Topics:
Radiation Oncology • Gastrointestinal Cancers
Do you allow your CTV expansion to go into lung for IMRT esophagus cases or do you crop CTV expansion out of lung?
The CTV examples in the contouring guideline by Wu et al (https://www.ncbi.nlm.nih.gov/pubmed/26104943) don't appear to crop the CTV out of lung. Would it be prudent to do so since invasion into the lung parenchyma could be considered unlikely? How does interfraction anatomic variability or set up uncertainty factor into the way you do your expansions?
Answer from: Radiation Oncologist at Academic Institution
This is an excellent question and to be frank, the panelists that formulated the 2015 guidelines I authored did not consider this issue explicitly, hence the implication that lung should NOT be cropped out of the CTV. I certainly agree with the comments above that the lung per se is unlikely to repr...
Sign in or Register to read more
Answer from: Radiation Oncologist at Community Practice
Many, many protocols do not understand GTV/CTV/PTV and certainly many in the past were not easily able to understand block edge to ICRU conversion. i.e. - GBM used to be treated with 2cm block margin, while the initial RTOG protocols with 3D/ICRU planning had volumes that were substantially larger. ...
Comments
Radiation Oncologist at Bon Secours Mercy Health
Dr. @Simul Parikh is indeed correct. Unfortunately...
Dr. @Simul Parikh is indeed correct. Unfortunately...
Answer from: Radiation Oncologist at Academic Institution
I do not expand CTV into lung - CTV represents at risk areas for microscopic disease which does not include lung parenchyma.
Final target volumes do include lung due to ITV (we use 4DCT for distal esophageal tumors) and PTV (0.7 cm, which is not edited). Ditto for heart.
Answer from: Radiation Oncologist at Community Practice
It's the year 2021. It's been many years since the ICRU defined what the CTV and PTV are. We should follow their definitions accordingly regardless of any bad habits we learned earlier.
If there's no risk of cancer in a voxel, it shouldn't be included in a CTV. If we're worried about setup uncertai...
Answer from: Radiation Oncologist at Academic Institution
I agree that the distinction between GTV/CTV/ITV/PTV can be blurred. I generally NEVER expand CTV across anatomic boundaries for mobile tumors in the chest. For example, I do not expand CTV out of the mediastinum around a level 6 node, or around the esophagus. If a lung tumor adjacent to the chest w...
Answer from: Radiation Oncologist at Academic Institution
I do not expand CTV into the lung - the lung is not at significant risk for tumor involvement. There, of course, should be a PTV expansion to account for uncertainties.
Comments
Radiation Oncologist at 21st Century Oncology
For the esophagus CTV, I do not expand the CTV int...
For the esophagus CTV, I do not expand the CTV int...
Answer from: Radiation Oncologist at Community Practice
Especially in the situation of esophagus cancer, the mobility of the (particularly lower) esophagus across a course of 23-28 fractions cannot be absolutely assured on the basis of one 4D simulation acquisition. The same can be said for lung tumors in which lung volumes can change. There needs to be ...
Comments
Radiation Oncologist at UCLA | VA Greater Los Angeles Healthcare System
It is my understanding that this approach violates...
It is my understanding that this approach violates...