Markerless liver online adaptive stereotactic radiotherapy: feasibility analysisCervantes

Julien Pierrard; Stéphanie Deheneffe; David Dechambre; Edmond Sterpin; Xavier Geets; Geneviève Van Ooteghem

doi:10.1088/1361-6560/ad39a1

Markerless liver online adaptive stereotactic radiotherapy: feasibility analysisCervantes

Phys Med Biol. 2024 Apr 22;69(9). doi: 10.1088/1361-6560/ad39a1.

Authors

Julien Pierrard^{1

2}, Stéphanie Deheneffe³, David Dechambre², Edmond Sterpin^{1

4}, Xavier Geets^{1

2}, Geneviève Van Ooteghem^{1

2}

Affiliations

¹ UCLouvain, Institut de Recherche Experimentale et Clinique (IREC), Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), B-1200 Brussels, Belgium.
² Radiation Oncology Department, Cliniques Universitaires Saint-Luc, B-1200 Brussels, Belgium.
³ Radiation Oncology Department, CHU-UCL-Namur, Site Sainte-Elisabeth, B-5000 Namur, Belgium.
⁴ KU Leuven, Department of Oncology, Laboratory of Experimental Radiotherapy, KU Leuven, Leuven, Belgium.

PMID: 38565128
DOI: 10.1088/1361-6560/ad39a1

Abstract

Objective. Radio-opaque markers are recommended for image-guided radiotherapy in liver stereotactic ablative radiotherapy (SABR), but their implantation is invasive. We evaluate in thisin-silicostudy 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 GTV_Propagatedand the GTV_Conventional, the vector lengths between their centres of mass (l_CoM), and the 95th percentile of the Hausdorff distance between these two volumes (HD95). 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 (Plan_Non-adaptive) and daily-adapted plans (Plan_Adaptive) were compared for each treatment fraction.Main results.The image-guided deformable registration with rigid GTV propagation was the best propagation strategy regarding tol_CoM(mean: 4.3 +/- 2.1 mm), HD95 (mean 4.8 +/- 3.2 mm) and volume preservation between GTV_Propagatedand GTV_Conventional. This resulted in a planning target volume (PTV) margin increase (+69.1% in volume on average). Online adaptation (Plan_Adaptive) reduced the violation rate of the most important dose constraints ('priority 1 constraints', 4.2 versus 0.9%, respectively;p< 0.001) and even improved target volume coverage compared to non-adaptive plans (Plan_Non-adaptive).Significance. Markerless CBCT-STAR for liver tumours is feasible using Image-guided deformable registration with rigid GTV propagation. Despite the cost in terms of PTV volumes, daily adaptation reduces constraints violation and restores target volumes coverage.

Keywords: PTV margin; liver SABR; markerless radiotherapy; minimally invasive radiotherapy; online-adaptive radiotherapy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cone-Beam Computed Tomography*
Feasibility Studies*
Humans
Liver Neoplasms* / diagnostic imaging
Liver Neoplasms* / radiotherapy
Liver* / diagnostic imaging
Liver* / radiation effects
Radiosurgery* / methods
Radiotherapy Planning, Computer-Assisted* / methods
Radiotherapy, Image-Guided* / methods