Introduction to Nuclear medicine Technique

Jiraporn Sriprapaporn, M.D.

Division of Nuclear Medicine

Department of Radiology

Siriraj Hospital

Basic physics NM instrument

Radiopharm Radiion Protection

Nucl Med

Imaging

NM Imaging

•Basic physics in NM

•NM instrumentation

•Radiation protection

•Basic radiopharmaceuticals

Scope of Nuclear Medicine

Nuclear Medicine is a branch of

medicine in which radioactive materials

(unsealed source) are used for Dx & Rx

of diseases

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Diagnostic Nuclear Medicine

Rdn. Imaging Rdn. Non-imaging

• Planar • SPECT • SPECT/CT • PET • PET/CT • PET/MR

• Uptake tests • Absorption tests • WB counter • Surface counting • Breath tests

Therapeutic Nuclear Medicine

Diseases/Conditions Radionuclides used

Thyroid -Thyrotoxicosis -Thyroid cancer (DTC)

I-131

Myeloproliferative diseases -Polycythemia vera

P-32

Joint effusion -Rheumatoid Arthritis

Y-90, Sm-153 EDTMP

Bone metastases Sr-89, Sm-153 EDTMP, Re-186 HEDP

Neural crest tumors -Malignant Pheochromocytoma/ paraganglioma -Neuroblastoma -Carcinoid tummors -MTC

I-131 MIBG

Nuclear Medicine Imaging

Advantages

1. Functional 2. Sensitive, quantitative 3. Very safe 4. Low radiation (wo CT) 5. Screening & Follow up 6. Whole-body evaluation wo increased

radiation dose to the patient.

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Nuclear Medicine Imaging

Disadvantages

1. Not widely available

2. Generally nonspecific

3. Require NM instrument & radiopharmaceuticals

4. Relatively higher cost than X-ray or U/S

5. Radiation exposure to the patients

Principle of NM Imaging

• Patient

• Radiopharmaceutical

• Instrument – SPECT/CT

– PET/CT

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Principle of

Conventional NM Imaging

Radiopharmaceutical

Patient

Gamma Camera

Images

Emit gamma rays

Radiopharmaceuticals

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A radioactive material in a

form suitable for

administration to a human

for purposes of therapy or

diagnostic investigations

Radiopharmaceuticals

• Types of radiopharmaceuticals

– Radioisotopes alone

– Radioisotope-compounds

• Production of radioisotopes

– Reactor : I-131, Tc-99m

– Generator: Tc-99m

– Cyclotron: Tl-201, Ga-67, I-123

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Ideal Radionuclides for

NM Imaging

1. Low cost

2. Available

3. Pure gamma emitter

4. Optimal gamma energy

5. Optimal physical half life

6. Safe

7. Chemically active

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Route of Administration

• Injection: intravenous*, intradermal, subcutaneous, intralesional

– Bone scan, Hepatobiliary scan, etc.

• Inhalation:

– Ventilation lung scan

• Ingestion:

– GI tract study

• Instillation:

– Rdn. voiding cystography

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NM Instrument

• Planar gamma camera

• SPECT (Single Photon Emission Computed Tomography), SPECT/CT

• PET (Positron Emission Tomography), PET/CT

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Features of Radionuclide Imaging

• Safe

• Low radiation

• Functional imaging

• Quanlitative &

quantitative

• Sensitive

• Noninvasive or

minimally invasive

• Time consuming

• Requires patient

cooperation (no

patient motion)

Radionuclide Imaging

• Patient Preparation: food, water intake, drug

withdrawal, clothes, advice for the procedures etc.

• Imaging Procedures:

– Technique

– Patient Positioning

– Image Acquisition Protocol

– Data Processing

– Image Display

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Imaging Techniques

• Empty urinary bladder prior the scanning

• Avoid contamination of the radioactivity

• Avoid artifact from metallic objects

• Markers: hot, cold

• Accessories eg. treadmill, tourniquets for RNV etc.

• Choose right photopeak, appropriate collimator

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Reduced Image Quality

BL

Leakage Full Bladder

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Types of Collimator

• Parallel hole

– High energy - High resolution

– Medium energy - High sensitivity

– Low energy - General purpose

• Pin hole: for small organ details and manification

eg. hip, thyroid, vertebral body, etc

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Nuclear Medicine Imaging

• Bring the detector as close as possible

to the patient (or to the organ of

interest) !

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Image Acquisition

• Planar vs SPECT Imaging

• Static vs Dynamic Imaging

• Whole Body Imaging

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Image Acquisition

• Preset Count: static images eg. liver scan, thyroid scan

• Preset Time: static images, dynamic

study eg. vascular study, renal study

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Imaging Views

• Anterior or Posterior

• Lateral views

– Left lateral (LL)

– Right lateral (RL)

• Oblique views

– Anterior oblique (LAO, RAO)

– Posterior oblique (LPO, RPO)

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Planar Imaging

• 1 plane or 2 dimensional images (2D)

• Static, different views :

– Liver scan- ant, post, RAO, LAO, RL, LL

– Lung scan- ant, post, RPO, LPO, RL, LL

• Dynamic, 1 view :

– Vascular study

– Renal Imaging- posterior

– Hepatobiliary, GI bleeding

• WB imaging : Bone scan, I-131 TBS

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Static Images (Planar)

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Vascular Study

• Bolus Injection

– volume: small < 1 ml.

– speed: fast (large needle)

– site of injection: proximal large vein

• Dynamic study 1-3 sec/frame x 60-120 sec

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SPECT Imaging

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SPECT Imaging

• Single Photon Emission Computed

Tomography

• 3 dimensional images (3D)

• Certain regions

• 360 degree (or 180 degree for

cardiac) acquisition

• Duration of Acq - number of

detectors, organ of interest, count

rate Surface 3D

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SPECT Images

Whole-body Images

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Normal Bone Scan Bone metastases

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Image Display

• Good quality display- medium level, not too

dark or too light

• For 2 contrast areas: Use different intensity

display

• Constant format: Views, enlargement, etc

• For 2 comparative studies: Use the same

pattern

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Effect of Image Display

Thyroid Scan

Low intensity

High intensity

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Image Display

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Image Fusion

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Reduction of Radiation

(from unsealed source Rdn.)

• Shielding & avoiding contamination

• Increasing distance from the source

• Limiting time of exposure

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