Advanced TP Flashcards
1
Q
What are the two types of motion?
A
- physical: respiration and cardiac motion (systematic)
- violitional: swallowing and couhing (random)
2
Q
What is intrafraction motion?
A
- movement of patient during a single fraction
- main focus of 4D applications
- 4DCT
3
Q
What is inerfraction motion?
A
- motion between fractions
- organ filling/emptying variations
- adaptive therapy
4
Q
What are the benefits of controlling motion?
A
- tumour margins decreased
- OAR sparing
- potential dose escalaiton
- improve clinical outcomes
5
Q
What are some motion management solutions?
A
- vacbag
- breathing control (ABC, RPM, compression belt)
6
Q
What is 4DCT?
A
- aquisition of multiple images at slice positions, each tagged with breathing signal
- images are sorted based on breathing signal
7
Q
4D vs 3D imgaing?
A
- 4D allows full tumour trajectory tracking
- 3D gives partial tumour trajectory (inspiration, expiration)
8
Q
What is MIP?
A
- maximum image projectory
- displays the max no. of all pixels at the same locatin over the respiratory cycle
- shows entire extent of tumour motion
- caution for tumour close to diaphragm and chest wall
9
Q
What is MinIP?
A
- minimum image projectory
- displays the min no. of all pixels at the same sptial location over the respiratory cycle
- shows where some of the tumour always is
- useful for liver tumours that present at low density
10
Q
What is AvgIP?
A
- average image projectory
- displays the avg no. of all pixels at the same sptial location over the respiratory cycle
- considered appropriate for planning which reduces the need for additional scan and thus dose
11
Q
What is MLC interplay?
A
- relationship between the leaves and target
- in normal treatment the effect is averaged out over 30 fractions, but with one fraction the clinical outcome of inteplay could be huge
12
Q
What is the benefit of variable dose rate?
A
- decrease dose rate and increase linac when going through OAR and increase dose rate and slow linac when going through tumour
13
Q
What is a specialty Image Set?
A
- feature that combines 2 or more image sets to make a specialty image
- e.g. MIP, MinIP, AvgIP
