Respiratory Motion Management Flashcards
ITV and same with abdominal compression
1.CT SCANNING APPROACH
2.VOLUMES DELINEATED
1.-4DCT REQUIRED
-3D dataset generated from (MIP) to help delineate the ITV
2.ITV =account for motion throughout
breathing cycle
PTV = margin added to ITV to account
for geometric uncertainties
Respiratory Gating
1.CT SCANNING APPROACH
2.VOLUMES DELINEATED
- same as ITV
- -TV to account for motion in a specific phase
-margin added for geometric uncertainties
DIBH
1.CT SCANNING APPROACH
2.VOLUMES DELINEATED
1.4DCT not required
CT acquired in Breathhold
2.GTV and CTV delineated based on tumour in breathhold scan.
PTV for margin for CTV
ITV ADVANTAGES
Less resource intensive – easy to implement
* No patient input required – patient breathes normally
ITV DISADVANTAGES
Increased NT irradiated
* Assumes reproducible, predictive breathing patterns
* Tumour motion may change between planning and. delivery
Respiratory Gating ADVANTAGES
*Smaller ITV – less normal tissue irradiation
*patient breathes normally
Respiratory Gating DISADVANTAGES
- Can be difficult to implement – QA, etc
- Longer treatment times
DIBH ADVANTAGES
- Easy to implement. 3DCT facilities not required
- Stalls tumour motion –reduced target volume
DIBH DISADVANTAGES
- Significant patient cooperation needed
- Increases treatment time
Abdominal Compression ADVANTAGES
Very effective at reducing motion
limitations of 4DCT
-Increased Imaging Dose: requires multiple projections of the different respitatory phase tf higher rad expo (2-5x the dose)
-Longer Acquisition and Processing Time: longer to acquire and recon images …. affect workflow efficiency and patient comfort (4 minutes vs 1-2 minutes)
-Motion Artifacts and Image Quality : Respiratory irregularities can cause artifacts and blurring in 4D CBCT images, reducing the accuracy of tumour delineation and motion assessment
strengths of 4DCT
-Improved Tumour Localisation:
- reduced PTV margins
