BONE SCANS Flashcards
what sed rate is needed to classify as a bone infection present??
greater than 70
short arthropathy
arthritis tht causes bone looss, difficult to distinguish from osteomyelitis
what is radioacative isotope’s physical 1/2 life?
-amount of time it takes for 50% degradation of the radioactive isotope
what is the radioactive isotope biological 1/2 life
amount of time it takes for 50% of the isotope to remain in the organism before excretion
what is an ideal radionucleotide?
- minimum particulate emission
- photon energy 50-500 Kev
- physical 1/2> prep time
- Bio 1/2 life> exam time
- low toxicity
- stability
- suitable chemical form for study of the specific organ
tech 99
-rapid osteoblastic medicated chem abs on surface of hydroxy appetite
-physical 1/2: 6hrs
photon energy 140KeV 90%
-trauma-> inc osteoblast activity-> increase hydroxy appetite at location
the 3 phases of diagnostic study of bone scans
I: 3sec, dynamic or blood flow phrase, angiogram
II: 3min, blood pool phase or tissue phase
III: 3 hr, delayed imagine of bone imaging phase
IV: 24hrs delayed phase caused by people w/ vascular insufficiency
Gallium 67-citrate
bone scan used for infections, neoplasm, cancer stuff, inflammatory disorders
-less dependent on blood flow
-photon energy emitted:
94KeV 40%
184KeV 24%
296 KeV 22%how does gallium localize stuff
-leukocyte localization
-lactoferrin/ transferrin binding/ siderophores of bacteria
-1/2 78hrs
slow rate of excretion
when are galium images perfromed?
- 6-24 hrs post injection for infection
- 24-72 hrs post injection for neoplasms
Indium 111
-oxine labeled white blood cells
-binds to cytoplasmic component of WBC membrane
-dependent on chemoraxis of leukocytes
-1/2 life 67hrs
-photon energy emitted
173KeV 89%
247 keV 94%
Cretec
- Tc99 labelled WBC
- increased specificity for infectious process
- photon energy emitted 140keV 88%
Sequestrum
dead necrotic bone separated from affected bone
