be withdrawn from the vein so that it can be with the radionuclide. The radionuclide will be added to the blood and will be absorbed into the red blood cells.

  7. After the tagging procedure, the blood will be returned into the vein through the IV tube. The progress of the red blood cells through the heart will be traced with a scanner.

  8. During the procedure, it will be very important to lie as still as possible. Any movement can adversely affect the quality of the scan.

  9. The gamma camera will be positioned over the patient as he or she lies on the table, and will obtain images of the heart as it pumps the blood through the body.

  10. The patient may be asked to change positions during the test. However, once the position has been changed, the patient will need to lie still without talking.

  11. After the scan is complete, the IV line will be discontinued. The patient will be allowed to leave, unless the healthcare provider gives different instructions.


What is nuclear medicine? In diagnosis, in treatment, and more

Nuclear medicine and radioactivity

Radiation is used in nuclear medicine and radiology. In nuclear medicine, radioactive materials known as radioisotopes, or radiopharmaceuticals, are introduced into the body. In radiology, X-rays enter the body from outside.

According to the Center for Nuclear Science and Technology Information, about one-third of all procedures used in modern hospitals involve radiation or radioactivity. The procedures offered are effective, safe, and painless and they do not need anesthesia.

Nuclear medicine is used to diagnose a wide range of conditions.

The patient will inhale, swallow, or be injected with a radiopharmaceutical. This is a radioactive material. After taking the substance, the patient will normally lie down on a table, while a camera takes pictures.

The camera will focus on the area where the radioactive material is concentrated, and this will show the doctor what kind of a problem there is, and where it is.

Types of imaging techniques include positon emission tomography (PET) and single-photon emission computed tomography (SPECT).

PET and SPECT scans can provide detailed information about how a body organ is functioning.

This type of imaging is particularly helpful for diagnosing thyroid disease, gall bladder disease, heart conditions, and cancer. It can also help diagnose Alzheimer’s disease and other types of dementia and brain conditions.

In the past, diagnosing internal problems often needed surgery, but nuclear medicine makes this unnecessary.

After diagnosis, and when treatment starts, PET and SPECT can show how well the treatment is working.

PET and SPECT are also offering new insights into psychiatric conditions, neurological disorders, and addiction.

Other types of imaging involved in nuclear medicine include targeted molecular ultrasound, which is useful in detecting different kinds of cancer and highlighting blood flow; and magnetic resonance sonography, which has a role in diagnosing cancer and metabolic disorders.

Share on PinterestRadioactive agents my be swallowed in pill form, inhaled, or injected as part of a person’s treatment.

Radioactive techniques are also used in treatment. The same agents that are used in nuclear imaging can be used to deliver treatment. The radiopharmaceutical can be swallowed, injected, or inhaled.

One example is radioactive iodine (I-131). It has been used for over 50 years to treat thyroid cancer and hyperthyroidism, or an overactive thyroid. Now, it is also used to treat non-Hodgkin lymphoma and bone pain from some kinds of cancer.

Iodine-131 (I-131) targeted radionuclide therapy (TRT) introduces radioactive iodine into the body. As the thyroid cells or cancer cells absorb this substance, it kills them. I-131 can be given as capsules or in liquid form.

In the future, it may be possible to embed chemotherapy into medication imaging agents that will attach only to cancer cells. In this way, the chemotherapy would kill only the target cells and not the nearby healthy tissue. This would reduce some of the adverse effects of chemotherapy.

Radioimmunotherapy (RIT) combines nuclear medicine (radiation therapy) with immunotherapy. Immunotherapy is a treatment that mimics cellular activity in the body. Combining the two types of treatment means the nuclear medicine can be targeted more directly to the cells that need it.

Various radionuclides are used. The most common one is I-131, or radioactive iodine therapy (RAI). Other options include 90Y-ibritumomab tiuxetan, or Zevalin, which is used to treat different types of lymphoma. 131-I-tositumomab, or Bexxar, is used to treat lymphoma and multiple myeloma.

Experts in nanotechnology, advanced polymer chemistry, molecular biology, and biomedical engineering are investigating ways to deliver the drugs to the correct site without affecting surrounding tissues.

Theranostics is an approach that integrates nuclear medicine techniques for diagnosis and imaging with those for treatment. By combining molecular targeting vectors, such as peptides, with radionuclides, it can direct the radioactive substance to the target area to diagnose and deliver treatment at the same time.

A person who is going for diagnosis or treatment with nuclear medicine should be sure to inform the health professional if they are pregnant or breastfeeding, or if they may be pregnant.

Nuclear imaging

The patient may have to wear a gown, or they may be able to wear their own clothes, but they will have to remove jewelry and other metal-base accessories.


Share on PinterestAfter having radioactive treatment, a person should avoid physical contact with other people as much as possible for 2-5 days, which may involve taking time off work.

When a patient has treatment for the thyroid with I-131, no special equipment is used.

A single, prepared dose will be taken by mouth. This is a one-time treatment.

The patient should not eat or drink after midnight on the day of the treatment. If the treatment is for a thyroid problem, the doctor will normally advise them to stop taking their regular thyroid medication between 3 and 7 days before the treatment.

The patient may be able to return home after the dose, or they may have to stay overnight in the hospital.

However, because the body will not absorb all the radioactive iodine, it will continue to leave the body over the next 2 to 5 days.

The individual should avoid contact with other people as far as possible, and especially with infants and pregnant women.

This may mean taking time off work. They should also prepare their own food, avoid sleeping with another person, flush the lavatory twice after use, and wash their clothes and laundry separately.

Most of the iodine will leave the body through the urine, but it is also excreted through tears, sweat, saliva, vaginal discharge, and feces.

Women are advised to avoid becoming pregnant for 6 to 12 months following treatment.

Anyone who plans to travel immediately after treatment should get a letter from the doctor, as radioactivity may show up on scanning machines at airports.

Too much radiation can potentially damage organs or tissues or increase the risk of cancer.

However, when used for diagnosis, the level of radiation exposure is around the same as a person receives during a routine chest x-ray or a CT scan. As a result, nuclear medicine and imaging procedures are considered non-invasive and relatively safe. Their effectiveness in diagnosing disease means that the benefits normally outweigh the risks.

Treatment with nuclear medicine involves larger doses of radioactive material.

For example, a nuclear medicine lung scan would expose a person to 2 millisieverts (mSv) of radioactivity, while cancer treatment would expose a tumor to 50,000 mSv.

This additional dose may affect the patient, and side effects are possible.

However, since the treatment often targets potentially fatal diseases, the benefits tend to outweigh the risks.

As technology advances, scientists hope that treatments will be more directed toward the tumor or disease, and less ly to affect the person as a whole.

The Nuclear Regulatory Commission (NRC) and the U.S. Food and Drug Administration (FDA) closely regulate the use of radioactive materials for nuclear medicine to ensure the safety of patients.