Markerless liver online adaptive stereotactic radiotherapy: feasibility analysis

Phys Med Biol. 2024 Apr 2. doi: 10.1088/1361-6560/ad39a1. Online ahead of print.ABSTRACTObjective 
Radio-opaque markers are recommended for image-guided radiotherapy in liver stereotactic ablative radiotherapy (SABR), but their implantation is invasive. We evaluate in this in-silico study the feasibility of cone-beam computed tomography-guided stereotactic online-adaptive radiotherapy (CBCT-STAR) to propagate the target volumes without implanting radio-opaque markers and assess its consequence on the margin that should be used in that context. 
Approach 
An emulator of a CBCT-STAR-dedicated treatment planning system was used to generate plans for 32 liver SABR patients. Three target volume propagation strategies were compared, analysing the volume difference between the GTVPropagated and the GTVConventional, and the vector lengths between their centres of mass (lCoM). These propagation strategies were: (1) structure-guided deformable registration with deformable GTV propagation; (2) rigid registration with rigid GTV propagation; and (3) image-guided deformable registration with rigid GTV propagation. Adaptive margin calculation integrated propagation errors, while interfraction position errors were removed. Scheduled plans (PlanNon-adaptive) and daily-adapted plans (PlanAdaptive) were compared for each treatment fraction.
Main results 
The image-guided deformable registration with rigid GTV propagation was the best propagation strategy ...
Source: Physics in Medicine and Biology - Category: Physics Authors: Source Type: research