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Technol Cancer Res Treat. 2018 Jan 1;17:1533034617749419. doi: 10.1177/1533034617749419.

Line-Enhanced Deformable Registration of Pulmonary Computed Tomography Images Before and After Radiation Therapy With Radiation-Induced Fibrosis.

Author information

1
1 Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, USA.
2
2 Department of Radiology, Florida Hospital, Orlando, FL, USA.

Abstract

PURPOSE:

The deformable registration of pulmonary computed tomography images before and after radiation therapy is challenging due to anatomic changes from radiation fibrosis. We hypothesize that a line-enhanced registration algorithm can reduce landmark error over the entire lung, including the irradiated regions, when compared to an intensity-based deformable registration algorithm.

MATERIALS:

Two intensity-based B-spline deformable registration algorithms of pre-radiation therapy and post-radiation therapy images were compared. The first was a control intensity-based algorithm that utilized computed tomography images without modification. The second was a line enhancement algorithm that incorporated a Hessian-based line enhancement filter prior to deformable image registration. Registrations were evaluated based on the landmark error between user-identified landmark pairs and the overlap ratio.

RESULTS:

Twenty-one patients with pre-radiation therapy and post-radiation therapy scans were included. The median time interval between scans was 1.2 years (range: 0.3-3.3 years). Median landmark errors for the line enhancement algorithm were significantly lower than those for the control algorithm over the entire lung (1.67 vs 1.83 mm; P < .01), as well as within the 0 to 5 Gy (1.40 vs 1.57; P < .01) and >5 Gy (2.25 vs 3.31; P < .01) dose intervals. The median lung mask overlap ratio for the line enhancement algorithm (96.2%) was greater than that for the control algorithm (95.8%; P < .01). Landmark error within the >5 Gy dose interval demonstrated a significant inverse relationship with post-radiation therapy fibrosis enhancement after line enhancement filtration (Pearson correlation coefficient = -0.48; P = .03).

CONCLUSION:

The line enhancement registration algorithm is a promising method for registering images before and after radiation therapy.

KEYWORDS:

deformable registration; line enhancement; lung; radiation therapy

PMID:
29343206
PMCID:
PMC5784562
DOI:
10.1177/1533034617749419
[Indexed for MEDLINE]
Free PMC Article

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