Inter-Observer Delineation Differences in Esophageal Cancer GTV on MR, CT, and PET/CT Protokol šečerov Ermenc 28dec19

Esophageal cancer radiotherapy requires accurate delineation of the gross tumor volume (GTV) to ensure adequate tumor coverage and to minimize radiation dose to surrounding organs at risk. Computed tomography (CT) is routinely used for target delineation, while positron emission tomography-computed tomography (PET/CT) may provide additional functional information. However, uncertainty in tumor boundaries and inter-observer variation remain clinically relevant issues. Magnetic resonance imaging (MRI) provides improved soft tissue contrast and diffusion-weighted imaging (DWI) information, which may improve visualization of esophageal tumors. This study evaluates whether MRI-based imaging, alone or fused with CT or PET/CT, reduces inter-observer variation in GTV delineation compared with standard CT and PET/CT-based delineation. A total of 21 patients with locally advanced esophageal cancer undergoing standard radiotherapy preparation will undergo MRI simulation in addition to routine CT and PET/CT simulation. Five experienced radiation oncologists will independently delineate the primary tumor GTV on CT, MRI, PET/CT, CT-MRI fusion, and PET/CT-MRI fusion datasets. Inter-observer variation will be assessed using conformity indices and spatial analysis tools.

Sex

All

Minimum age

18 Years

Inclusion Criteria:

* Age ≥18 years
* Locally advanced esophageal cancer (T1b-4b, N0-N+, M0)
* Siewert type I or II for distal esophageal tumors
* Planned preoperative or definitive chemoradiotherapy
* Written informed consent for participation in the study
* No contraindications for MRI

Exclusion Criteria:

* Implanted metallic objects with magnetic properties or electromagnetic devices without MRI compatibility confirmation
* Physical or psychological conditions preventing informed consent