From Lines to Shapes: Geometric-Constrained Segmentation of X-Ray Collimators via Hough Transform

Fuente: arXiv
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Autori principali: El-Zein, Benjamin, Eckert, Dominik, Fieselmann, Andreas, Syben, Christopher, Ritschl, Ludwig, Kappler, Steffen, Stober, Sebastian
Natura: Preprint
Pubblicazione: 2025
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author El-Zein, Benjamin
Eckert, Dominik
Fieselmann, Andreas
Syben, Christopher
Ritschl, Ludwig
Kappler, Steffen
Stober, Sebastian
author_facet El-Zein, Benjamin
Eckert, Dominik
Fieselmann, Andreas
Syben, Christopher
Ritschl, Ludwig
Kappler, Steffen
Stober, Sebastian
contents Collimation in X-ray imaging restricts exposure to the region-of-interest (ROI) and minimizes the radiation dose applied to the patient. The detection of collimator shadows is an essential image-based preprocessing step in digital radiography posing a challenge when edges get obscured by scattered X-ray radiation. Regardless, the prior knowledge that collimation forms polygonal-shaped shadows is evident. For this reason, we introduce a deep learning-based segmentation that is inherently constrained to its geometry. We achieve this by incorporating a differentiable Hough transform-based network to detect the collimation borders and enhance its capability to extract the information about the ROI center. During inference, we combine the information of both tasks to enable the generation of refined, line-constrained segmentation masks. We demonstrate robust reconstruction of collimated regions achieving median Hausdorff distances of 4.3-5.0mm on diverse test sets of real Xray images. While this application involves at most four shadow borders, our method is not fundamentally limited by a specific number of edges.
format Preprint
id arxiv_https___arxiv_org_abs_2509_04437
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle From Lines to Shapes: Geometric-Constrained Segmentation of X-Ray Collimators via Hough Transform
El-Zein, Benjamin
Eckert, Dominik
Fieselmann, Andreas
Syben, Christopher
Ritschl, Ludwig
Kappler, Steffen
Stober, Sebastian
Computer Vision and Pattern Recognition
Medical Physics
Collimation in X-ray imaging restricts exposure to the region-of-interest (ROI) and minimizes the radiation dose applied to the patient. The detection of collimator shadows is an essential image-based preprocessing step in digital radiography posing a challenge when edges get obscured by scattered X-ray radiation. Regardless, the prior knowledge that collimation forms polygonal-shaped shadows is evident. For this reason, we introduce a deep learning-based segmentation that is inherently constrained to its geometry. We achieve this by incorporating a differentiable Hough transform-based network to detect the collimation borders and enhance its capability to extract the information about the ROI center. During inference, we combine the information of both tasks to enable the generation of refined, line-constrained segmentation masks. We demonstrate robust reconstruction of collimated regions achieving median Hausdorff distances of 4.3-5.0mm on diverse test sets of real Xray images. While this application involves at most four shadow borders, our method is not fundamentally limited by a specific number of edges.
title From Lines to Shapes: Geometric-Constrained Segmentation of X-Ray Collimators via Hough Transform
topic Computer Vision and Pattern Recognition
Medical Physics
url https://arxiv.org/abs/2509.04437