Overview

Nuclear Medicine is a specialised medical field that uses small amounts of radioactive materials, called radiotracers or radiopharmaceuticals, to diagnose and treat disease. Unlike many imaging tests that mainly show body structure, Nuclear Medicine shows how organs and tissues are functioning at a cellular or molecular level.

It is commonly used in cancer care, heart disease, thyroid disorders, bone disease, kidney function assessment, infection imaging, neurological conditions, and selected targeted therapies.

What Is Nuclear Medicine?

Nuclear Medicine involves giving a radiotracer through injection, swallowing, or inhalation, depending on the test or treatment. The radiotracer travels to a specific organ, tissue, or disease target. Special cameras then detect the radiation signal and create images that help doctors understand body function.

Common areas of care include:

• PET/CT imaging

• SPECT/CT imaging

• Gamma camera scans

• Bone scan

• Thyroid scan and radioiodine therapy

• Renal scan

• Nuclear cardiology and myocardial perfusion imaging

• Infection and inflammation imaging

• Cancer staging and treatment response assessment

• Neuroendocrine tumour imaging and therapy

• PSMA PET and radioligand therapy for selected prostate cancer cases

• Theranostics and personalised radionuclide therapy

The goal is to support early diagnosis, accurate staging, targeted treatment, and safe follow-up.

Causes and Risk Factors

Nuclear Medicine may be recommended when doctors need functional information about an organ, cancer, blood flow, metabolism, or treatment response.

Common reasons for referral include:

• Cancer diagnosis, staging, recurrence, or treatment monitoring

• Chest pain or suspected reduced blood flow to the heart

• Thyroid disease or thyroid cancer

• Bone pain, fracture, infection, or suspected metastasis

• Kidney drainage or function assessment

• Unexplained fever or suspected infection

• Neuroendocrine tumours

• Advanced prostate cancer evaluation

• Brain disorders in selected cases

• Planning for radiopharmaceutical therapy

Special precautions may be needed for children, pregnant patients, breastfeeding mothers, patients with kidney disease, and those receiving therapeutic radioactive medicines.

Symptoms

Nuclear Medicine is usually advised based on a diagnosis, abnormal test result, or clinical suspicion rather than symptoms alone.

Symptoms that may lead to Nuclear Medicine evaluation include:

• Chest pain or breathlessness on exertion

• Unexplained bone pain

• Cancer-related symptoms or rising tumour markers

• Neck swelling or thyroid-related symptoms

• Recurrent fever without clear source

• Urinary obstruction or kidney-related concerns

• Unexplained weight loss

• Persistent pain after cancer treatment

• Symptoms suggesting disease recurrence

Emergency care is needed for severe chest pain, sudden breathlessness, fainting, severe weakness, seizures, or rapidly worsening health.

Diagnosis

Diagnosis depends on the type of scan and the organ or disease being evaluated. The nuclear medicine physician selects the appropriate radiotracer and imaging method.

Common diagnostic methods include:

• PET/CT for cancer staging, recurrence, and treatment response

• SPECT/CT for functional and anatomical correlation

• Bone scan for bone metastasis, infection, or occult injury

• Myocardial perfusion imaging for heart blood-flow assessment

• Thyroid uptake and scan

• Renal dynamic scan for kidney function and drainage

• Hepatobiliary scan for selected gallbladder or bile-flow conditions

• Sentinel lymph node mapping in selected cancer surgeries

• Infection or inflammation scans in selected cases

Patients may need preparation such as fasting, hydration, avoiding certain medicines, or checking blood sugar before specific scans.

Treatment Options

Nuclear Medicine also provides targeted treatment using therapeutic radiopharmaceuticals. These treatments deliver radiation to specific cells or tissues while limiting exposure to surrounding healthy tissue as much as possible.

Treatment options may include:

• Radioiodine therapy for selected thyroid disorders and thyroid cancer

• Peptide receptor radionuclide therapy for selected neuroendocrine tumours

• PSMA-targeted radioligand therapy for selected advanced prostate cancer cases

• Bone-targeted radiopharmaceutical therapy for selected painful bone metastases

• Theranostics, where imaging confirms the disease target before treatment

• Dosimetry and safety planning in selected therapies

• Post-therapy scans and follow-up blood tests

After therapy, patients receive radiation safety instructions about distance, hygiene, travel, and contact with children or pregnant people based on the treatment used.

Prevention and Outlook

Nuclear Medicine does not prevent disease by itself, but it helps detect disease earlier, assess severity, guide treatment, and monitor response accurately. Radiotracer doses are carefully selected so that imaging provides useful information with the lowest practical radiation exposure.

The outlook depends on the underlying condition. In many diseases, Nuclear Medicine improves clinical decision-making by showing whether disease is active, where it is located, and whether treatment is working. In selected cancers and thyroid conditions, radiopharmaceutical therapy can also become an important part of treatment.

Frequently Asked Questions

1. Is Nuclear Medicine safe?
   Yes. Nuclear Medicine tests are generally safe when clinically appropriate. Diagnostic scans use small amounts of radiotracer, and radiation exposure is carefully controlled.

2. How is Nuclear Medicine different from CT or MRI?
   CT and MRI mainly show structure. Nuclear Medicine shows body function, metabolism, blood flow, or molecular activity. PET/CT and SPECT/CT combine functional and anatomical information.

3. Will I be radioactive after the scan?
   For a short time, yes, but most diagnostic radiotracers leave the body or decay quickly. Drinking fluids may help clear some tracers faster, if advised.

4. Can pregnant or breastfeeding patients have Nuclear Medicine tests?
   They should inform the care team before the test. Some scans may be postponed, modified, or require special breastfeeding instructions.

5. What is a PET/CT scan?
   PET/CT combines a PET scan, which shows metabolic or molecular activity, with CT images that show body structure.

6. What is theranostics in Nuclear Medicine?
   Theranostics combines targeted imaging and targeted treatment. A diagnostic scan first checks whether the disease has the right target, and then a related therapeutic radiopharmaceutical may be used.