GENERAL CONCEPTPRESENTED BY

Dr. LANA HAIDER AHMED

NUCLEAR MEDICINE

OBJECTIVE

Part 2: Radiation Physics 2

To become familiar with the concepts of Nuclear Medicine techniques, major areas are presented, namely:

1- Nuclear Medicine Methods.

2- Radiopharmaceuticals.

3- Instrumentation.

4- Radiation Protection & Safety.

NUCLEARMEDICINE

For what?

How it works?

History

What is that?

What is Nuclear Medicine? Nuclear medicine is a branch of medicine and medical

imaging that uses radioactive substances in diagnosis and therapy.

These substances consist of 1-radionuclides, 2-pharmaceuticals that have been labelled

(radiopharmaceuticals

imaging spec ia l ty tha t focuses on the use of “radiopharmaceuticals” for diagnosis, therapy, and medical research.

History of NM. The history of nuclear medicine over the past 50 years reflects the strong

link between government investments in science and technology and advances in health care worldwide.

New nuclear medicine procedures have been developed that can diagnose diseases non-invasively, providing information that cannot be acquired with other imaging technologies; and deliver targeted treatments.

Nearly 20 million nuclear medicine procedures using radiopharmaceuticals and imaging instruments are carried out annually in the United States alone.  

Overall usage of nuclear medicine procedures is expanding rapidly, especially as new imaging technologies, such as positron emission tomography/computed tomography (PET/CT) and s ingle photon emiss ion computed tomography/computed tomography (SPECT/CT), continue to improve the accuracy of detection, localization, and characterization of disease.

How does nuclear medicine differ from other types of radiology?

Nuclear medicine differs from other modalities that you may know about, like CT or MRI, in that those studies are anatomically based. They look at anatomy structure.

Nuclear medicine looks at physiology of the body and of all the organ systems. We can follow the physiological processes a s t h e y o c c u r i n a l i v i n g h u m a n u s i n g t h e s e radiopharmaceuticals and through use of appropriate imaging systems.

NM DETERMINE THE CAUSE OF A MEDICAL

PROBLEM BASED ON ORGAN OR TISSUE FUNCTION.

PHYSIOLOGY THE EMPHASIS OF NUCLEAR MEDICINE

S T U D I E S I S M O R E O N F U N C T I O N A N D CHEMISTRY THAN ANATOMICAL STRUCTURE

CURRENT DIAGNOSTIC METHODS

10

• ImagingBone, Brain, Lungs , Thyroid, Kidneys, Liver/spleen, Cardiovascular, Stomach/GI-tract, Tumors, Abscesses

•Non-imaging (probes)Thyroid uptake, Renography, Cardiac output.

Laboratory testsGFR, Ferrokinetics, Red cell volume/survival, Absorptionstudies (B12, iron, fat), Blood volume, Exchange-able electrolytes, body water, bone metabolism…..

•Radioimmunoassays (RIA)•Peptide Hormones, Steroid Hormones, Drugs,Vitamines,Brostaglandis------etc.

Imaging Methods Examination can be described on the basis of

imaging method used: Static Whole body Dynamic Single photon emission computed tomography, SPECT Positron emission tomography, PET

Common Nuclear Medicine Investegations NEUROLOGIC

Diagnose stroke Diagnose Alzheimer's

demonstrate changes Disease in AIDS

Dementia

ONCOLOGIC

Tumor localization - tumor staging

Identification of bone pain due metastatic cancer

Common Nuclear Medicine Studies RENAL Diagnose renovascularobstruction,

hypertension

Detect renal transplant Rejection - renal

function

CARDIAC Select patients for artery bypass or

angioplasty localize toxicity due to

acute myocardial Chemotherapy infarction Identify cardiac shunts

Common Nuclear Medicine Studies PULMONARY

Diagnose & quantify pulmonary function

Emboli perfusion Detect pulmonary complications of

AIDS

ORTHOPEDIC

Identify bone trauma

Diagnose osteomyelitis

Evaluate arthriticchanges

Common Nuclear Medicine Studies OTHER COMMON APPLICATIONS Diagnose and treat thyroid cancer Hyperthyroidism or metastatic spread Detect acute GI & cholecystitis bleeding Detect testicular torsion & infections

Radio nucleotide Imaging Image is generated

using radioactive decay from an organ

Usually a function of time.

Provide functional information

Radionucleotide Imaging (Cont..)

Scintillation Camera Shows two dimensional data Studies physiologic function

Radionucleotide Imaging(Cont..) Single detectors are used

for thyroid studies.

TomographyThe fourth class of imaging is the

Tomographic reconstruction of body slices.Single-photon emission computer tomography - SPECT scanPosition Emission Tomography – PET scan

SPECT SCANNER

PET Scanner

PET image showing malignant breast mass that was not revealed by conventional imaging techniques such as CT, MRI, and mammogram

PET image of same patient with enlarged left axillary lymph nodes (indicated by arrows), which through biopsy were found to be metastatic. The whole body scan reveals a mass in the left breast (indicated by arrow), that was malignant and subsequently removed

65 year old male with brain tumors imaged here with a PET scan.

PET/CT & SPECT/CT Now available is a blending of imaging function and

form. By merging the functional imaging of PET and SPECT with the anatomical landmarks of CT

More powerful diagnostic information is obtainable.

Non-Imaging StudiesGFRIodine UptakeBlood VolumeMalabsorption (Shilling test)Radioammunoassay (R I A)

Non-Imaging StudiesThyroid probe (Non-imaging device)

Radionuclides Artificial radionuclides are generally produced in a

cyclotron or some other particle accelerator, in which we bombard a stable nucleus with specific particles (neutrons, protons, electrons or some combination of these).  By doing so, we make the nucleus of our starting material unstable, and this nucleus will then try to become stable by emitting radioactivity.

RADIOPHARMACEUTICALSRADIONUCLIDE

IS TAGGED TO APHARMACEUTICA

L

PHARMACEUTICAL

CHOOSEN BASED ON THE PARTICIPATION IN THE PHYSIOLOGIC FUNCTION OF A GIVEN ORGAN

RADIOPHARMACEUTICALS

ARE ADMINISTERED TO PATIENTS.

THEY NEED TO BE STERILE

How does this stuff work?1- Getting the gamma ray to the right spot. 2- Radiopharmaceutical injection. 3- Imaging the gamma rays. 4- Gamma cameras. 5- Producing useful information from images. 6-Collimation,filtering,electronic discriminators,

electronic amplifiers. 7- Computerized data process.. 8- Reporting

“RADIOPHARMACY UNIT”

The Main Players

Isotope Decay T-1/2 Energy Production Tc99m IT 6 hrs. 140 KeV Gener. I-123 EC 13 hrs. 159 KeV Cycl. I-131 B- 8 days 364 KeV Reactor Tl-201 EC 73 hrs. 69-83 KeV Cycl. In-111 EC 68 hrs. 171, 245 Kev Cyc. Xe-133 B- 5.2 days 81 KeV Reactor F-18 B+ 110 min. 511 KeV Cycl.

Patient Prep. & Safety For NM procedures prep is minimal, most tests

requiring no special prep. A few procedures the patient will need to be NPO Pt. Usually remain in their own clothing, removing

all metal objects. Metal can mimic pathologic conditions.

Patient Prep & Safety Pt. first receive the radiopharmaceutical injection

and then will return for imaging in a interval time. (minutes to hours

Waiting time between dose administration and imaging varies with each study

Some radiopharmaceuticals require the Pt. to remain in isolation after injection, or require special disposal of urine products

What are the benefits and risks of nuclear medicine? * Well, the benefits of nuclear medicine is quite a lot, and it

has contributed to the well being of humans for long time through helping with diagnosis and especially more recently helping with therapy in many of the conditions that humans suffer. * For example, thyroid cancer and more recently lymphoma.

* There is a radiation risk but that's also very small, and it's approximately the same level you receive from natural sources.

Therefore the benefit to risk ratio for nuclear medicine is tremendous.

REFRENCES 1-Nuclear Medicine Procedures Manual . 2- Essential of Nuclear Medicine 5th edition. 3-Nuclear Medicine(LANDES BIOSCIENCE). HARD COPIES: 4- Practical Nuclear Medicine(OXFORD MEDICAL

PUBLICATION) Peter F Sharp Second Edition. 5-Fundementals of Nuclear Pharmacy(Springer) Gopal

B. Saha

Questions