{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T10:40:39Z","timestamp":1783420839082,"version":"3.54.6"},"reference-count":44,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2025,11,30]],"date-time":"2025-11-30T00:00:00Z","timestamp":1764460800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Erciyes University Scientific Research Projects Coordination Unit","award":["FBA-2023-12864"],"award-info":[{"award-number":["FBA-2023-12864"]}]},{"name":"Erciyes University Scientific Research Projects Coordination Unit","award":["FAPD-2025-15180"],"award-info":[{"award-number":["FAPD-2025-15180"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Additive manufacturing (AM) has rapidly evolved due to its design flexibility, ability to enable personalized fabrication, and reduced material waste. In the medical field, fused filament fabrication (FFF) facilitates the production of individualized anatomical models for surgical preparation, education, medical imaging, and calibration. However, the lack of filaments with X-ray attenuation similar to that of biological hard tissues limits their use in radiological imaging. To address this limitation, a radiopaque filament was developed by incorporating gadolinium oxide (Gd2O3) into a biodegradable poly(lactic acid) (PLA) matrix at 1, 3, and 5 wt.%. Thermal and rheological properties were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and melt flow index (MFI) analyses, revealing minor variations that did not affect printability under standard FFF conditions (200 \u00b0C nozzle, 60 \u00b0C build plate, 0.12 mm layer height). Microstructural analysis via field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, and micro-computed tomography (micro-CT) confirmed homogeneous Gd2O3 dispersion without nozzle blockage. Radiopacity was evaluated using gyroid infill cubes, and increasing Gd2O3 content enhanced X-ray attenuation, with 3 wt.% Gd2O3 reaching Hounsfield Unit (HU) values comparable to cortical bone. Finally, the L1 vertebra phantom fabricated from the 3 wt.% Gd2O3 filament exhibited mean HU values of approximately +200 to +250 HU at 50% infill density (trabecular bone region) and around +1000 HU at 100% infill density (cortical bone region), demonstrating the filament\u2019s potential for producing cost-effective, radiopaque, and biodegradable phantoms for computed tomography (CT) imaging.<\/jats:p>","DOI":"10.3390\/polym17233193","type":"journal-article","created":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T15:31:46Z","timestamp":1764689506000},"page":"3193","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Development and Characterization of a Biodegradable Radiopaque PLA\/Gd2O3 Filament for Bone-Equivalent Phantom Produced via Fused Filament Fabrication"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9746-3500","authenticated-orcid":false,"given":"\u00d6zkan","family":"\u00d6zmen","sequence":"first","affiliation":[{"name":"Department of Industrial Design Engineering, Faculty of Engineering, Erciyes University, 38039 Kayseri, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-8600-5138","authenticated-orcid":false,"given":"Sena","family":"Dursun","sequence":"additional","affiliation":[{"name":"Graduate School of Natural and Applied Sciences, Department of Industrial Design Engineering, Erciyes University, 38039 Kayseri, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1533033819870208","DOI":"10.1177\/1533033819870208","article-title":"A Systematic Review on 3D-Printed Imaging and Dosimetry Phantoms in Radiation Therapy","volume":"18","author":"Tino","year":"2019","journal-title":"Technol. Cancer Res. Treat."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1140","DOI":"10.1016\/j.procir.2023.03.154","article-title":"Classification of Phantoms for Medical Imaging","volume":"119","author":"Wegner","year":"2023","journal-title":"Procedia CIRP"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4537","DOI":"10.1007\/s12206-024-2407-8","article-title":"3D Printed Phantoms for Medical Imaging: Recent Developments and Challenges","volume":"38","author":"Wegner","year":"2024","journal-title":"J. Mech. Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Polo, S., Garc\u00eda-Dom\u00ednguez, A., Rubio, E.M., and Claver, J. (2025). Lattice Structures in Additive Manufacturing for Biomedical Applications: A Systematic Review. Polymers, 17.","DOI":"10.3390\/polym17172285"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Sun, Z., Wong, Y.H., and Yeong, C.H. (2023). Patient-Specific 3D-Printed Low-Cost Models in Medical Education and Clinical Practice. Micromachines, 14.","DOI":"10.3390\/mi14020464"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"106","DOI":"10.1016\/j.radphyschem.2017.02.009","article-title":"Evaluation of 3D Printing Materials for Fabrication of a Novel Multi-Functional 3D Thyroid Phantom for Medical Dosimetry and Image Quality","volume":"135","author":"Alssabbagh","year":"2017","journal-title":"Radiat. Phys. Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"106","DOI":"10.14316\/pmp.2017.28.3.106","article-title":"Feasibility Of Fabricating Variable Density Phantoms Using 3D Printing For Quality Assurance (QA) In Radiotherapy","volume":"28","author":"Oh","year":"2017","journal-title":"Prog. Med. Phys."},{"key":"ref_8","first-page":"011003","article-title":"Assessment of 11 Available Materials with Custom Three-Dimensional-Printing Patterns for the Simulation of Muscle, Fat, and Lung Hounsfield Units in Patient-Specific Phantoms","volume":"1","author":"Okkalidis","year":"2018","journal-title":"J. Eng. Sci. Med. Diagn. Ther."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4600","DOI":"10.1002\/mp.13154","article-title":"A Novel 3D Printing Method for Accurate Anatomy Replication in Patient-Specific Phantoms","volume":"45","author":"Okkalidis","year":"2018","journal-title":"Med. Phys."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Okkalidis, N., and Bliznakova, K. (2022). A Voxel-by-Voxel Method for Mixing Two Filaments during a 3D Printing Process for Soft-Tissue Replication in an Anthropomorphic Breast Phantom. Phys. Med. Biol., 67.","DOI":"10.1088\/1361-6560\/aca640"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"105061","DOI":"10.1016\/j.ejmp.2025.105061","article-title":"Assessment of Physical Phantoms Produced in the PHENOMENO Project Utilizing Three Fused Filament Fabrication Approaches","volume":"136","author":"Bliznakova","year":"2025","journal-title":"Phys. Medica"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Ahmed, A.M.M., Buschmann, M., Breyer, L., Kuntner, C., and Homolka, P. (2024). Tailoring the Mass Density of 3D Printing Materials for Accurate X-Ray Imaging Simulation by Controlled Underfilling for Radiographic Phantoms. Polymers, 16.","DOI":"10.3390\/polym16081116"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1016\/j.compscitech.2017.10.023","article-title":"X-Ray Computed Tomography of Polymer Composites","volume":"156","author":"Garcea","year":"2018","journal-title":"Compos. Sci. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"108906","DOI":"10.1016\/j.radphyschem.2020.108906","article-title":"Commercial Filament Testing for Use in 3D Printed Phantoms","volume":"174","author":"Savi","year":"2020","journal-title":"Radiat. Phys. Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1174","DOI":"10.1007\/s40042-022-00593-w","article-title":"Study on the Radiological Characteristics of Metal Infilled Filaments for Three-Dimensional Printing according to the Infill Rate and Pattern","volume":"81","author":"Kim","year":"2022","journal-title":"J. Korean Phys. Soc."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"111","DOI":"10.1016\/j.ejmp.2017.05.051","article-title":"Radiological Properties of 3D Printed Materials in Kilovoltage and Megavoltage Photon Beams","volume":"38","author":"Dancewicz","year":"2017","journal-title":"Phys. Medica"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1002\/acm2.13064","article-title":"Fabrication of a Pediatric Torso Phantom with Multiple Tissues Represented Using a Dual Nozzle Thermoplastic 3D Printer","volume":"21","author":"Mille","year":"2020","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"109439","DOI":"10.1016\/j.matdes.2020.109439","article-title":"The Interlace Deposition Method of Bone Equivalent Material Extrusion 3D Printing for Imaging in Radiotherapy","volume":"199","author":"Tino","year":"2021","journal-title":"Mater. Des."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"701","DOI":"10.1007\/s13246-020-00864-5","article-title":"Quasi-Simultaneous 3D Printing of Muscle-, Lung-, and Bone-Equivalent Media: A Proof-of-Concept Study","volume":"43","author":"Kairn","year":"2020","journal-title":"Phys. Eng. Sci. Med."},{"key":"ref_20","first-page":"10","article-title":"Impact of Infill Percentages in Visual Homogeneity for 3D Printed Imaging Phantoms","volume":"8","author":"Andrade","year":"2020","journal-title":"Braz. J. Radiat. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2206","DOI":"10.1002\/mp.14100","article-title":"Accurate Replication of Soft and Bone Tissues with 3D Printing","volume":"47","author":"Okkalidis","year":"2020","journal-title":"Med. Phys."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1016\/j.ejmp.2022.09.009","article-title":"A Filament 3D Printing Approach for CT-Compatible Bone Tissues Replication","volume":"102","author":"Okkalidis","year":"2022","journal-title":"Phys. Medica"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"100080","DOI":"10.1016\/j.stlm.2022.100080","article-title":"A Radiographic Analysis of Common 3D Print Materials and Assessment of Their Fidelity within Vertebral Models","volume":"8","author":"Pullen","year":"2022","journal-title":"Ann. 3D Print. Med."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"4734","DOI":"10.1002\/mp.16587","article-title":"Reproduction of a Conventional Anthropomorphic Female Chest Phantom by 3D Printing: Comparison of Image Contrasts and Absorbed Doses in CT","volume":"50","author":"Kunert","year":"2023","journal-title":"Med. Phys."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"113719","DOI":"10.1016\/j.matdes.2025.113719","article-title":"Design and Additive Manufacture of Patient-Specific Head Phantom for Radiotherapy","volume":"252","author":"Lin","year":"2025","journal-title":"Mater. Des."},{"key":"ref_26","first-page":"102695","article-title":"Fused Filament Fabrication of Complex Anatomical Phantoms with Infill-Tunable Image Contrast","volume":"52","author":"Darling","year":"2022","journal-title":"Addit. Manuf."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Savi, M., Andrade, M.A.B., Villani, D., Rodrigues, O., and Potiens, M.P.A. (2022). Development of Radiopaque FFF Filaments for Bone and Teeth Representation in 3D Printed Radiological Objects. Braz. J. Radiat. Sci., 10.","DOI":"10.15392\/bjrs.v10i1.1739"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"6720","DOI":"10.1002\/pc.28229","article-title":"Acrylonitrile-Butadiene-Styrene-Based Composites for the Manufacture of Anthropomorphic Simulators","volume":"45","author":"Thomazi","year":"2024","journal-title":"Polym. Compos."},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Okkalidis, F., Chatzigeorgiou, C., Okkalidis, N., Dukov, N., Milev, M., Bliznakov, Z., Mettivier, G., Russo, P., and Bliznakova, K. (2024). Characterization of Commercial and Custom-Made Printing Filament Materials for Computed Tomography Imaging of Radiological Phantoms. Technologies, 12.","DOI":"10.3390\/technologies12080139"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"789","DOI":"10.1002\/jbm.b.34744","article-title":"3D Printed Bismuth Oxide\u2013Polylactic Acid Composites for Radio-Mimetic Computed Tomography Spine Phantoms","volume":"109","author":"Arnold","year":"2021","journal-title":"J. Biomed. Mater. Res. Part B Appl. Biomater."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Choi, Y., Jang, Y.J., Kim, K.B., Bahng, J., and Choi, S.H. (2022). Characterization of Tissue Equivalent Materials Using 3D Printing for Patient-Specific DQA in Radiation Therapy. Appl. Sci., 12.","DOI":"10.3390\/app12199768"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"5289","DOI":"10.1007\/s00170-023-12206-2","article-title":"PLA-Based Ceramic Composites for 3D Printing of Anthropomorphic Simulators","volume":"128","author":"Thomazi","year":"2023","journal-title":"Int. J. Adv. Manuf. Technol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"465","DOI":"10.1108\/RPJ-06-2024-0244","article-title":"Novel Radiopaque Poly(Lactic Acid) Filament Production for Phantom Applications, and Model Studies for Hard Tissues","volume":"31","author":"Yasan","year":"2025","journal-title":"Rapid Prototyp. J."},{"key":"ref_34","unstructured":"Berger, M.J., Hubbell, J.H., Seltzer, S.M., Chang, J., Coursey, J.S., Sukumar, R., Zucker, D.S., and Olsen, K. (2025, September 01). XCOM: Photon Cross Section Database (Version 1.5), Available online: http:\/\/physics.nist.gov\/xcom."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Poltabtim, W., Thumwong, A., Wimolmala, E., Rattanapongs, C., Tokonami, S., Ishikawa, T., and Saenboonruang, K. (2022). Dual X-Ray- and Neutron-Shielding Properties of Gd2O3\/NR Composites with Autonomous Self-Healing Capabilities. Polymers, 14.","DOI":"10.3390\/polym14214481"},{"key":"ref_36","unstructured":"Hsieh, J. (2003). Computed Tomography: Principles, Design, Artifacts, and Recent Advances, SPIE Press."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"112103","DOI":"10.1016\/j.radphyschem.2024.112103","article-title":"Computed Tomography Imaging Analysis of a Fused Filament Fabrication (FFF) 3D Printed Neck\u2013Thyroid Phantom for Multidisciplinary Purposes","volume":"224","author":"Villani","year":"2024","journal-title":"Radiat. Phys. Chem."},{"key":"ref_38","unstructured":"Comet Technologies Canada Inc. (2025, September 01). Dragonfly 2022.2 [Windows]. Available online: http:\/\/www.theobjects.com\/dragonfly."},{"key":"ref_39","unstructured":"(2025, September 01). UltiMaker Cura 5.10.0, Available online: https:\/\/ultimaker.com\/software\/ultimaker-cura\/."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1045","DOI":"10.1007\/s10278-013-9622-7","article-title":"The Cancer Imaging Archive (TCIA): Maintaining and Operating a Public Information Repository","volume":"26","author":"Clark","year":"2013","journal-title":"J. Digit. Imaging"},{"key":"ref_41","unstructured":"Akin, O., Elnajjar, P., Heller, M., Jarosz, R., Erickson, B.J., Kirk, S., Lee, Y., Linehan, M.W., Gautam, R., and Vikram, R. (2025, November 19). The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma Collection (TCGA-KIRC) (Version 3) [Data Set]; The Cancer Imaging Archive. Available online: https:\/\/www.cancerimagingarchive.net\/collection\/tcga-kirc\/."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1323","DOI":"10.1016\/j.mri.2012.05.001","article-title":"3D Slicer as an Image Computing Platform for the Quantitative Imaging Network","volume":"30","author":"Fedorov","year":"2012","journal-title":"Magn. Reson. Imaging"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"101745","DOI":"10.1039\/C5RA19303F","article-title":"Enhanced Thermal Decomposition Kinetics of Poly(Lactic Acid) Sacrificial Polymer Catalyzed by Metal Oxide Nanoparticles","volume":"5","author":"Liu","year":"2015","journal-title":"RSC Adv."},{"key":"ref_44","doi-asserted-by":"crossref","unstructured":"Tino, R., Leary, M., Yeo, A., Brandt, M., and Kron, T. (2019). Gyroid Structures for 3D-Printed Heterogeneous Radiotherapy Phantoms. Phys. Med. Biol., 64.","DOI":"10.1088\/1361-6560\/ab48ab"}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/23\/3193\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T15:38:26Z","timestamp":1764689906000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/23\/3193"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,11,30]]},"references-count":44,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2025,12]]}},"alternative-id":["polym17233193"],"URL":"https:\/\/doi.org\/10.3390\/polym17233193","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,11,30]]}}}