Head and Neck Lec 3 Flashcards
What are some first day considerations
- Chemotherapy - timing and the shell fit
- Teeth removal
- Prophylactic tube insertions NG tube or PEG
What are some of the imaging/s seen for H.N ?
- Cone beam
- KV
- MVCT (megavoltage CT) – used in tomo
- EPI
- Hard copy film
How has imaging changed in AUS?
- Used to base everything on EPIs in the past
- Now we have upgraded the linacs we are seeing a lot more KV and volumetric imaging
- This new imaging has had a significant impact on the H/N field.
Where EPIs are concerned, why would you take an orthogonal image over an oblique set of images?
- because oblique set of images may not give the true translation.
What are the advantages of EPI? (5)
- good soft tissue
- Easy
- Fast acquisition
- Easy storage
- Makes online correction feasible
What are the disadvantages of EPI? (3)
- Poor image quality
- Cant see detailed structures
- Hard to visualise structures.
What is the amor advantage of KV imaging?
- Increased image quality and definition of structures, particularly bony anatomy (which is good for the H/N).
What are the advantages of CBCT for H/N patients?
- allows us to see separation and rotation
- better patient positioning
- more effective immobilisation
- allows us to use new tx techniques
- allows us to see volumetric tissue comparison.
What affects a CBCT length of image acquisition and quality?
-The use of collimation and filters
What type of images are used in tomotherapy?
MVCT
- these images take 2-4 minutes to acquire and mimic a ct scan.
- dose distribution can be checked via quick calculations which is telling of whether a pt needs a rescan.
- not as good of quality as KV
What are the 3 domains of isocenter verification
1 - software matching methods
2- anatomical match points
3- verification tolerances
What is software matching methods?
- can be very basic e..g using the measurement tool to measure between different anatomical structures
- may have image overlay/ template matches
- provides disp. measurement in 3 planes (a/p s/i and l/r)
What are the domains of CBCT matching?
- Soft tissue matching, bony matching and manual tools.
- RO can set a clip box and lock to the most critical area.
What are some of the tools used for CBCT matching
- spy glass
- checker board
- image cut
- image fusion
- structure overlay on localisation points.
How does the displacement provided differ between CBCT and KV imaging? (what plains)
KV - only 3 plains CBCT - 6 cartesian plains - ap - lr - si - pitch - roll - yaw.
What are some match points for H/N
- CV1-2
- CV 2-5
- Clivus
What is another name for verification tolerance and what does this depend on?
Aka. action level.
Depends on;
- inherent accuracy of the linac
- conformability of the plan
- accuracy of the immobilisation equipment
What is the action level for H/N treatment?
- usually around 3mm
- this allows 2mm for the linac tolerance
- also is achievable using immobilisation devices.
What do you do when nothing matches on an image?
- best fit
- match to the critical points
- reset the patient.
DONT do nothing
What would you do if a shell was spacey and generally not fitting?
- could indicate the need for a re-plan
- put gel behind the head
- take an MVCT/ CBCT/ CT to see what effects this will have on the plan.
- talk to a dietician
- flag people early
What are some of the less common acute side effects?
- reddened patches within the mouth
- swelling
- bleeding from gums
- husky/ raspy voice
- furry tongue
- dry cracked lips
Advice to patient suffering from a sore mouth? (7)
- Eat soft bland foods
- Avoid really hot and cold foods
- brush teeth with a soft tooth brush and mild tp
- carry a drink bottle
- rest voice
- take ‘pink lady’ (zylocane) to numb pain of eating.
- regular mouth washes using bicarb/salt
What would you do if the patient has dysphagia?
Notify medical and nursing staff
Advice to a patient suffering with a dry mouth and thickened salvia? (6)
- carry a spray bottle
- drink soda water and rinse mouth with water
- use dry mouth gel
- maintain good oral hygiene
- decrease coffee, alcohol and smoking
- drink lots of water.
What would you advise/ do for a patient who is having trouble with nutritional issues.
- don’t drink alcohol (bc it can further irritate the mouth lining)
- see a dietician
- eat protein rich foods to maintain weight
- may need a nasogastric tube or EPG>
What would you advise a patient so they maintain good skincare throughout treatment? (12)
- avoid friction and pat dry
- do not use sunscreen in the area or makeups/cremes
- do not use perform/ talc in the area
- avoid really hot and cold water
- wash hair with baby shampoo
- shaving only to be done using an electric razor.
- avoid sun exposure (wear protective clothing)
- keep area clean and dry
- warm water unscented soaps.
- apply moisturising cream to the area (aqueous)
- wear loose clothing
- notify staff of itchy/broken skin
What would you advise the pt (in regards to skin care) upon completion of treatment? (5)
- continue gentle skin care
- wait until full healed to e.g. blade shave again
- Ros and nursing staff will tend to bad reactions after tx completed
- need to protect the area from the sun for the rest of life
- late reactions could mean a thickening of the skin and a change in the pigmentation.
What are some side effects that may directly affect tx ?
- Weight loss (dose change, decreases shell immobilisation )
- Skin reaction (pt may not be able to get into position)
- General well-being (affects tx compliance)
