RADIATION PROTECTION IN NUCLEAR MEDICINE

International Atomic Energy Agency

RADIATION PROTECTION IN NUCLEAR MEDICINE

Part 0: Introduction to Nuclear Medicine

Nuclear Medicine Part 0. Introduction to Nuclear Medicine 2

Clinical Problem

Radiopharmaceutical Instrumentation

Diagnosis and Therapy withUnsealed Sources

Nuclear Medicine


Radionuclide Pharmaceutical Organ Parameter + Colloid Liver RE

Tc-99m + MAA Lungs Regional perfusion

+ DTPA Kidneys Kidney function

I-123 NaI Thyroid Uptake/ I-131 NaI Thyroid Therapy

F-18 FDG Whole Body Tumor Localization

Radiopharmaceuticals


1896 Natural Radioactivity Becquerel1898 Radium Curie1911 Atomic Nucleus Rutherford1913 Model of the atom Bohr1930 Cyclotron Lawrence1932 Neutron Chadwick1934 Artificial Radionuclide Joliot-Curie1938 Production and Identification of I-131 Fermi et al 1942 Nuclear Reactor Fermi et al1946 Radionuclides Commercially Available Harwell1962 Tc-99m in Nuclear Medicine Harper1970s F18-FDG for PET Imaging Ido & Wolfe

History- Radionuclides


Henri Becquerel Ernest Rutherford Maria Curie

Frederique Joliot-Irene Curie

Pioneers


Radiopharmaceutical For treatment of Route of Maximumadministration activity

I-131 iodide Thyrotoxicosis Oral 1 GBqI-131 iodide Carcinoma of thyroid Oral 20 GBqI-131 MIBG Malignancy IV 10 GBqP-32 phosphate Polycythaemia vera IV or oral 200 MBqSr-89 chloride Bone metastases IV 150 MBqY-90 colloid Arthritic conditions/ Intra-articular 250 MBq

malignant effusions Intra-cavitary 5 GBq Y-90 spheres Hepatocellular Carcinoma Intra-articular 100 MBqEr-169 colloid Arthritic conditions Intra-articular 50 MBqRe-186 colloid Arthritic conditions Intra-articular 150 MBq

Current Methods-Therapy


1936 Therapeutic use of Na-24 (leukemia) Hamilton et al1936 Therapeutic use of P-32 (leukemia and Lawrence

polycythemia vera)1941 Therapeutic use of iodine in hyperthyroidism Hertz et al1942 Therapeutic use of iodine in treatment of

metastasis from thyroid cancer1945 Therapeutic use of Au-198 in treatment of Muller

malignant effusion1958 Treatment of bone metastasis with P-32 Maxfield1963 Medical synovectomy using Au-198 Ansell

History-Therapy


The absorbed dose to be delivered should be determinedfrom uptake measurements, effective half-life of the radio-pharmaceutical and the size of the thyroid.

The radiopharmaceutical is administered p.o.

Hyperthyroidism

Cured after Hypothyroidism3-4 months 1 year after <7 years after >7 years 85% 98% 14.8% 27.9%

I-131 Therapy


Radiosynovectomy


Pain Palliation

Intravenous injection ofa radiopharmaceutical whichincludes e.g. Sr-89 or Sm-153


Number of Patients per million population

Thyroid Malignancy: 1950.1Hyperthyroidism: 4616.6Polycythemia vera: 168.1Bone Metasstases: 316.5Synovitis: 380.6Others: 120.5Total 7552.4

Annual Numbers of Therapies with Radiopharmaceuticals in all Health-care

Levels(As per UNSCEAR Report 2008)


• Imaging (Planer/SPECT and PET Cameras)Bone, Brain, Lungs , Thyroid, Kidneys, Liver/Spleen, Cardiovascular, Stomach/GI-tract, Tumours, Whole Body, Abscesses ….• Non-imaging (probes)Thyroid uptake, Renography, Cardiac Output, Bile Acid Resorption….• Laboratory testsGFR, ERPF, Red Cell Volume/Survival, AbsorptionStudies (B12, iron, fat), Blood Volume, Exchange-able Electrolytes, Body Water, Bone Metabolism…..• Radioimmunoassays (RIA)• Radionuclide guided Surgery

Current Diagnostic Methods


Annual Frequencies of Diagnostic Examinations

(As per UNSCEAR Report 2008)

Nuclear Medicine

Nuclear Medicine Examinations in Different Health Care Levels

(As per UNSCEAR Report 2008)

Part 0. Introduction to Nuclear Medicine 14

Nuclear Medicine

Annual Number and Collective Effective Radiation Dose from Diagnostic Nuclear Medicine

Examinations(As per UNSCEAR Report 2008)



1927 Blood flow studies (Bi-214) Blumgart-Weiss1935 Bone metabolism (P-32) Chiewitz-de Hevesy1939 Thyroid studies (I-131) Hamilton et al1948 Radiocardiography (Na-24) Prinzmetal et al1956 Renography (I-131) Taplin, Winter1957 Liver scan (Au-198 colloid) Friedell et al1961 Bone scan (Sr-85) Fleming et al1962 Myocardium (Rb-86, Cs-131) Carr et al1964 Lung scan Taplin et al1965 Brain scan (Tc99m-pertechnetate) Bollinger et al1971 Bone scan (Tc99m-complex) Subramanian et al1970s F18-FDG for PET Imaging Ido & Wolfe

History-Diagnostics


de Hevesy G & Paneth F. Die Lösligkeit des Bleisulfids und Bleichromats.Z. Anorg Chem 82, 323, 1913.

de Hevesy G. III. The absorption and translocation of lead by plants.Biochem J, 17, 439, 1923.

Chiewitz O. & de Hevesy G.Radioactive indicators in the studyof phosphorous metabolism in rats.Nature 136, 754, 1935.

GEORGE DE HEVESY1885-1966


Single probe Scanner Gamma camera

Bone Scan


• Activity Meter• Sample Counters• Survey Meters• Single- and Multi-probe Systems• Gamma Camera • Single Photon Emission Computed Tomograph (SPECT)• Positron Emission Tomograph (PET)• Positron Emission Tomograph- Computed Tomograph (PET-CT)

Instrumentation in Nuclear Medicine


Thyroid Uptake Measurement


1908 Visual scintillation (ZnS) Crookes1927 Geiger-counter Geiger1944 Scintillation detector (ZnS+PM) Curran1948 Sodium iodide crystal Hofstadter1950 Scanner Cassen1957 Gamma camera Anger1963 Tomography Kuhl1961 PET Robertson2000 PET-CT Townsend

History- Instruments


B. Cassen H.O. Anger

Pioneers


Gamma Camera?


Gamma Camera


Nuclear imaging detects functional (vs. anatomical) properties of the human tissue.

The imaging is done by tracing the distribution of radiopharmaceuticals within the body with a gamma camera

Nuclear Medicine Images


Bone uptake of 99mTc MDP reflects bone metabolism and blood flow, and allows functional analysis of bone turnover

The ability to image bone metabolism alterations enables detection of lesions such as:

Bone metasasis Benign or malignant bone tumorsBone trauma

A three-phase acquisition procedure is required in order to detect osteomelitis

Bone scans also facilitate follow-up of other bone disorders, such as Paget’s disease

Intravenous injection of 400-600 MBq 99mTc MDP. Imaging 3h after injection

Bone Scan


normal pathologic

Bone Scan


A proportionately spread embolization of the pulmonary capillary bed yields an image reflecting the lung blood perfusion (Tc99m MAA). This image enhances the diagnosis of pulmonary emboli.

Intravenous injection of 100 MBq Tc99m MAA. Immediate scanning.

Ventilation studies (Tc99m -aerosols) reflect the regional and segmental ventilation. Study interpretation is performed in conjunction with perfusion findings, supporting the differential diagnosis of pulmonary emboli.

Inhalation of 100 MBq Tc99m -aerosols.

Immediate scanning.

Lung Scan


Lung Scan


Thyroid scintigraphy (I123, I131 or Tc99m pertechnetate) offers structural and functional information by displaying the thyroid image and calculating uptake, organ volume etc. Pinhole SPECT studies offer superior contrast resolution image over the planar image, enhancing thyroid nodules detection and evaluation.

Intravenous injection of 100 MBq Tc99m pertechnetate or 30 MBq I-123 po.

Thyroid


Thyroid Scan


Cerebral Blood Flow

99mTc HMPAO or similar compound - retained in the brain in proportion to regional cerebral blood flow.

Localizes predominately in thegray matter and does not show

redistribution.

Enhances detection of :

Brain dementia such as Alzheimers disease, seizure localization Foci, Cerebral vascular problems such as cerebral ischemia, trauma and brain death

Intravenous injection of 800 MBq 99mTc HMPAO. Tomography 30 min later


normalnormal Alzheimers diseaseAlzheimers disease

Cerebral Blood Flow


• Determination of kidney clearance of Cr51-EDTAor Tc-99m DTPA.

• Dynamic renal scintigraphy reflects renal blood perfusion, uptake and excretion. The acquisition yields a series of images. By calculating count rate in a defined ROI, a renogram is created, providing quantitative data. Different radiopharmaceuticals, such as Tc99m-MAG3, Tc99m-DTPA and I123-Hippuran, are used for renal clearance and function assessment.

• Renal scan for parenchymal anatomy and function evaluation uses Tc99m-DMSA

Kidney Function


It is ideal to mark the background region in such a manner as to exclude the arteries and calycial region.

Kidney Function (Tc99m-DTPA)


Kidney Function (Tc99m-DMSA)


• Intravenous high activity (400-800 MBq) Tc-99m bolus tracer injection, followed by a short acquisition (4-20 frames per second during 1 minute) demonstrates Myocardial function eliminating background activity bias.

• First pass procedures facilitates:

• Wall motion imaging• LV and RV ejection fraction calculations• Detection of left to right intracardial shunts• Cardiac output calculations• Ventricle volume calculations• Transit times calculations

First Pass Study


Shunt Quantification


ECG-Gated Blood-pool Scanning

• Red blood cell labeling (Tc99m), followed by gated acquisition and measurement of the corresponding dynamic blood volume count rate changes, enables LV and RV blood volume quantification. The analysis of ventricular wall motion, systolic/diastolic functions, and Ejection Fraction, has application for CAD evaluation, risk stratification, and monitoring of cardiotoxicity in chemotherapy treatments.

• Intravenous injection of 600-800 MBq Tc99m , scanning 10-15 min later.


ECG-Gated Blood-pool Scanning


Myocardial Perfusion

• 201Tl accumulation in the myocard depends on blood flow and cellular metabolism, hence, reflects regional perfusion and viability of the cardiac muscle.

• The evaluation of a patient suspected or known for C.A.D. is based on image interpretation or quantitative analysis from reconstructed tomographic slices, which also yields regional perfusion information.

• The examination is performed under maximum stress condition and after rest.

• Injected activity 70-100 MBq 201Tl. Tomographic study.


Stress Rest



coronal

transversal

sagittal

Tomographic Slices




• The physical properties offered by 99mTc MIBI or Tetrofosmin facilitate evaluation of myocardial perfusion and function by enabling performance of gated SPECT perfusion studies initiated with first pass acquisition. The assessment of a patient with known or suspected C.A.D. is based on quantitative analysis and coronary artery regional perfusion evaluation, drawn from a set of reconstructed tomographic slices.

• Injected activity 800-1000 MBq. Gated tomographic acquisition



ECG-Gated Myocardial Perfusion


Gated SPECT


PETPositron Emission Tomography


AnnhilationAnnhilation

++

++

--

511 keV511 keV

511 keV511 keV

positron


Radionuclide Half-life Particle energy (mean)

C-11 20.4 min 0.39 MeVN-13 10 min 0.50 MeVO-15 2.2 min 0.72 MeVF-18 110 min 0.25 MeVCu-62 9.2 min 1.3 MeVGa-68 68.3 min 0.83 MeVRb-82 1.25 min 1.5 MeV

Radionuclides


PioneersPioneers

Michel Ter-Pogossian prepares a radiopharmaceutical for anexamination of Henry Wagner Jr with one of the first PET-scanners (1975).


PET-Scanner


Stanley Livingstone and Ernest Lawrence with their 8 MeV cyclotron (1935)

Cyclotron


Cyclotron in HospitalsCyclotron in Hospitals


F18-FDGF18-FDG


FDG in CardiologyFDG in Cardiology


FDG in OncologyFDG in Oncology


Alzheimers disease Normal

FDG in Neurology

Nuclear Medicine

Rb-82 generators


• Produce rubidium Rb 82 chloride injection for intravenous administration. The eluate is sterile and non-pyrogenic

• Rb-82 is used for non-invasive investigation of myocardial perfusion with PET imaging

Rb-82


•New radiopharmaceuticals based on positron emitters.•Radiopharmaceuticals with high specificity.•More advanced application programs which improve both sensitivity and specificity of the examination.

The FutureDiagnostic Methods


Multimodality Imaging

PET

CT

Nuclear Medicine

Generator-based PET Radiopharmaceuticals

• Ge-68/Ga-68 and Sr-82/Rb-82 generators have potential for PET radiopharmaceuticals in molecular imaging

• Potential use of Ga-68 labeled peptides in PET imaging


Nuclear Medicine

Therapeutic Radiopharmaceuticals

• Molecular targeted radiotherapies

• Lu-177 and Y-90 labeled compounds for peptide receptor radionuclide therapy (PRRT)



• Improved performance of the gamma camera

• Improved detection of positron emitters• More sophisticated methods for

reconstruction and correction of tomographic examinations

• Advanced electronic reporting systems.

The FutureInstrumentation


No! Nuclear medicine is an efficient diagnostic and therapeutic tool and is justified from a medical point of view.

NUCLEAR MEDICINE - UNCLEAR MEDICINE?

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RADIATION PROTECTION IN NUCLEAR MEDICINE

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