Variations in optical coherence tomography resolution and uniformity: a multi-system performance comparison

Anthony Fouad; T Joshua Pfefer; Chao-Wei Chen; Wei Gong; Anant Agrawal; Peter H Tomlins; Peter D Woolliams; Rebekah A Drezek; Yu Chen

doi:10.1364/BOE.5.002066

Variations in optical coherence tomography resolution and uniformity: a multi-system performance comparison

Biomed Opt Express. 2014 Jun 9;5(7):2066-81. doi: 10.1364/BOE.5.002066. eCollection 2014 Jul 1.

Authors

Anthony Fouad¹, T Joshua Pfefer², Chao-Wei Chen¹, Wei Gong³, Anant Agrawal², Peter H Tomlins⁴, Peter D Woolliams⁵, Rebekah A Drezek⁶, Yu Chen⁷

Affiliations

¹ Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA ; Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.
² Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA.
³ Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD, USA ; Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA ; College of Photonic and Electronic Engineering, Fujian Normal University, Fuzhou, Fujian, China.
⁴ Barts and The London School of Medicine and Dentistry, Queen Mary University of London, E1 1BB, London, UK.
⁵ Functional Materials Group, National Physical Laboratory, Teddington, UK.
⁶ Department of Bioengineering, Rice University, Houston, TX, USA.
⁷ Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.

Abstract

Point spread function (PSF) phantoms based on unstructured distributions of sub-resolution particles in a transparent matrix have been demonstrated as a useful tool for evaluating resolution and its spatial variation across image volumes in optical coherence tomography (OCT) systems. Measurements based on PSF phantoms have the potential to become a standard test method for consistent, objective and quantitative inter-comparison of OCT system performance. Towards this end, we have evaluated three PSF phantoms and investigated their ability to compare the performance of four OCT systems. The phantoms are based on 260-nm-diameter gold nanoshells, 400-nm-diameter iron oxide particles and 1.5-micron-diameter silica particles. The OCT systems included spectral-domain and swept source systems in free-beam geometries as well as a time-domain system in both free-beam and fiberoptic probe geometries. Results indicated that iron oxide particles and gold nanoshells were most effective for measuring spatial variations in the magnitude and shape of PSFs across the image volume. The intensity of individual particles was also used to evaluate spatial variations in signal intensity uniformity. Significant system-to-system differences in resolution and signal intensity and their spatial variation were readily quantified. The phantoms proved useful for identification and characterization of irregularities such as astigmatism. Our multi-system results provide evidence of the practical utility of PSF-phantom-based test methods for quantitative inter-comparison of OCT system resolution and signal uniformity.

Keywords: (110.3000) Image quality assessment; (110.4850) Optical transfer functions; (170.4500) Optical coherence tomography; (350.4800) Optical standards and testing.