Nuclear Med Flashcards
what are the types of targeted radionuclide therapy
radionuclide itself
radioimmunotherapy: monoclonal antibodies
radio labelled microspheres: introduced into arterial circulation od tumours and provides localised radiation
small molecules which carry radionuclide
malignant pheochromocytoma
highest incidence 30-50
hereditary diagnosis: 24.9 years
sporadic diagnosis: 43.9 years
25% is hereditary
what are the symptoms for malignant pheochromocytoma
high blood pressure
headaches
sweating
forceful palaptations
temor
facial pallor
MP, NETS have:
specific receptors at membrane
specialist neuroamine uptake mechanisms
In the adrenal medulla, some cells produce catecholamines. MIBG concentrates in the secretory granulose of the cells. Tumours which produce catecholamines are eager to metabolise this
High doses of I-131, MIBG are used
what does PRRT used
radioactive labelled analogue therapy
what is the physiology of the RSAT
somatostatin is a hormone in the body, which binds to receptors which slows down hormone production, controls gastric and bowel emptying
if there is an abnormal increase treatment might be suitable
must be symptomatic with unresectable or met progressive disease
what is the treatment for PRRT
as some NETS overexposes surface receptors, the somatostatin analogue is taken, the radionuclide with a beta radionuclide. A therapeutic dose must be delivered to the tumour
Yttitrium-90 and Lu-177 most common
what does SIRT stand for
selective internal radiation therapy
SIRT
for primary and secondary inoperable tumours in the liver
last resort
normal liver draws 80% of blood from portal vein
tumours draw more than 80% of their blood from the hepatic artery
what is TARE
Trans-arterial Radioemoblisation
who is TARE for
functioning live with a primary unresectable tumour, HCC
not suitable for TACE
secondary liver tumour with colorectal injury
options discussed in MDT
selected by hepatobillary cancer MDT
what happens during the planning angiogram for SIRT
takes 1-2hours
identify blood supply to the liver
local anaesthetic
contrast injected
small blood vessels are blocked so the microspheres can be located
150MBq radioactive tracer [Tc-99] injected into the catheter
SPECT-CT picks up the radioactive tracer, locating the liver
recover overnight in hospital
what happens after the planning angiogram
1-2 weeks after it is repeated
when the catheter is in the liver the microspheres are injected in which takes approx 1 hour
catheter is removed and wound is dressed
pain meds and antiemetics
scan checks the beads
what are the SE for SIRT
nausea
abdominal discomfort
chills
raised temp
stomach pain
diarrhoea
fatigue
cholecystitis: pain, nausea, fever
microspheres in lung = cough and SOB
microspheres in GI tract = nausea, pain, pancreatitis, stomach ulcer and bleeding
hazards with SIRT
wash hands thoroughly
avoid contact with pregnant women and children for the first week after
sleep alone for first 1-2 nights
microspheres remain in the liver
CT scan 2-3 months post treatment
regular liver and kidney tests
what is refractory myeloproliferative disease/ PRV
over production of RBC, uncommon in bone marrow
what are the symptoms of PRV
hyper viscosity
headaches
dysponea
blurred vision
sweating
weightloss
2/3 have enlarged spleen
pruritis
flushed complexion
anaemia due to poor flow
where is PRV seen
50-60
male
main cause of death is haemorrhage, or thrombosis, due to increased blood flow
raised RBC increases WBC and platelets
median survival: 9-13 years
if not treated 50% die within 18 months
what is the treatment for PRV
venesection: one pint of blood is taken at regular intervals, repeated at 24 hours and then 48 until packed cell volume <0.5 [temporary solution]
Chemo- chlorambucil or busulphan (every 4-6 weeks)
P32: sodium phosphate
describe P-32 as a treatment option
neutron irradiation of P-31
half life = 14.3 days
emits beta particle: 3-8mm range
decays to non radioactive sulphur
usual dose = 150-250MBq
initial dose = 74-111 MBq
further treatments = max 260MBq
where is there rapid uptake of P-32
in rapidly dividing cells
it is selectively uptakes into haemopietic tissue
it is incorporated into DNA of rapidly dividing cells
what does P-32 inhibit
marrow, therefore blood production
highest conc is in bone marrow and trabecular
administration of P-32
oral or IV
syringe has perspex casing for shielding
20 minutes through butterfly to avoid extravasations
check circulation
average response time is 7 days
administrator must wear film badge, gloves, mask etc
caution with taking a blood sample as it will be radioactive
effective dose is 465mSv
what are the hazards of P-32 sodium phosphate
long term will cause leukaemia in 10-15%
GI absorption causes symptoms similar to irritable bowel
don’t give to pregnant, breast feeding women and children
clinical applications for unsealed sources
orally via capsule
radioactive gas
IV
nuclear med
diagnostic imaging: diagnosis or localisation
in vivo studies: patient injected with radioactivity samples taken to measure the level in blood, urine and faeces
in vitro: in glass, radioactivity is injected into blood, faeces and urine outside the body i.e radioimmunoassay uses antibodies to detect and quantitate the amount of an antigen
treatment: molecular RT or radio-immunotherapy
how is a tumour localised
- a pharmaceutical is elected which will seek out the tumour
- label the pharamacuetical use a radionuclide which won’t interfere with the uptake of the pharmaceutical but allows for easy detection
- detects the pattern of distribution of gamma rays emitted by the radiopharmaceutical with a gamma emitter
- use the smallest activity practicable to minimise hazard, as staff will be irradiated
advantages with localising
looks at function and position
disadvantages with localising the tumour
limited to small masses <10mm in diameter, if larger multiple treatments might be needed
location is hard to define
diagnostic: gastric
looks at motion of food through the oesophagus into the stomach and its transit time
water, eggs, toast and Tc-99M
ant and post dynamic images at regular intervals for up to 4 hours (stomach emptying takes 3/4 hours)
draws ROI around stomach, GI tract and creates decay corrected curves for activity