Radiopharmacy Flashcards
what is nuclear medicine?
scans that give poor anatomical detail but do show functionality of the organs
what are radiopharmaceuticals made out of?
‘useful molecule’ that allows us to target desired organ
+
radioactive isotope that acts as tag for detection on imaging
Does nuclear medicine show anatomy or function?
function
Do XRAYS and CT show good anatomical detail or good indication of function?
anatomical detail/ anatomy
briefly describe how a gamma camera works? and outcome?
px given radioopharmaceutical + gamma photons detected by detector camera… gives pic of organ
why/how are only gamma photons detected by detector?
as dont interact with tissue= dont directly damage px, but are detected
whats a collimator? what does it detect/not detect?
sheet of lead with holes to allow certain gamma emissions to come out + be detected by detector of gamma camera,
so those at angle arent detected and plotted
what is the measurements used for radiation energy in tissue?
sievert (Sv)
how much is mSv?
1/1000
how much is a microSv?
1/1 000 000
how much bits of energy absorbed is NOT JUST influenced by how radioactive it is, but also by what else?
(what 2 factors affect Sv?)
how its been shielded (lead thickness)
how been stored
effect of shielding/ not shielded vial of radiation, on your abdorbed radiation dose after you sit next to it.
provided same amount of radioactivity in vial?
no shield: your absorbed radiation dose (sc/msv) increase
shield: amount of energy px absorbs lower (msv exposed to)
2 points to philosophy of radiation protection?
- all exposures shall be justified (benefit > risk)
- all exposures shall be kept ALARP
why is ALARP important?
as it means that the radiation given to a px is AS LOW AS REASONABLY POSSIBLE
4 sources of radiation that humans are exposed to in small amounts?
cosmic radiation, radon gas, buildings and food
average natural radiations for UK per year?
2.5mSv. but will inc if have scan etc
why does the soil in cornwall give off the most radon? thus inc mSv?
has the most granite which gives off radon gas
highest radiation workers?
airline staff
several mSv per year
what are effects of long exposure of radiation?
effects the bone marrow
skin reddening / burning
pelvis radiotherapy = diarrhoea
neck radiotherapy = vocal chord damage
what is the main concern of radiation?
carcinogenesis
(normal cells-> cancer cells)
assume risk whatever the dose
what is the radiation risk for 2mSv exposure of harm?
1 in 15 000
what is the inverse square rule?
strength of the X-ray beam is inversely proportional to the square of distance from the source (X)
i.e.
if you decrease the distance from radioactive source by 1 the area of exposure increases by 4
how to reduce and limit radiation exposure?
time
distance
shielding
… sops, staff training, monitoring and feedback
L2:
diagnostic use of radiopharmaceuticals? to get info on …
struc, function or degree of involvement with a disease process of organ/ body tissue
why might patients with breast or prostate cancer have radiopharmaceutical bone scans?
see if it is spread and there are bone lesions
why might the bladder come up as dark under gamma cameras?
radioactive substance in excess will go to bladder as it is excreted in the urine
how can low radiation dose be maintained for patients? 3 idealistic PK of radiopharmaceuticals
- use radionuclide with short physical half life
- short biological half life
-nature of radioactive decay
what’s the difference between physical and biological Half life?
physical- time to reduce radioactivity level to 1/2 original value due to radioactive decay.
biological- time for biological system to eliminate 1/2 of substance (such as a radioactive material) that has entered it.
how long should a radionuclide usually hang around for in the body?
2-3 hrs
which unit of radiation relates the rate of disintegration but does not tell you anything about the radiation dose to px/ workers?
becquerel
how many becquerels is equivalent to 1 distintegration per second?
1 d.p.s
why do nuclei disintegrate?
nuclei unstable, want become stable by disintegrating + getting rid of energy as gamma photons/a/b parts.
each time it disintegrates = 1dps = 1 becquerel
what do radioactive substances release in order to remain stable? 3 types of radioactive decay
gamma photons or alpha and beta particles
are beta and alpha particles useful for diagnostic imaging, yes or no?
no
if you have a vial of radioactive substance, what happens to the becquerels and sieverts if you place it in an appropriately lined lead container?
b stay the same and s decrease
alpha particles are essentially He nuclei with a +2 charge. Why are they not suitable for diagnostic testing in the body? 3
large, collide with tissue (dont go straight through) and give up energy, considerable damage in small area
alpha particles can be shielded easily but cause lots of damage if ingested or touch skin , true or false?
true, so must wear gloves
beta particles have a negative or positive charge and are smaller than alpha particles so have less damage and interaction with tissue. Why can they therefore not be used for diagnosis?
still interact with tissue and cause some damage
what does range (of several cm) of b particles depend on?
energy Emax and Emean
B+ particles aka positrons - antimatter interact with what and when?
b- particle immediately after emission form nucleus
Annihilation reaction: matter -> pure energy with 2 gamma photons emitted.
b+ + b- –> what? in an annihilation reaction
2y (gamma photons)
B+ particles aka positrons - antimatter - valuable in diagnostic procedures, yes or no?
yes
are gamma rays electromagnetic (EM) radiation or particulate?
EM radiation
why are gamma rays more suitable to be used in tissue?
less interaction, cause less damage and have greater range .. in tissue
valuable for diagnostic
is the energy of emitted gamma rays constant or variable for a given nucleotide?
constant
what are the 9 ideal diagnostic properties?
- gamma ray emission only
- for imaging studies, 100-250 Kev
- physical half life of approx. 1.5x(test duration)
- simple cheap, rapid production
- versatile chemistry
- chemical quantity
- radiochemically pure sample
- chemically stable
- predictable biodistribution
for diagnostics,
want gamma ray remission only in X abundance, and to Y radiation dose to px
high
reduce
for diagnostics: imaging studies, want gamma energy of 100-250kev. 3 reasons why?
high detection efficiency,
no significant body attenuation
easy to shield
what can be done to reduce body attenuation in overweight patients to obtain good imaging?
inject more radioactivity into them
physical half life of diagnostic radionuclide should be approx how many times the duration of the test?
1.5
for dianostics, want simple cheap and rapid production, why?
to reduce handling time and exposure.
- lack of radionuclidic impurities
- high specific activity (conc.ed)
- rapid prodn reduces operator dose
? for diagnostics, why do you want radiochemically pure radiopharmaceutical? (biodistribution profile)
radiopharm. made is mostly bound to ligand. = most of uptake in organ you want + not impurity = gets taken up elsewhere, doesnt contribute to pics
for diagnostics, why do you want predictable biodistribution?
so from pics you can tell whats normal/not
Technetium 99m (Tc) is a manufactured element with an atomic number of 43 and has 20 different isotopes, which are all…
radioactive with t1/2 of few secs - millions of years
what is the half life of Tc 99m?
and y energy?
6 hrs
140keV
explain what is meant by meta stable?
e held further from nucleus and energy being used to hold, spontaneously it drops down closer to nuc and energy emitted by nuc as a gamma photon
what does Tc decay to?
Ru 99
see Tc-99m diagrams p37,38
whats emitted in 99Mo -> 99Tcm reaction/ what does 99Mo split into?
b- and y
2) whats emitted in 99Tcm -> 99Tc reaction?
y
3) whats emitted in 99Tc -> 99Ru reaction?
b-
why dont we give 99Mo to patient? and how will it be changed to be able to be given?
high energy-> very high radiation dose :(
would have to react and change to 99Tcm -> 99Tc -> 99Ru
why can Molybdenum and Technitium (Mo and Tc) be separated?
they have different chemical properties
what is the source of 99Mo?
from fission of U-235 in nuclear reactor
U-235 bombarded with thermal neutrons
nuc splits -> 2 daughter nuclei
large range of nuclides produces
Mo99 can be separated rel. easily
how does a technetium generator work?
how is Tc99m obtained?
shielded glass column packed with alumina, Mo99 in solid form (molybdate) is strongly adsorbed onto column
column sealed, sterilised, packed into generator
depatched to hospital radiopharm dept
Mo99 on column decays to Tc99m, which is separated
how is Tc-99m separated from Mo-99 in Tc generator?
saline passed through column, Tc is soluble so left with radioactive solution
What happens on an Mo column to get 99mTc
99Mo (some) spontaneously decays -> 99mTc. after saline passed through to separate.
how long does it take for a technetium generator to re-establish an equilibrium? (graph p 47)
22.89hrs (to get almost all Tc in there out)
check back once a day.
Tc drops, then inc again, both Tc and Mo dec over time
the chemical form of Mo is Molybdate, MoO4-, which decays to form what?
pertechnetate TcO4-
what process elutes pertechnetate TcO4-? (and eqn + name of reaction?)
passage of saline through alumina
Na+Cl- + TcO4- = Na+TcO4- + Cl-
ion exchange
sodium pertechnetate is used for how many days?
1
what is the term given to the ratio expressed as a % of the radionucelide concerned when compared to the total radioactivity of the source?
radionuclidic purity
Mo can get through the thickness of lead therefore any detection of radioactivity outside of the shield can be attributed to this, true or false?
true
if mo is low on first elution you can be confident that generator is suitable for use, true or false?
true
99Tc/99Mo generator radionuclidic purity identification not done routinely, but can identify what?
unknown isotopes (e.g. if have a spill)
can be useful with unlicensed material
3 methods to identify radionuclidic purity
- molybdenum breakthrough test
- gamma spectroscopy (measure energies emitted)
- measure decayed sample (determine half life)
give 4 things that choice of generator is based on?
ease of operation, efficiency + safety profile and cost
what grade of environment should elution happen in?
A
should the collection vial reach atmospheric pressure before or after removal? and why?
before to prevent aerosol production
generator: whats required to protect operator?
shielding
as Mo has high radiation
sodium pertechnetate can be administered directly in that form and is most commonly used for what indication?
thyroid imaging
why is pertechnetate taken up by thyroid?
similar in size and charge to chloride and iodide ions, thyroid mistakes it for iodide and uptake happens
sodium (99mTc) pertechnetate is more commonly manipulated to make Tc in diff chemical form, why?
diff chemistry = diff biodistribution
get info from different parts of body
TcO4 - chemically stable and Tc has a valency of +7. in order to make Tc react, what must be altered? and how/why can this be done?
valency state of Tc.
has partically filled N and O orbitals (?) as has 43 e- (atomic no).
Tc can exist in valency states of +7 to -1 and form range of coordination complexes
L3.
99m TC is eluted in most stable ox state (+7) and surrounded by big oxygens therefore ligand cant near it. How is it made more reactive in kits?
kits have tin ions which are more reactive, bind with oxygens and leave tc highly reactive, to attach to ligand / water to give Tc colloid
what is most frequently used in kits as a reducing agent?
stannous chloride (Sn++)
how are Tc radiopharmaceuticals prepared?
simple, usually single addition of TcO4- to kit - freeze dired vial
draw up eluent
dilute it
add to kit
wait 10/15 mins
complex forms
are most kits single or multi dose?
multi dose containers
all Tc prep manipulations are performed aseptically true or false?
true
NEVER inject air into any Tc radiopharm. vial.
what is one consequence of injecting even 0.1ml of air into a technetium vial?
can oxidise stannous ion used as a reducing agent
why do vials contain nitrogen atomosphere?
prevent oxidation of tin Sn++ stannous chloride
radiopharm kits contain all the required ingredients for prep of Tc radiopharms such as? lsbs
ligand
Sn++
buffers
stabilisers
radiopharm kits are amde into a…
single, sterile freeze dried rubber capped vial
how does addition of TcO4 into kit cause chem reaction?
it dissolves freeze dried powder to -> reaction
why is choice of ligand in Tc radiopharm prep important?
structure of Tc-ligand determines biodistribution (in px)
(Tc ligand choice) compounds with N,S,O,P atoms capable of what?
sharing/ donating e-
why are Tc complexes ligands prepared daily?
6 hr shelf life as radioactive starting material
give two benefits of limited handling and keeping prep simple as possible?
lower radiation exposure to staff
less chance of microbial contamination
(Example)
what does 99m-Tc bone radiopharmaceuticals do/ how do they detect tumours?
binds to hydroxyapatite.
greater the bone turnover, greater uptake.
can detect changes before change in bone density.
detect bony secondary metastasis
4 things that can go wrong in the reaction. (making a freeze dried kit?)
- make new chemical entity
- no reduction of TcO4- by stannous - free pertechnetate in kit
- reduced Tc doesnt react with ligand
- Tc ligand formed but unstable
quality control:
name of test that examines % of radionuclide present in the stated chemical form?
radiochemical purity determination RCP
% of TC ligand should be above X to pass?
and what does the other % include
95.
so free TcO4- and reduced Tc <5%. bit of impurities ok no big impact
what are the two separation methods that most assays rely on?
quality control of radiopharmaceuticals: to check > 95% Tc-ligand
HPLC (column chromat) and planar chromatography
3 forms of Tc present in radiopharm?
99m TcO4
99m Tc- ligand
99m Tc- colloid
an advantage of HPLC?
good separation
what are the 3 disadvantages of HPLC?
all activity may not be recovered, (eg lipophilic parts like Tc colloid will stick to column
expensive,
requires expertise
separation via planar chromatography is not always good but all activity may be measured. Give 2 things that can be used as a stationary phase?
ITLC SG
filter paper
for planar chromatography that uses paper as a stationary phase: one advantage?
good resolution
for planar chromatography that uses paper as a stationary phase: 2 disadvantages?
slower to develop,
poor mechanical strength: easy to collapse and tear (when wet)
planar chromatography may use instant thin layer chromatography ITLC as a stationary phase. what is the structure?
glass fibre web impregnated with modified silica
Although the silica gel and silicic acid are faster to develop (planar chromat: ITLC) what is one con?
poor resolution…
unlike with paper: more tightly packed as solvents move slowwer= better resolution
what mobile phases may be used to separate 99m TcO4 form mixture?
butanone or acetone
(as most pharmac. soluble in these)
mobile phase used to separate 99m Tc O4 and 99m Tc ligand from 99m Tc-colloid?
saline
.. then assay to check hm activity
mobile phases…
why is 99m Tc MAG3 an exception?
its more difficult to separate
how does the chromatography process work?
sample applied on bottom line in duplicate
flows up, takes anything soluble with it
cut strip in half and count activity on each half
remove when solvent reaches top line
assay and measure where radioactivity is
do smaller or larger samples give better resolution?
smaller.
spread out less :)
sample volume added for radiopharmaceuticals will depend on what?
radioactivity of sample - may need more if kit is dilute
what is the danger of allowing spots to dry? chromat
oxygen affects complex in sample giving wrong results
sample application can be done by what? (chromat)
microsyringe
disposable capillary micropipettes
through use of 1ml syringe and narrow bore needle
what is the method of processing a chromatogram that involves exposure to film to get a good image?
autoradiography
(once done and dried)
when processing chromatogram, what is it counted on?
gamma counter
processing chromatogram: how is signal passed to a chart recorder?
scan using chromatogram scanner
scintillation detector connected to ratemeter, then…
2 possible ways of chromatogram counting: cut and count
cut in half and count in dose calibrator
cut in smaller sections (eg 10) and count each section
give some problems that may occur with a QC test?
splashing when spotting
interaction with dyes
incorrect mobile ohase
insufficient mobile phase amount
uneven sample spotting
sample washed off by using too much mobile phase in camber
effect of problems occuring with a QC test on px:
free pertechnetate will be taken up by salivary glands, thyroid and stomach. where does reduced TC go?
liver and spleen
give 2 ways that incorrect testing in relation to too much free pertechnetate would affect a patient?
irradiation of unintended organs and subdiagnostic images
what is one danger to patients when they require a repeat scan?
doubling radiation dose to the patient
(from reduced Tc –> liver and spleen)
L: clinical aspects of radiopharmacy
what are radiopharmaceuticals?
Medicines that contain 1+ radioactive isotopes
what are radiopharmaceuticals used for?
on own/ tagged w tracer for investigations
Diagnostic and therapeutic purposes, most for diagnosing + cancer services
whats the most common diagnostic radionuclides?
99mTc (Technetium 99m most common),
list some therapeutic radionuclides.
131I (can have sodium iodide for treating thyroid cancer)
90Y
223Ra: symptomatic relief of pain associated with (prostate) cancer
177Lu for neuroendocrine tumours
how is Blood cell labelling used in diagnostics?
red/ white cells tagged with nuclei then used for diagnostic purposes
list the categories of Diagnostic applications of radiopharmaceuticals
- Respiratory system
- Musculoskeletal
- CVS
- CNS
- GI system
- Hepatic
- Renal
- Endocrine
- Infection +Inflammation
- Malignant disease
What is the use of radiopharmacy for the respiratory system?
diagnosis of pulmonary embolism, inflammation, neoplasm + COPD
what are the 2 scans done for resp system diagnostic use?
lung perfusion
lung ventilation
an IV injection of 99mTc MAA can be given so particles lodge in the terminal of aterio capillary bed and areas of reduced uptake could be caused by PE.
Is this diagnostic test for lung perfusion or lung ventilation?
lung perfusion
is Inhalation of a radioactive gas (81mKr or 99mTc Technegas) a requirment for lung perfusion or lung ventilation?
lung ventilation
radiopharmacy can be used to investigate lung perfusion and ventilation to diagnose PE. How can the two scans be used to indicate PE?
mismatch between scans
how would the PE resp lung scan differ to normal?
normal: even distributionm of radiopharma. uptake and can see outline of lungs
perfusion scan of PE: cant see outline.
mismatch. blockage blood + tracer cant flow through = white areas.
how would the PE resp lung scan differ to normal?
normal: even distributionm of radiopharma. uptake and can see outline of lungs
perfusion scan of PE: cant see outline.
mismatch. blockage blood + tracer cant flow through = white areas.
radiopharmacy can be used in the musculoskeletal system for the assessment of bone metastases secondary to which 2 types of cancer?
breast and prostate
name one other condition aside from bone metastases that can be diagnosed using radiopharmacy in the musculoskeletal system?
stress fractures
musculoskeletal system radiopharmacy has X sensitivity but X specificity. therefore you must…
High sensitivity but low specificity
Must undertake interpretation of scans with px history
An IV injection of 99mTc-medronate / 99mTc-oxidronate is given as tracer when assessing for bone metastases. How many hrs after this injection does the scan take place?
3
although clinical hx needed to interpret bone scans, what would the scans look like if metasteses are present?
uptake enhanced in active areas of bone growth seen as hot spots (darker than normal scans)
What is MPS (myocardial perfusion scintigraphy) with single photon emission computed tomography (SPECT) used to assess?
myocardial ischaemia in suspected coronary artery disease
(CVS radiopharmacy)
A MPS with SPECT involves an IV injection of 99mTc Tetrofosmin. Which cells does the uptake of this occur in?
cardiac muscle cells
what are the 2 parts at MPS with SPECT are performed in?
stress + rest (not necessary if stress scan is normal)
2 ways heart may be stressed by for MPS scan?
by exercise / pharmacologically (adenosine, dipyrimadole or dobutamine)
what does reduced uptake in MPS scans suggest?
Coronary stenosis/ damage
What are 2 uses for a MUGA (multigated acquisition scan)? other CVS scan
assess degree of HF
monitor effects of cardiotoxic drugs
2 CVS scans (use of radiopharmacy)
MPS w SPECT
MUGA
For a MUGA scan an IV injection of sodium pyrophosphate is given initially, followed by a IV injection of 99mTc. How many mins later is the latter given?
20-30 mins
which type of scan involves a camera that takes pictures at specific times during each heartbeat
MUGA
99mTc-HMPAO (Ceretec™) can be used to diagnose alzheimers, stroke and epilepsy. What do these conditions all have in common in relation to perfusion?
altered cerebral perfusion
Where does 123I-Ioflupane (DaTSCAN™) bind to dopamine transporters?
in the nigrostriatal dopaminergic system in the basal ganglia
2 types of CNS scan?
Ceretec
DaTSCAN
what can 123I-Ioflupane (DaTSCAN™) be used to differentiate essential tremor from?
parkinsons
what can 123I-Ioflupane (DaTSCAN™) be used to differentiate dementia with lewys body from?
alzheimers
what would abnormal DaTSCAN™ look like?
redcued uptake (transporters) so looks rounder not crescent shaped
what is 99mTc labelled with for a GI bleed assessment? + drawback?
RBC
only detected if bleed occurs during study
to investigate gastric emptying what can be coupled with 99mTc-colloid?
Food mixed with radiopharmaceutical:
scrambled egg or pancake.
to investigate oesophageal transit what can 99mTc-colloid be coupled with ?
soup
meckels diverticulum is a congenital defect which involves a bulge in the lower part of SI. Why does it -> ulceration + bleeding in small num of px with the disease?
cells from stomach and pancreas -> secrete acid -> ulceration and bleeding, can -> peritonitis if untreated
what would an IV injection of 99mTc-Mebrofenin be used for?
imaging of the biliary system and evaluating its function
as it binds w plasma proteins -> carried to liver -> hepatocytes take it up
Hepatic/ hepatobiliary system scan, what to do with liver transplant px?
part of liver removed and have to check will be effective before put in
What can 99m Tc-Mebrofenin be used for? 3
- Used for liver transplant patients
- Obstructive jaundice
- Biliary atresia
Hepatic/ hepatobiliary system scans show/ follow what?
Movement of bile through stages. Images taken at various intervals. Should and do see liver first = normal scan.
Must be surgically corrected else may lead to liver damage
which type of renal investigation uses 99mTc-DTPA (diethylenetriaminepentaacetic acid)?
GFR
which renal investigation uses 99mTc-MAG3 (mercaptuacetyltriglycine)?
renal perfusion
which renal investigation uses 99mTc-DMSA (dimercaptosuccinic acid)?
renal parenchymal function
in addition to the agents and tests which form part of radiopharmacy, what would the addition of furosemide or captopril in diagnostic testing be used to investigate for?
renal vascular hypertension and renal obstruction
What should happen after a radiopharmaceutical tracer has been injected?
The kidneys should be able to excrete the tracer hence activity eventually goes down
However, those with obstructions mean that kidneys can’t excrete them so they remain elevated
(image p5)
after a radiopharmaceutical tracer has been injected, what could be given to help excretion if kidneys not excreting activity?
(obstructive/ nor response)
furosemide
after a radiopharmaceutical tracer has been injected AND given furosemide.
what does it mean if kidneys
- still dont excrete tracer
- do excrete
If still don’t excrete after furosemide = obstruction., if they do = dilated renal system. Response to diuretic.
what scans are commonly used in children who’ve had UTIs… could -> scarring of kidneys
DMSA scans
DMSA scans used to check what?
structure any changes in size / shape
Can show areas of kidneys that are working well and which show scarring
if normal,= normal equal and even uptake
Are these agents : 99mTc or 123I used to image the thyroid or the parathyroid gland?
in endocrine system
thyroid
are these agents: 99mTc Sestamibi and 123I used to image the thyroid gland or the parathyroid gland?
in endocrine system
parathyroid
WBC labelling is useful in the diagnosis of infection of an unknown origin and can be labelled with 99mTc HMPAO or 111In. Name two diseases that this method would be used in the assessment of ?
crohns disease and ulcerative colitis
WBC labelling for infection + inflammation process?
Isolation of white cells radiolabelling re-injection with cells tagged with radiopharmaceutical. Scan for uptake = infection
Malignant disease: the 4 radiopharmaceuticals and isotopes used
99mTc Nanocolloid
123I mIBG
111In Octreoscan
68Ga DOTA-TOC
for malignant disease. the radiopharmaceutical: 99mTc Nanocolloid is used for?
breast cancer and melanoma
(determine extent of lymph node involvement in)
for malignant disease. the radiopharmaceutical: 123I mIBG use?
(use declining)
Extra-adrenal phaechromocytomas
for malignant disease. the radiopharmaceutical: 111In Octreoscan use?
somatostatin receptor tumours
but Ga used more: better imaging
for malignant disease. the radiopharmaceutical: 68Ga DOTA-TOC use?
neuroendocrine tumours PET radiopharm.
whats the sentinel node? (malignal disease breast cancer scans)
1st lymph node in drainage pathway of the tumours and undertaken before surgery to aid excision of tumours.
Used for sentinel node localisation in breast cancer and melanoma px
in Octreoscan, liver kidney spleen bladder show as dark areas. what does this mean in THIS scan?
Look like hot spots BUT this is a normal scan presentation.
gold standard for diagnosing/ imaging neuroendocrine tumours?
68Ga
4 radiopharmaceuticals used for therapeutic applications?
- 223Ra dichloride
- 177Lu-DOTATATE
- 131I mIBG
- 90Y SIR-Spheres microspheres
Castration-resistant prostate cancer with symptomatic bone metastases
+
Alpha radiation directly to bone metastases to relive pain
describes therapeutic application of which radiopharmaceutical?
223Ra dichloride
- PPRT - Peptide receptor radionuclide therapy
- Gastro-enteropancreatic neuroendocrine tumour
- IV infusion of AA before treatment to protect kidneys
describes therapeutic application of which radiopharmaceutical?
177Lu-dotatate
- Malignant phaechromocytoma
- Carcinoid or medullary thyroid carcinoma
(but use is declining)
131I mIBG
- Malignant phaechromocytoma
- Carcinoid or medullary thyroid carcinoma
(but use is declining)
describes therapeutic application of which radiopharmaceutical?
131I mIBG
- Selective internal radiation therapy
- Inoperable hepatocellular carcinoma
describes therapeutic application of which radiopharmaceutical?
90Y SIR-Spheres microspheres
How are 90 Y SIR-Spheres microspheres implanted into the body?
Via the common, left or right hepatic artery
90Y = a high energy pure beta-emitting isotope., therefore what must be done before 90 Y SIR-Spheres microspheres implanted into the body?
Before treatment – determination of lung shunt %.
what px is 90 Y SIR-Spheres microspheres treatment contraindicated in?
In patients with lung shunt >20%/ hepatic artery block
what is px injected with if have more than 20% shunting/ hepatic artery block and cant have 90Y SIR-sphere microspheres treatment?
Technetium bound MAA to assess arterial perfusion of the liver -> identify fraction of the tracer that will lodge in lungs.
Very important as excess shunting can -> radiation pneumonitis
L Drug interaction with radiopharmaceuticals
Drug Interactions
* Advantage
* Disadvantage
- enhance nuclear med investigations
but - can adversely interfere with nuclear medicine investigations
Altered pharmacokinetics and/or pharmacodynamics may result in …
a WRONG diagnosis
123I-Ioflupane (DaTSCAN™) is a cocaine analogue. medicines with a high binding affinity for which transporter can interfere with the study of this radionuclide?
dopamine
Do Dopamine agonists/antagonists acting on the post-synaptic receptors cause any issues (i.e. medicines for Parkinson’s disease) when using 123I-Ioflupane (DaTSCAN™)?
no
What 4 medicines classes can disrupt the scan for diagnosis of tremor or Parkinsonian syndrome? (DaTSCAN)
Medicines that bind with high affinity to dopamine transporter will interrupt 123I-ioflupane:
- SSRIs
- CNS stimulants
- Anxiolytics
- Sympathomimetics
name an SSRI which may increase or decrease the binding of 123I-Ioflupane (DaTSCAN™)?
sertraline
the following : amphetamines, methylphenidate, modafinil may increase or decrease the binding of 123I-Ioflupane (DaTSCAN™). What drug class do they belong to?
CNS stimulants
name an anxiolytic which may increase or decrease the binding of I-Ioflupane (DaTSCAN™)?
buspirone
the following : pseudoephedrine, phenyephidrine and ephidrine all increase or decrease the binding of I-Ioflupane (DaTSCAN™). What drug class do they belong to?
sympathomimetics
why must opioid analgesics be stopped before hepatobiliary imaging?
they constrict sphincter of oddi increasing the pressure in the common bile duct
stop at least 24h before
why must nifidepine be stopped before hepatobiliary imaging?
alteration of gallbladder motility
what effects might beta blockers have on the response to excercise induced stress for cardiovascular imaging?
blunt response -> false negative results
name 2 rate limiting CCBs that interact with CVS imaging and could lead to false negatives?
diltiazem and verapamil
are dipyridamole and ivabradine appropriate to be taken when having a CVS imaging investigation?
no
when a patient is having CVS imaging should abstain from tea, coffee and soft drinks 12 hrs before. why?
due to the caffeine content.
So when px being studied at rest, must be no other interactions stimulating the heart which enables heart to only be stressed when required for the diagnosis
what drugs may interact w thyroid imaging and therapy?
Any drug that interferes with the uptake of iodine, or blocks its release from thyroid -> may lead to misdiagnosis
list the drugs that may affect thyroid imaging and therapy
thyroxine, amiodarone, cough medicine, antihistamines and corticosteroids
food containing iodine eg seafood
why should Carbimazole and propylthiouracil be withdrawn one week before radiotherapy for the thyroid gland?
(hyperthyroidism)
inhibit metabolic synthesis of thyroid hormones and decrease uptake of radioiodine
prior to investigation interacting drugs should ideally be stopped for how many half lives?
5.5
Specialist clinicians must be consulted when withdrawing meds prior to investigation, esp for antihypertensives and antipsychotics. why?
If withdraw= deterioration of underlying condition, not justifiable
what drugs can be used to induce cardiac stress for MPS?
adenosine, dobutamine and regadeson
which drug to induce cardiac stress for MPS is the most appropriate for asthmatic patients?
dobutamine
how is Adenosine gievn to induce cardiac stress?
IV given then tracer after 4 mins of infusion, adenosine continued for 2 mins. Half-life 13 seconds.
main aim of Adjuvant medicines in renal imaging?
distinguish between dilated, non-obstructed urinary tracts from those with significant mechanical obstruction
if renal obstruction is not corrected (surgically) name one condition that it can lead to?
renal atrophy
what effect will the admin of furosemide have on a dilated and non obstructed renal system?
washout of activity
what effect will the admin of furosemide have on a dilated and non obstructed renal system?
washout of activity
what effect will furosemide have on an obstructed renal system?
accumulation of activity after admin
what is the most common cause of secondary hypertension?
renal artery stenosis
what is renal artery stenosis?
Constriction of efferent arteriole -> maintenance of perfusion pressure in the kidney
which drug would be the most appropriate to be used an adjuvant medicine in renal imaging for the detection of renal artery stenosis? + what does it do?
captopril
fall in perfusion pressure -> decrease in GFR
how is renal artery stenosis diagnosis made?
by comparison of baseline study with a captopril enhanced study
all opioids should be stopped at least 24 hrs before investigation of sphincter of oddi dysfunction. However, which drug can be used as an adjuvant provided the dose is sub therapeutic?
morphine
other than morphine, what other/ less common drug may be given as adj med in hepatobiliary imagine?
phenobarbitone
what is the rationale behind giving a patient a fatty meal when investigating for functional gall bladder disorder?
induce gall bladder contraction and emptying
DaTSCAN™ & mIBG requires the admin of X prior to investigation?
KI potassium iodide
why is a thyroid blockade with potassium iodide needed prior to a DaTSCAN™ & mIBG?
Free radioiodine (123I) released during degradation of radio-iodinated compounds, taken up by the thyroid
thus thyroid blockade w KI needed as…
Works by blocking thyroid gland from absorbing radioactive I and thus protects it from damage that can result from absorption of free radio iodine and reduce risk of any possible thyroid cancer
- Duration of blockade depends on the dose of the diagnostic/therapeutic radiopharmaceutical
177Lu-dotatate (Lutathera)- Treatment of neuroendocrine tumours and emits beta rays after binding to which receptor?
somatostatin
why is a Amino acid solution (L-Lysine and L-Arginine) infusion initiated 30 mins prior to lutathera and continued during admin and at least 3 hrs afterwards?
protect kidneys as L emits beta rays and is renally excreted
3 roles of a radiopharmacist?
- Preparation of lists of interacting medicines
- Advising on new/ unusual medication
- Reporting unusual biodistributions/ interactions
