Gamma Knife Flashcards
What are the 4 main features of radiosurgery?
- single high dose (12-150Gy)
- tissue ablation/destruction
- requires defined target
- typically for targets less than 3-4cm
What lesions are treated with GK?
- meningioma
- brain mets
- trigeminal neuralgia
- acoutis neuromas
- arteriovenous malformations
- pituitary lesions
What are the clinical indications for meningioma GK?
- slow growing
- dose is 12-20Gy
- control rate 90% at 5yrs
What are the clinical indications for brain mets GK?
- avoid complications with WBRT
- improved QOL
- dose 15-22Gy
What are the clinical indications for trigeminal neuralgia GK?
- most severe pain syndromes
- medical management fails patients require surgical intervention
- GK less invasive usually older patients
- dose 75-90Gy
What are the clinical indications for acoustic neuromas GK?
- slow growing, benign usually from vistibular portion of 8th nerve
- unilateral hearing decline
- dose 12-13Gy
- 93-100% control
What are the clinical indications for ateriovenous malformations GK?
- goal is complete obliteration
- reduce lifetime risk of hemorhage to 1% or less
- dose 18Gy in 1#
What are the clinical indications for pituatary lesions GK?
- good for reccurent or residual nonfunctional pituitary adenomas
- GK high tumour control and reasonable rate of endocrine remission in patients with Cushing’s disease
- dose 15-26Gy
What are some features of a GK bunker?
- staff swipe access in and out of patient waiting and maxe door
- after treatment hrs area past maze dorr is alarmed and locked by key
- treatment door locked when not in use
What is the MDT workflow for GK?
- statewide servie
- MDT team (neursurgeons, RO, RT, physcisits, nurses, MI and allied health)
- weely MDT meeting
- weekly MDT clinic
- treatment day
What happens on treatment day for single fraction patients?
- frame attachment
- planning CT
- planning MRI
- treatment plan
- QA
- treatment
- frame removal
- discharge
What does the radiation unit include for GK?
- collimator system
- 192 60 Cobalt sources
- two gamma rays (1.17 Mev, 1.33 MeV)
- shielding
- shielding doors
What is the half like of 60Co and how often does it need changing?
- 5.25 yr half life
- change every 5 years
What is the imaging process?
- frame provide spacial references and immbolises the patients head
- patient scanned with an indicator box in place
- reference fiducials during image acquisition
- creates the stereotactice space for each image
- images sent directly to gamma plan via dicom
How does gamma plan define images?
- fiducial markers are defined for each image imported into gamma plan
- creates the sterotactic space
- leksell coordinates on the image for placing treatmen shots
