Influence of reconstruction settings on the performance of adaptive thresholding algorithms for FDG‐PET image segmentation in radiotherapy planning
| Autor: | Eugenio Inglese, L. Vigna, Patrizia Della Monica, Gianfranco Loi, Marco Krengli, Roberta Matheoud, Marco Brambilla |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
FDG‐PET/CT
Urinary Bladder Gaussian blur Normal Distribution Iterative reconstruction target volume definition Imaging phantom FDG-PET/CT radiation treatment planning functional imaging symbols.namesake Fluorodeoxyglucose F18 Expectation–maximization algorithm Image Processing Computer-Assisted Humans Radiation Oncology Physics Radiology Nuclear Medicine and imaging Instrumentation Mathematics Contouring Radiation Models Statistical Phantoms Imaging Radiotherapy Planning Computer-Assisted Image segmentation Thresholding Hodgkin Disease Positron-Emission Tomography symbols Regression Analysis Lymph Nodes Tomography X-Ray Computed Algorithm Smoothing Algorithms |
| Zdroj: | Journal of Applied Clinical Medical Physics |
| ISSN: | 1526-9914 |
| Popis: | The purpose of this study was to analyze the behavior of a contouring algorithm for PET images based on adaptive thresholding depending on lesions size and target‐to‐background (TB) ratio under different conditions of image reconstruction parameters. Based on this analysis, the image reconstruction scheme able to maximize the goodness of fit of the thresholding algorithm has been selected. A phantom study employing spherical targets was designed to determine slice‐specific threshold (TS) levels which produce accurate cross‐sectional areas. A wide range of TB ratio was investigated. Multiple regression methods were used to fit the data and to construct algorithms depending both on target cross‐sectional area and TB ratio, using various reconstruction schemes employing a wide range of iteration number and amount of postfiltering Gaussian smoothing. Analysis of covariance was used to test the influence of iteration number and smoothing on threshold determination. The degree of convergence of ordered‐subset expectation maximization (OSEM) algorithms does not influence TS determination. Among these approaches, the OSEM at two iterations and eight subsets with a 6–8 mm post‐reconstruction Gaussian three‐dimensional filter provided the best fit with a coefficient of determination R2=0.90 for cross‐sectional areas ≤ 133 mm 2 and R2=0.95 for cross‐sectional areas > 133 mm 2 . The amount of post‐reconstruction smoothing has been directly incorporated in the adaptive thresholding algorithms. The feasibility of the method was tested in two patients with lymph node FDG accumulation and in five patients using the bladder to mimic an anatomical structure of large size and uniform uptake, with satisfactory results. Slice‐specific adaptive thresholding algorithms look promising as a reproducible method for delineating PET target volumes with good accuracy. PACS numbers: 87.57.nm, 87.55.D‐, 87.57.uk |
| Databáze: | OpenAIRE |
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