Nuclear Medicine- FINALS L9

NUCLEAR MEDICINE

• Specialized area of radiology

• Radiology (does x-ray)

• Uses radioactive material or radiopharmaceuticals (or radionuclei) to examine a body organ’s function & structure

  • Administered through injection, inhalation, ingestion

  • Can be used for therapeutic procedures

  • Treat cancers in early onset o treat thyroid diseases (goiter; hyper/hypo thyroidism)

• Treat abnormalities very early in the progression of a disease

RADIOLOGY

• Gives information about anatomy

• Radiation source is from outside patient’s body

NUCLEAR MEDICINE

• Gives information about physiology

• Radiation source goes inside patient’s body (use gamma camera to detect radionuclei inside the body)

NUCLEAR MEDICINE TECHNOLOGIST

• a.k.a Nuclear Medical Technologist

• Prepare & administer radionuclide to patient

• Perform imaging procedure (diagnostic) & could also involve in radiation therapy (therapeutic)

RADIATION

• Describes any process in which energy travels through a vacuum or through a medium, ultimately to be absorbed by another body

• Also used to refer energy itself that’s radiated

• Has two types

  • Ionizing radiation (used in nuclear medicine)

  • Non-ionizing radiation

IONIZING RADIATION

• High frequency

• Radiation of sufficient energy to disrupt DNA strands

• Consists of subatomic particles

• Naturally occurring

• Medical purposes

• Artificial

IONIZING RADIATION PARTICLES

• Alpha

• Beta

• Neutrons

ELECTROMANGETIC WAVES

Gamma rays

ALPHA PARTICLES

• Can’t penetrate the skin

• Stopped by a sheet of paper or outer layer of skin

• Therapeutic

EXAMPLES OF ALPHA PARTICLES

• Americium (241Am)

• Radium (226Ra)

• Thorium (228Th)

BETA PARTICLES

• Can penetrate the skin tissues

• Stopped by a layer of clothing or by few millimeters of substance

• Responsible for therapeutics uses of nuclear medicine

• Most commonly used for therapeutic medicine

EXAMPLES OF BETA PARTICLES

• Hydrogen (3H)

• Carbon (14C)

• Strontium (90Sr)

EXAMPLES OF NEUTRONS

• Californium (252Cf)

• Plutonium (239Pu)

GAMMA RAYS (EW)

• Highly penetrating

• Used with a shield

• For diagnostic procedure

EXAMPLES OF GAMMA RAYS (EW)

• Cesium (137Cs)

• Cobalt (60Co)

• Iridium (192Ir)

RADIOACTIVE TRACER (RADIOTRACER)

• Chemical compounds in which one or more atom have been replaced by a radioisotope

• Monitoring the radioactive decay of radioactive tracers enables to see chemical reactions inside the body (see body organ’s function)

EXAMPLES OF RADIOTRACER

• Tc-99m PO4 (technetium pertechnetate)

• Tc-99m HDP (hydroxydiphosphonate)

• Iodine 131

• Tc-99m Sestamibi

GAMMA CAMERA

• Doesn't contain radiation (only detects what’s inside the organ)

• Main nuclear medicine equipment

• Radiation is inside the patient’s body

  • Example: cardiac scan

COLLIMATOR

The “lens” of the gamma camera

COMMON NUCLEAR MEDICINE DIAGNOSTIC PROCEDURE

• Thyroid Scan

• Whole Body Iodine Scan

• Bone Scan

• Myocardial Perfusion Imaging

• Positron Emission Tomography (PET)

• Scintimammography

• Renal Scintigraphy

• Hepatobiliary Scan (HIDA)

• Lung Perfusion Scan

THYROID SCAN

• One of the most common requested procedures

• Used to evaluate thyroid function or to better evaluate thyroid nodule or mass

• Image with 131I or Tc-99m pertechnetate

• Assess the size of the thyroid gland

  • 4x2 cm (normal size of thyroid gland)

  • 2 lobes connected by an isthmus

• Only scan where it can assess if nodule of interest is hot or cold

WHOLE BODY IODINE SCAN

• Staging of thyroid cancer

• Detect presence of metastasis specific for thyroid cancer

BONE SCINTIGRAPHY/ SCAN

• Uses Tc-99m MDP/HDP

• Useful in oncology planning & management

• 5% bone turnover (process of resorption followed by replacement of a new bone with little change in shape) can be detected by bone scan while 50% minimum mineral loss is required before lesion is visualized on radiographs

COMMON PRIMARY CANCERS THAT METASTASIZE TO THE BONE (PBKTL)

• Breast CA 50-85% (as of October 2012, is the most prevalent cancer in the country)

• Kidney 80%

• Prostate 50-75%

• Hodgkin Lymphoma 50-75%

• Lung Carcinoma 30-50%

• Thyroid CA 40%

MYOCARDIAL PERFUSION IMAGING

• Detect & diagnose CAD

• Assess functional significance of known CAD

• “The risk of cardiac death & myocardial infarction in a patient with a normal stress perfusion study is <1% annually”

MYOCARDIAL VIABILITY STUDY

• Myocardial ischemia

• Myocardial Infarction

MYOCARDIAL ISCHEMIA

• Narrowing of blood vessels (high BP)

• Nuclear medicine role in providing information of the benefit from cardiac bypass (applies new vessel) or stenting (applies metal-like; foil)

• Acute, recent (can still undergo surgeries)

MYOCARDIAL INFARCTION

• Particular area in myocardium that had been already compromised with circulation for sometime

• Area is usually not viable

• No longer benefit from cardiac bypass or stenting

POSITRON EMISSION TOMOGRAPHY (PET)

• Establish if patient is responsive to chemotherapy

• Established possibility of tumor especially in areas difficult to access

• Can used as screening tool & monitoring tool

• Done before & after chemotherapy (if there are changes in cancer cells)

• Assess different tissue metabolism & function

QUESTION PET CAN ANSWER

1. Where is the tumor?

2. Is it benign or malignant?

3. What is the extent of the disease?

4. Is the treatment working?

5. Has the cancer recurred?

PET / CT

• Combination of CT scanning & PET

• Better localization of lesions

SCINTIMAMMOGRAPHY

• Uses Tc-99m Sestamibi to detect cancer cells in the breast & axillary area (near the armpits)

• Used in patients with abnormal mammograms, dense breasts, & post-operatively (monitoring)

RENAL SCINTIGRAPHY

• Evaluate perfusion, cortical, & excretory functions

• Used also to evaluate functional transplanted kidney

HEPATOBILIARY SCAN (HIDA)

• Hepatobiliary iminodiacetic acid (HIDA) scan

• Help diagnose acute & chronic cholecystitis, biliary atresia

• Provide information on post-surgical bile drainage & biliary leakage

LUNG PERFUSION SCAN

• Detection of pulmonary embolism (blood clot in lungs)

• V/Q scan & Pulmonary embolism

  • Identify ventilation-perfusion mismatch

  • Give heparin (management; to dissolve clots)

COMMON NUCLEAR MEDICINE THERAPEUTIC PROCEDURES

Radionuclide Therapies

RADIONUCLIDE THERAPIES

Uses beta particle

RADIOACTIVE IODINE TREATMENT FOR THYROID DISEASES

• Usually taken via oral route

• Absorbed from GIT

• Iodine goes directly to thyroid tissue

• Radioactive iodine starts to emit beta particles from mm to cm

• Thyroid gland shrinks & normalize

HYPERTHYROIDISM / DIFFERENT THYROID CANCER

If primary cancer from thyroid gland metastasizes, iodine will spread to the part where there are thyroid gland metastatic lesions to stop the spread