Nuclear Flashcards
basic steps of nuclear
a suitable radiopharmaceutical is introduced to the patient
the radiopharmaceutical is allowed to concentrate in a a specific organ
rhe organ is scanned using an appropriate scanner
functions of NM
- Physiological measurement
- Lung, heart, kidney, bone
- Diagnosis of primary tumours
- Diagnosis of secondary tumours (metastases)
- Radionuclide therapy
2D- planar imaging technique
3D- SPECT and PET
overview of spect
Single photon emission computed tomography
Uses similar / same radiopharmaceuticals as 2D imaging
e.g. technetium based
Mode of acquisition changes
i.e. how the data is acquired and processed
Cross-sectional imaging
radioisotope
any isotope which is radioactive
isotope
any nucleus which contains the same atomic number as the given nucleus but different mass number
unstable nucleus
the strong nuclear forces do not generate enough NBE to hold the nucleus together permanently
unstable nucleus tend to attain stability by emitting extra energy in the form of radiation and convert into stable nucleus to lower energy - process called radioactive decay
what is alpha decay
spontaneous emission of an alpha particle
the nucleus should have an A>150 and must have too few neutrons for the number of protons
they have a short-range in tissues so have little pratical applications
what is beta decay
nucleus should contain too many neurons
conversion of neutrons to protons and vice versa
a particle having a mass equal to that of an electron is ejected from nucleus
the particle can have either a positive (positron) or negative charge (negatron)
what is gamma decay
gamma ray emission
What is the difference between Gamma ray emission and alpha or beta decay
Gamma ray emission (not particulate like alpha or beta decay
The physical half-life of Technetium-99 metastable is 6 h. How much activity is needed at 9 am if 80 MBq is needed at 9 am next day?
A.2000 MBq
B.1280 MBq
C.320 MBq
D.160MBq
B.1280 MBq
Which of the following radiopharmaceuticals is useful in positron emission tomography (PET) scan for detecting malignant tumours?
A.Technetium 99m DTPA
B.18-Fluorodeoxyglucose
C.Technetium 99m Pertechnetate
D.Technetium 99m HIDA
B.18-Fluorodeoxyglucose
What is technetium
•Technetium is an radioisotope (gamma ray emitter) and DTPA is excreted by kidneys and hence allows the measurement of renal function (DTPA scan or renogram)
Describe the detector from a gamma camera
- Scintillation crystal
- Usually sodium iodide crystal doped with thallium
- Converts gamma radiation into visible light
- Inefficient process
About 10% of incident gamma radiation converted to light
Define Effective half-life
is the time taken for the activity of a certain radionuclide in a certain organ to be reduced to half of its original activity.
•1/t1/2(eff)=1/t1/2(phys)+ 1/t1/2(bio)
Define Biological half-life
•is the time taken for the concentration of a certain chemical in an organ to be reduced to half its original concentration.
ideal isotopes should have
a short half life
emit gamma-rays of relatively low energy
emit no particles
be added to the pharmaceutical without altering its chemical energy
be readily excreted
be easily generated
what gamma rays are only deteced
only ones perpendicular to the detector as best quality
high sensitvity
photomultipliers further apart
get as many rays as possibe
high resolution
photomultipliers closer together
only get good quality rays
what is the gamma ray detector made up of
scinillation crystals
usually sodium iodide crystal with thallium
converts gamma radiation into visible light
inefficient process - about 10% of incident gamma radiaition converted to light
the photomultiplier tube
makes the detector more efficient
mulitplier small light beam into lots of electrons
light beam hits cathode, generating electron, electron hits dynode which produces more electrons
electrons get to anode
overview of PET
PET (Positron emission tomography)
Different pharmaceutical to planar and SPECT imaging
FDG (Flurodeoxygluocose) (18
Radiopharmaceuticals decay by the emission of positrons
Annihilation – positron travels a few mm then interacts with an electron
Two gamma photons are emitted (511 keV)
1800 opposed to each other
The camera detects gamma rays to produce the image
overview of SPECT
Single photon emission computed tomography
Uses similar / same radiopharmaceuticals as 2D imaging
e.g. technetium based
Mode of acquisition changes
i.e. how the data is acquired and processed
Cross-sectional imaging
role of nucelar
physioloical measurements
lung, heart, kindeys and bones
diagnosis of primary tumors
diagnosis of secondary tumors
use on bones
cancer staging
inject radionucleotide which is taken up by osteoclasts
send them away for 2-3 hours, ask them to drink lots
scan
use in lungs
perfusion and ventilation imaging
pulmonary embolism
use in GI
Gi bleeds gastric emptying gastric reflux gall bladder bile
use in heart
disease
- MI
- ischemia
- at exercsie and rest
- planes and SPECT images
use in neurology
cerebral perfusion imaging
dopmaine receptor imaging
tumors
lympathetic system and lymph nodes
