Marker-based quantification of interfractional tumor position variation and the use of markers for setup verification in radiation therapy for esophageal cancer.
Radiother Oncol
; 117(3): 412-8, 2015 Dec.
Article
in En
| MEDLINE
| ID: mdl-26475250
ABSTRACT
PURPOSE:
The aim of this study was to quantify interfractional esophageal tumor position variation using markers and investigate the use of markers for setup verification. MATERIALS ANDMETHODS:
Sixty-five markers placed in the tumor volumes of 24 esophageal cancer patients were identified in computed tomography (CT) and follow-up cone-beam CT. For each patient we calculated pairwise distances between markers over time to evaluate geometric tumor volume variation. We then quantified marker displacements relative to bony anatomy and estimated the variation of systematic (Σ) and random errors (σ). During bony anatomy-based setup verification, we visually inspected whether the markers were inside the planning target volume (PTV) and attempted marker-based registration.RESULTS:
Minor time trends with substantial fluctuations in pairwise distances implied tissue deformation. Overall, Σ(σ) in the left-right/cranial-caudal/anterior-posterior direction was 2.9(2.4)/4.1(2.4)/2.2(1.8) mm; for the proximal stomach, it was 5.4(4.3)/4.9(3.2)/1.9(2.4) mm. After bony anatomy-based setup correction, all markers were inside the PTV. However, due to large tissue deformation, marker-based registration was not feasible.CONCLUSIONS:
Generally, the interfractional position variation of esophageal tumors is more pronounced in the cranial-caudal direction and in the proximal stomach. Currently, marker-based setup verification is not feasible for clinical routine use, but markers can facilitate the setup verification by inspecting whether the PTV covers the tumor volume adequately.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Esophageal Neoplasms
/
Chemoradiotherapy
Type of study:
Observational_studies
Limits:
Aged
/
Aged80
/
Female
/
Humans
/
Male
/
Middle aged
Language:
En
Journal:
Radiother Oncol
Year:
2015
Document type:
Article