Scintigraphy Flashcards
how does nuclear scintigraphy work?
Radioisotopes are administered to the body as radiotracers
cell activity attracts the radiotracer
- higher activity/cell turnover = high uptake
- eg tumours or hyperactive thyroid
when isotopes then decay energy is released as gamma rays
- this is used to read radioactivity from scans and create an image
why use scintigraphy?
highly sensitive to small changes within the body
help identify/locate:
- tumours
- fractures,
- abnormal organ function
- tissue damage
- bone changes
very useful with hyperthyroidism
- uses iodine 131
- allows to identify and monitor
- also shrinks thyroid cells
what are the properties of iodine 131?
half life = 8 days
- patients radioactive for a long time
- hospitalised for 12-15 days
gamma energy = 356 keV
- hight radioactive energy = high risk
- but does allow for thyroid cells to be killed
how should you manage the half-life of radioactive isotopes?
waste management
- eg needles, equipment, bedding etc
- all put into dedicated area/box
- either lock away until no longer radioactive - then remove in general waste
- or have paid to be taken away as radioactive
patient management
- hospitalise for 12-15days
- avoid as much as possible
- have everything beforehand (eg extra food/water/bedding)
- signposted radioactive area
what safety precautions need to be considered when handling radioactive isotopes?
regulations
- practice process - record of doses, drugs and waste
- Radioactive Substances Act of 1993 - licenses to remove - often pass onto courier companies
handling of isotope
- set protocols to manage product - from drawing up to waste management
- using lead shielded glass (pane of glass lead lined between you and dose)
- draw up into a tungsten-lined syringe - don’t waste any!
- wear a dosimeter, gloves and change clothing and isolate once used
- if gets on you - tell someone and record
- no food or drink around
what are the components of a scintigraphy camera? what are their functions?
Collimator
- streamlines gamma from patient to crystals
- prevents oblique images
NaI (TI) crystals - Thallium Activated Sodium Iodide Crystals
- convert gamma into light
Lucite light guide and Photomultiplier tubes
- steams light to amplifiers
Amplifier
- light is amplified into different strengths
- identifies differences in signals and amounts
Data analysis computer
- analyses different strengths which is then displayed
what maintenance is needed for a scintigraphy camera?
temp control
- 24-27 degrees
- changes cause internal pressure which can damage crystals
protect against power surges
- have on genererator
- protects from powercut
calibrate and service annually
check for damage
- machine itself and image quality
what is a Geiger counter? why do we use it?
used for our safety and stops contamination of radioactive material to staff and around practice
- takes readings to identify spillage of radioactive material and its level
- measures if over limit and alerts
when to use:
- identify possible spills or check that area used is safe
- if patient urine spills around the practice
- check objects safe for waste
- check if the patient ready to end hospitalisation
- check if on clothing after being with the patient - avoid moving around
how should you prepare a patient for scinitgraphy?
GA/Sedate - starve and catheter
make sure bladder is empty
- once given an isotope body will try and remove via urine
- if not emptied will fill up quickly
- all will see is the bladder on image
if bone scan (uncommon)
- patient needs higher temp for better uptake
- done by increasing circulation
if for thyroid
- inject SC and wait 20mins for uptake
howto reduce risk during scintigraphy scanning?
low risk due to the short time taking an image - approx 3mins
use plastic aprons and shoes to reduce the risk of contamination
then keep distance from the patient as much as possible
what are the advantages and disadvantages of scintigraphy?
Positive
- provides instant feedback
- allows for monitoring and treat hyperthyroidism
- allows for identifying high tissue activity/tumours
- very sensitive to small changes in body
disadvantages
- radioactive - gamma hard to manage
- long hospitalisation needed - price and stress
- waste management - space/price
- supply issues
