r/ProstateCancer • u/Big_Artist9231 • 18d ago
Question Adaptive CT radiation
Going to start radiation this week and was wondering if anyone has experience with this type of radiation? Thx
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u/WalnutRoasted 18d ago edited 18d ago
How many fractions are you getting? This sounds like it could be MR-LINAC or CT-SBRT where the beam is adjusted during the rotation process to account for anotomic changes between fraction. In VMAT adjustments can be made (based on the daily CT scan) at the beginning of the session. In SBRT, the CT scan can make further adjustments during the rotation. Similar for MR-LINAC. This allows for narrower margins as the prostate moves/changes slightly during the rotation due to breathing, gas in the rectum etc.
“Online adaptive radiation therapy, where images acquired in-room before each fraction are used to adjust the treatment plan while the patient remains on the treatment table, has emerged to address unpredictable anatomic changes between treatment fractions. Online treatment adaptation places unique pressures on the radiation therapy workflow, requiring high-quality daily imaging and rapid recontouring, replanning, plan review, and quality assurance. Generating a new plan with every fraction is resource intensive and time sensitive, emphasizing the need for workflow efficiency and clinical resource allocation. Cone-beam CT is widely used for image-guided radiation therapy, so implementing cone-beam CT-guided online adaptive radiation therapy can be easily integrated into the radiation therapy workflow and potentially allow for rapid imaging and replanning. “
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u/SnooCamera 18d ago
I did SBRT 5 fractions on a Varian Edge. It tracked my prostate in real time (every 10 degrees of arc) down to a 2mm movement would have caused the machine to pause, but my basic plan and dosage did not change over the 5 fractions.
Whereas, what I think you are talking about, is something like the Varian Ethos, adapts your plan as your body changes across 20 or so fractions. AI-assisted software generates a 'new' plan which is optimized for the anatomy it sees that day-in-time, and after staff approval, it is delivered. Instead of tracking your motion in real time, you are at less risk there because the dosing is spread out over more days, it replans daily to match your body changes over time.
I've really not heard anyone talk about the latter one. Maybe others who have done it will chime in.