{"doi":"10.1117/1.jbo.25.1.016002","title":"OpenSFDI: an open-source guide for constructing a spatial frequency domain imaging system","abstract":"<bold>Significance</bold>: Spatial frequency domain imaging (SFDI) is a diffuse optical measurement technique that can quantify tissue optical absorption (μ<sub>a</sub>) and reduced scattering (<inline-formula><mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula>) on a pixel-by-pixel basis. Measurements of μ<sub>a</sub> at different wavelengths enable the extraction of molar concentrations of tissue chromophores over a wide field, providing a noncontact and label-free means to assess tissue viability, oxygenation, microarchitecture, and molecular content. We present here openSFDI: an open-source guide for building a low-cost, small-footprint, three-wavelength SFDI system capable of quantifying μ<sub>a</sub> and <inline-formula><mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula> as well as oxyhemoglobin and deoxyhemoglobin concentrations in biological tissue. The companion website provides a complete parts list along with detailed instructions for assembling the openSFDI system. <bold>Aim</bold>: We describe the design of openSFDI and report on the accuracy and precision of optical property extractions for three different systems fabricated according to the instructions on the openSFDI website. <bold>Approach</bold>: Accuracy was assessed by measuring nine tissue-simulating optical phantoms with a physiologically relevant range of μ<sub>a</sub> and <inline-formula><mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula> with the openSFDI systems and a commercial SFDI device. Precision was assessed by repeatedly measuring the same phantom over 1 h. <bold>Results</bold>: The openSFDI systems had an error of 0 ± 6 % in μ<sub>a</sub> and −2 ± 3 % in <inline-formula><mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula>, compared to a commercial SFDI system. Bland–Altman analysis revealed the limits of agreement between the two systems to be ± 0.004 mm<sup> − 1</sup> for μ<sub>a</sub> and −0.06 to 0.1 mm<sup> − 1</sup> for <inline-formula><mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula>. The openSFDI system had low drift with an average standard deviation of 0.0007 mm<sup> − 1</sup> and 0.05 mm<sup> − 1</sup> in μ<sub>a</sub> and <inline-formula><mml:math display=\"inline\" xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"><mml:mrow><mml:msubsup><mml:mrow><mml:mi>μ</mml:mi></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula>, respectively. <bold>Conclusion</bold>: The openSFDI provides a customizable hardware platform for research groups seeking to utilize SFDI for quantitative diffuse optical imaging.","journal":"Journal of Biomedical Optics","year":2020,"id":66536,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":50,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9606,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":352784,"name":"Kavon Karrobi","orcid":"0000-0001-7034-6937","position":1,"is_corresponding":false},{"id":354572,"name":"Joseph P. Angelo","orcid":null,"position":2,"is_corresponding":false},{"id":354573,"name":"Wyatt M. Austin","orcid":null,"position":3,"is_corresponding":false},{"id":307461,"name":"Syeda Tabassum","orcid":"0000-0003-4570-4768","position":4,"is_corresponding":false},{"id":350459,"name":"Enagnon Aguénounon","orcid":"0000-0002-5709-6539","position":5,"is_corresponding":false},{"id":352785,"name":"Karissa Tilbury","orcid":"0000-0003-0841-1077","position":6,"is_corresponding":false},{"id":352786,"name":"Rolf B. Saager","orcid":"0000-0002-3497-1257","position":7,"is_corresponding":false},{"id":350461,"name":"Sylvain Gioux","orcid":"0000-0002-3006-5345","position":8,"is_corresponding":false},{"id":295184,"name":"Darren Roblyer","orcid":"0000-0002-5301-4364","position":9,"is_corresponding":false},{"id":352783,"name":"Matthew B. Applegate","orcid":"0000-0002-1430-1192","position":0,"is_corresponding":true}],"reference_count":49,"raw_metadata":null,"created_at":"2026-07-18T21:14:50.590588Z","pmid":"31925946","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}