9. Nuclear Medicine Flashcards
what does nuclear med utilize to investigate disorders
nuclear properties
what 3 disorders can nuclear med be utilized to investigate
metabolism and function
physiology and pathophysiology
anatomy
what is the source and what picks up the radiation
patient becomes source and camera picks up rad
does the machine emit rad
no
what are radiopharmaceuticals
compounds chemically labeled with specific radioactive material - radioisotope
what do radiopharm do in organs
concentrate in organ/organ system
what is a benefit of getting physiological info in nuc med
Physiological metabolic info so can image disease at earlier stage as the physiological/functional changes begins before anatomic changes
what does nuclear med demonstrate
physiologic or anatomic changes at molecular level
what images do nuclear med show
anatomic and functional images
what are nuclides
have exact nuclear composition
what must nuclides be in terms of existence
long existence
what does a stable atom mean in terms of forces
forces between particles and nucleus are balanced/equal
what does an unstable atom mean in terms of forces
If unstable, forces are unbalanced and has excess energy it gets rid of by emitting particles or/and energy and we use to image in nuc med
what do unstable nuclei emit
particles/photons
what is the process of unstable nuclei emitting particles/photons called
radioactive disintegration or radioactive decay
what is the most stable arrangement
ground state
what is the excited nucleon state
nucleons that are so unstable they have transient existence before transforming into another state
how are excited or metastable states denoted as
with a superscript m
what do isotopes have in terms of same number
same atomic number and same number of protons
what do isotones have in terms of same number
same number of neutrons
what do isobars have in terms of same number
same mass number
what do isomeres have in terms of same number
metastable state
what is the neutron number worked out from
mass number - atomic number
what are radionuclides
an atom with unstable nucleus characterised with excess energy
what is radioactivity determined by
determined by unstable nucleus - number of protons and neutrons
what is radioactive decay
when energy is imparted in an attempt to reach stability resulting in emission of gamma rays and/or subatomic particles such as alphas or beta through various decay processes
what happens to atoms after they release radiation
radioactive atom transforms into different nuclide via radioactive decay and this continues until nucleus forces are balanced
atoms go from metastable state to ground state by doing what and what can we see
atom goes from metastable state to ground state by emitting energy and we can see what energy is coming off
what is radiation
energy or particles that are released during radioactive decay
what does the radioactivity of a material refer to
rate at which it emits radiation
what is the activity of a specific sample of radioactive material determined by
by measuring number of disintegrations per unit time
disintegrations occur when what happens
when nucleus emits a particle or energy
radioactivity is measured in what unit
becquerels
one becquerel is what in terms of disintegration rates
1 disintegration per sec
what is rate of radioactive decay expressed in terms of
radioactive half life
what is the half life in nuc med
time for radioactivity to divide by half the original activity
does nuc med have an effect on physiological process and why
no as only nano and picomolar amounts are given - its only for direction and uptake only
what is the physical half life for nuc med
definite half life of radionuclide
what is the biological half life for nuc med
defined as time needed for half of the radiopharm to disappear from biological system
what is the effective half life for nuc med
defined as time required for an initial administered dose to be reduced by half as a result of both physical and biological elimination of a radionuclide
can we change the physical half life
no as its determined by the element itself
can we change the biological half life
we can change
eg if its excreted by kidneys can give patient more water to drink so excretes It faster from system so shorter bio half life so can also reduce the dose that the patient is getting - bio half life is also affected by metabolism in body
what is the relative effective half life in relation to physical and bio half life
effective will always be shorter than phy and bio half life
what is the equation for Te or effective half life
Te = (Tp x Tb)/(Tp +Tb)
the amount of radioactivity in a source is measured by what
the rate at which atoms undergo radioactive disintegration
what is the traditional unit of radioactivity
curie
what is a radiopharmaceutical
a sterile, pyrogen free radionuclide or radioactively labelled compound administered to a patient for diagnostic or therapeutic purposes
do radiopharmaceuticals have pharmacological effect and why
It has no pharmacological effect due to the small amount of material administered
__ + ____ = radiopharmaceutical
radionuclide + pharmaceutical
radiopharmaceutical’s radionuclide component has what 4 characteristics
radioactive substance
emits gamma, beta or alpha rays by decaying to a stable state
gamma camera detects these gamma rays for imaging
has specific energy physical and biological half life
radiopharmaceutical’s pharmaceutical component has what 4 characteristics
cold kit
specifically designed to target an organ or biologic process in the body
without the radionuclide attached we cannot image where the pharmaceutical went
has a biological half life
what is the relationship between radionuclides and pharmaceuticals in terms of which is needed to be present for imaging to be possible
radionuc can be used and imaged without pharm
pharm cannot be imaged without radionuc
what is a radiopharm kit
mini portable pharmacy which provides chem ingredients and accessories for hospital prep and admin
what does the cold kit consist of
freeze dried reagents in an atmosphere of nitrogen for reconstitution with a radionuc
are cold kits radioactive
no
kits have analogues of what
analogues of what body uses for specific functions
what are the 3 constituents of radiopharm kits
active ingredient
reducing agent
additives
what is the active ingredient of radiopharm kit
compound to be labelled with the radionuclide
if you dont reduce the radiopharm kit what happens
there wont be a labelling reaction
what is the most common for nuc med routes of administration
IV
why is intravenous administration common for nuc med
Intravenous is most common as it requires smaller volumes (pharmaceutical smaller doses and radioactive part use range of small to large)
why is it important for smaller volumes to be used in administration
Want these things to be smallest volumes possible as we are handling radioactivity and getting irradiated ourselves so if you administer smaller volume, less time to administer to patient as less dose to us as MRTs
what is a benefit of IV administration for nuc med in terms of absorbtion
IV also doesn’t get absorbed by GI tract and go straight to target organs so extracted from blood a lot faster than orally and limits radiation dose to non target organs
what is a benefit of IV administration for nuc med in terms of contamination
IV a lot faster and controlled, orally may vomit and radiation contamination with everything
what is instillation administration used to investigate in nuc med
ducts and tracts and glands
what is intracavitary administration used to investigate in nuc med
administer directly into the tumor or disease were trying to target
what is topical administration used to investigate in nuc med
skin lesions
injection administration in nuc med needs what admin method
bolus - small volume
what IV administration factors affect the scan
injection factors
why is slow administration needed for some imaging such as MRPG
its a catecholamine/adrenaline analogue as if injected too fast it will cause fight or flight response
what should we consider when administering injections into lines
Avoid preexist lines as radipharmac will adhere to sides of line
gastric emptying rate can be determined by what process
administer a radiolabelled meal to the patient followed by sequential imaging
what is the application of intrathecal administration
CNS
what is the application of intra-articular administration
therapy for painful joints
biochem nature of carrier molecule and radiotracer has effects on what 4 things
organ uptake
retention
tranportation
biodistribution
localization mechanism is specific to what
targeted organs
are radiopharm limited to a single mechanism and why
no require a combo of more than one mechanism
Localisation not limited to single mechanism, depends on processes in body already like particle trapping, antigen antibody reactions, If body removed damaged cells eg deliberately damage artificial RBC and put in body after tagging to see spleen activity
the physicochem properties of the radiopharm influence what factors of ADME in terms of smaller sizes
smaller size impacts the elimiation in VQ studies/colloid
the physicochem properties of the radiopharm influence what factors of ADME in terms of lipophillicity
affects the solubility and therefore the pathway the radiopharm can follow
the physicochem properties of the radiopharm influence what factors of ADME in terms of ionization
charge of molecule plays a role in thyroid and renal imaging
what are the 4 main ways that radiopharm are excreted
exhalation, renal, GIT (incl hepatoniliary) and GUS
the distribution fo the radiopahrm depends on what 4 factors
perfusion to the organ or tissues
mechanism of uptake
underlying physiological principles
excretion
the characteristics of the radiopharm determine the ADME based on what 2 factors
human physiology and function
what is the ideal radiopharm characteristics in terms of type of emission, explain
Type of emission want is decay to gamma rays emitted for imaging but want radionuclides that emit B particles for treatment
what is the ideal radiopharm characteristics in terms of photon energy, explain
Energy value between 100-250keV, if energy too high gamma pass straight through collimator and cause scatter but if too low acquisition time is too long, must be emitting correct range of energy
what is the ideal radiopharm characteristics in terms of poly/monochromatic photon energy, explain
Want monochromatic so majority of photons are same energy and should be lot of these photons per unit area per unit
what is the ideal radiopharm characteristics in terms of proton abundance, explain
High proton abundance = high proton flux so can image patient in reasonable timeframe and decent image quality
what is the ideal radiopharm characteristics in terms of radioavailibility, explain
Radioavailibility = obtain easily in house through radionuclide generator
what is the ideal radiopharm characteristics in terms of cost, explain
Inexpensive is relative as one unit dose of MPG is 200-400$
what is the ideal radiopharm characteristics in terms of half life, explain
Controlled half-life, Tc has half-life of around 6hrs so it means theres enough time to image patient but not that long that they get too much radiation dose
what is the ideal radiopharm characteristics in terms of effective half life, explain
Ideally the effective half life should be 1 and a 1/2 times the duration of the test (eg if bone scan is 3hrs, want effective half life to be around 6hrs)
what is the ideal radiopharm characteristics in terms of high target:non target ratio, explain
Want target organ to take up most of radiopharmeutical and to miss the non target organs
what is the ideal radiopharm characteristics in terms of safety, explain
Safety, radiopharm have to be non pyrogenic and not deliver too much rad dose to patient
what is the ideal radiopharm characteristics in terms of preparation, explain
Preparation of radiopharm is done ourselves and should not take too long to prepare as still need to administer to patient without running out of radioactivity
what is the ideal radiopharm characteristics in terms of what gamma and beta radiation can be used for
Radioisotope were using should be pure gamma emitter for imaging and Betas for therapy and should be nontoxic to patients
what is the mineral form of bone
hydroxyapatite crystal
what does bone scintigraphy utilize
physiology of bone formation and remodelling
radiopharm is chemisorpted into what
chemisorption of the radiopharm to the hydroxyapatite crystalline structure
what happens when bone is damaged
Bone gets laid down with osteoclasts/blasts remodelling the bone
Increased blood flow to that area
increased blood flow in response to damaged bone is significant for what in terms of radiopharm
Increased perfusion/blood flow to that area so administer radiopharm in those areas, will have more radiopharm deposited at the injured sites so wont look the same
Bone remodelling and increased perfusion is what delivers radiopharm there
how to tell where areas of abnormality are on bone scans
hot spots
thyroid require what to produce thyroid hormones
iodine
iodine is administered how in thyroid investigation
Administer iodine orally not IV and body interprets this as normal iodine to make hormones so iodine is trapped in thyroid and can see if thyroid is under or over active
what is thyroid scintigraphy uptake based on
physiology of thyroid hormone production
what are 2 examples of thyroid indications
diagnose hypo/hyperthyroidism
image nodules
can 131I-sodium iodide be used for imaging and treatment
yes as it emits gamma and beta
can 99mTc pertechanetate be used for treatment
no only emits gamma and not beta so good for imaging, not treatment
what is used to do brain imaging
uses BBB as advantage and lipophilic agent to image the perfusion of the brain
how is the brain imaged in nuc med
Administer lipophilic pharamaceutical with rapid first pass uptake
once in brain, its metabolised into its hydrophilic form and cannot diffuse out of BBB and can use to image
what are adverse reactions defined as
unanticipated response to the non radioactive component of a radiopharm
are nuclear med adverse reactions caused by radiation
no, over use of radioactivity not adverse reaction but is a reportable events
reactions are caused by pharmaceutical parts
