{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,15]],"date-time":"2025-11-15T17:19:41Z","timestamp":1763227181588,"version":"build-2065373602"},"reference-count":44,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2022,10,13]],"date-time":"2022-10-13T00:00:00Z","timestamp":1665619200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Diponegoro University","award":["569-187\/UN7.D2\/PP\/VII\/2022"],"award-info":[{"award-number":["569-187\/UN7.D2\/PP\/VII\/2022"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Algorithms"],"abstract":"<jats:p>A bilateral filter is a non-linear denoising algorithm that can reduce noise while preserving the edges. This study explores the characteristics of a bilateral filter in changing the noise and texture within computed tomography (CT) images in an iterative implementation. We collected images of a homogeneous Neusoft phantom scanned with tube currents of 77, 154, and 231 mAs. The images for each tube current were filtered five times with a configuration of sigma space (\u03c3d) = 2 pixels, sigma intensity (\u03c3r) = noise level, and a kernel of 5 \u00d7 5 pixels. To observe the noise texture in each filter iteration, the noise power spectrum (NPS) was obtained for the five slices of each dataset and averaged to generate a stable curve. The modulation-transfer function (MTF) was also measured from the original and the filtered images. Tests on an anthropomorphic phantom image were carried out to observe their impact on clinical scenarios. Noise measurements and visual observations of edge sharpness were performed on this image. Our results showed that the bilateral filter was effective in suppressing noise at high frequencies, which is confirmed by the sloping NPS curve for different tube currents. The peak frequency was shifted from about 0.2 to about 0.1 mm\u22121 for all tube currents, and the noise magnitude was reduced by more than 50% compared to the original images. The spatial resolution does not change with the number of iterations of the filter, which is confirmed by the constant values of MTF50 and MTF10. The test results on the anthropomorphic phantom image show a similar pattern, with noise reduced by up to 60% and object edges remaining sharp.<\/jats:p>","DOI":"10.3390\/a15100374","type":"journal-article","created":{"date-parts":[[2022,10,13]],"date-time":"2022-10-13T20:55:11Z","timestamp":1665694511000},"page":"374","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Impact of Iterative Bilateral Filtering on the Noise Power Spectrum of Computed Tomography Images"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0156-6797","authenticated-orcid":false,"given":"Choirul","family":"Anam","sequence":"first","affiliation":[{"name":"Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Semarang 50275, Indonesia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4218-6259","authenticated-orcid":false,"given":"Ariij","family":"Naufal","sequence":"additional","affiliation":[{"name":"Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Semarang 50275, Indonesia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7119-9633","authenticated-orcid":false,"given":"Heri","family":"Sutanto","sequence":"additional","affiliation":[{"name":"Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Semarang 50275, Indonesia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7702-6554","authenticated-orcid":false,"given":"Kusworo","family":"Adi","sequence":"additional","affiliation":[{"name":"Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Semarang 50275, Indonesia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3187-3595","authenticated-orcid":false,"given":"Geoff","family":"Dougherty","sequence":"additional","affiliation":[{"name":"Department of Applied Physics and Medical Imaging, California State University Channel Islands, Camarillo, CA 93012, USA"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"499","DOI":"10.1016\/S0140-6736(12)60815-0","article-title":"Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: A retrospective cohort study","volume":"380","author":"Pearce","year":"2012","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"W81","DOI":"10.2214\/AJR.12.9226","article-title":"Radiation risk from CT: Implications for cancer screening","volume":"201","author":"Albert","year":"2013","journal-title":"Am. J. Roentgenol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"554","DOI":"10.1177\/0194599814542588","article-title":"Risk of malignancy associated with head and neck CT in children: A systematic review","volume":"151","author":"Chen","year":"2014","journal-title":"Otolaryngol.\u2013Head Neck Surg."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1051\/radiopro\/2019016","article-title":"The \u201cAs Low As Reasonably Achievable\u201d (ALARA) principle: A brief historical overview and a bibliometric analysis of the most cited publications","volume":"54","author":"Yeung","year":"2019","journal-title":"Radioprotection"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Ning, P., Zhu, S., Shi, D., Guo, Y., and Sun, M. (2014). X-ray dose reduction in abdominal computed tomography using advanced iterative reconstruction algorithms. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0092568"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1002\/acm2.12857","article-title":"Patient size matters: Effect of tube current modulation on size-specific dose estimates (SSDE) and image quality in low-dose lung cancer screening CT","volume":"21","author":"Barreto","year":"2020","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1016\/j.acra.2020.02.016","article-title":"Barriers to CT Dose Optimization: The Challenge of Organizational Change","volume":"28","author":"Whitebird","year":"2021","journal-title":"Acad. Radiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"011908","DOI":"10.1118\/1.4851635","article-title":"Adaptive nonlocal means filtering based on local noise level for CT denoising","volume":"41","author":"Li","year":"2014","journal-title":"Med. Phys."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"623","DOI":"10.31661\/jbpe.v0i0.2002-1072","article-title":"Noise reduction in CT images using a selective mean filter","volume":"10","author":"Anam","year":"2020","journal-title":"J. Biomed. Phys. Eng."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"338","DOI":"10.1120\/jacmp.v14i6.4417","article-title":"Scanner and kVp dependence of measured CT numbers in the ACR CT phantom","volume":"14","author":"Cropp","year":"2013","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1002\/acm2.12798","article-title":"Quantification and homogenization of image noise between two CT scanner models","volume":"21","author":"Einstein","year":"2020","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1007\/s12194-014-0286-x","article-title":"Modulation transfer function measurement of CT images by use of a circular edge method with a logistic curve-fitting technique","volume":"8","author":"Takenaga","year":"2015","journal-title":"Radiol. Phys. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1257","DOI":"10.1080\/00036811.2010.483558","article-title":"Construction of local nonlinear filter without staircase effect in image restoration","volume":"90","author":"Wang","year":"2011","journal-title":"Appl. Anal."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"e14207","DOI":"10.1097\/MD.0000000000014207","article-title":"Wiener filter improves diagnostic accuracy of CAD SPECT images-comparison to angiography and CT angiography","volume":"98","author":"Masoomi","year":"2019","journal-title":"Medicine"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Vasilache, S., Ward, K., Cockrell, C., Ha, J., and Najarian, K. (2009). Unified wavelet and Gaussian filtering for segmentation of CT images; application in segmentation of bone in pelvic CT images. BMC Med. Inform. Decis. Mak., 9.","DOI":"10.1186\/1472-6947-9-S1-S8"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Patil, P.D., and Kumbhar, A.D. (2015, January 8\u201310). Bilateral Filter for Image Denoising. Proceedings of the 2015 International Conference on Green Computing and Internet of Things (ICGCIoT), Greater Noida, India.","DOI":"10.1109\/ICGCIoT.2015.7380477"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2324","DOI":"10.1109\/TIP.2008.2006658","article-title":"Multiresolution bilateral filtering for image denoising","volume":"17","author":"Zhang","year":"2008","journal-title":"IEEE Trans. Image Process."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"664","DOI":"10.1109\/TIP.2008.919949","article-title":"Adaptive bilateral filter for sharpness enhancement and noise removal","volume":"17","author":"Zhang","year":"2008","journal-title":"IEEE Trans. Image Process."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"782","DOI":"10.1016\/j.compeleceng.2018.02.033","article-title":"An image driven bilateral filter with adaptive range and spatial parameters for denoising Magnetic Resonance Images","volume":"6","author":"Joseph","year":"2018","journal-title":"Comput. Electr. Eng."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1521","DOI":"10.1109\/TVCG.2010.264","article-title":"Bilateral Normal Filtering for Mesh Denoising","volume":"17","author":"Zheng","year":"2011","journal-title":"IEEE Trans. Vis. Comput. Graph."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Peng, H., and Rao, R. (2010, January 26\u201329). Bilateral kernel parameter optimization by risk minimization. Proceedings of the IEEE International Conference on Image Processing, Hong Kong, China.","DOI":"10.1109\/ICIP.2010.5651045"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.asoc.2016.02.043","article-title":"Determination of optimal parameters for bilateral filter in brain MR image denoising","volume":"43","author":"Akar","year":"2016","journal-title":"Appl. Soft Comput."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1555","DOI":"10.1109\/LSP.2018.2866949","article-title":"Optimized Fourier Bilateral Filtering","volume":"25","author":"Ghosh","year":"2018","journal-title":"IEEE Signal Process. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"729924","DOI":"10.3389\/fnbot.2022.729924","article-title":"Adaptive Bilateral Texture Filter for Image Smoothing","volume":"16","author":"Xu","year":"2022","journal-title":"Front. Neurorobot."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1751","DOI":"10.1109\/TIP.2010.2095020","article-title":"Lazy Sliding Window Implementation of the Bilateral Filter on Parallel Architectures","volume":"20","author":"Bronstein","year":"2011","journal-title":"IEEE Trans. Image Process."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"346","DOI":"10.1007\/s10851-015-0583-y","article-title":"On a Fast Bilateral Filtering Formulation Using Functional Rearrangements","volume":"53","author":"Galiano","year":"2015","journal-title":"J. Math. Imaging Vis."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1561\/0600000020","article-title":"Bilateral Filtering: Theory and Applications","volume":"4","author":"Paris","year":"2009","journal-title":"Found. Trends Comput. Graph. Vis."},{"key":"ref_28","first-page":"33","article-title":"Iterative Bilateral Filter and Non-Local Mean","volume":"106","author":"Anh","year":"2014","journal-title":"Int. J. Comput. Appl."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1118\/1.4939061","article-title":"Estimating local noise power spectrum from a few FBP-reconstructed CT scans","volume":"43","author":"Zeng","year":"2016","journal-title":"Med. Phys."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"428","DOI":"10.1120\/jacmp.v17i5.6225","article-title":"A noise power spectrum study of a new model-based iterative reconstruction system: Veo 3.0","volume":"17","author":"Li","year":"2016","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1120\/jacmp.v17i3.5841","article-title":"Practical considerations for noise power spectra estimation for clinical CT scanners","volume":"17","author":"Dolly","year":"2016","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"043024","DOI":"10.1117\/1.JEI.23.4.043024","article-title":"Performance of bilateral filtering on Gaussian noise","volume":"23","author":"Park","year":"2014","journal-title":"J. Electron. Imag."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"6048","DOI":"10.1118\/1.4752209","article-title":"Quantitative comparison of noise texture across CT scanners from different manufacturers","volume":"39","author":"Solomon","year":"2012","journal-title":"Med. Phys."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"e735","DOI":"10.1002\/mp.13763","article-title":"Performance evaluation of computed tomography systems: Summary of AAPM Task Group 233","volume":"46","author":"Samei","year":"2019","journal-title":"Med. Phys."},{"key":"ref_35","unstructured":"(2022, July 10). ImQuest. Available online: https:\/\/deckard.duhs.duke.edu\/~samei\/tg233.html."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"012001","DOI":"10.1088\/1742-6596\/1248\/1\/012001","article-title":"Validation of the tail replacement method in MTF calculations using the homogeneous and non-homogeneous edges of a phantom","volume":"1248","author":"Anam","year":"2019","journal-title":"J. Phys. Conf. Ser."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"e13719","DOI":"10.1002\/acm2.13719","article-title":"Automated development of the contrast-detail curve based on statistical low-contrast detectability in CT images","volume":"9","author":"Anam","year":"2022","journal-title":"J. Appl. Clin. Med. Phys."},{"key":"ref_38","first-page":"163","article-title":"An improved method of automated noise measurement system in CT images","volume":"11","author":"Anam","year":"2021","journal-title":"J. Biomed. Phys. Eng."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"3857","DOI":"10.1088\/0031-9155\/56\/13\/008","article-title":"TIPS bilateral noise reduction in 4D CT perfusion scans produces high-quality cerebral blood flow maps","volume":"56","author":"Mendrik","year":"2011","journal-title":"Phys. Med. Biol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1499","DOI":"10.1109\/TIP.2006.871137","article-title":"The staircasing effect in neighborhood filters and its solution","volume":"15","author":"Buades","year":"2006","journal-title":"IEEE Trans. Image Process."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"385","DOI":"10.1007\/s12194-013-0212-7","article-title":"Assessment of bilateral filter on 1\/2-dose chest-pelvis CT views","volume":"6","author":"Daear","year":"2013","journal-title":"Radiol. Phys. Technol."},{"key":"ref_42","unstructured":"Buades, A., Coll, B., and Morel, J.M. (2005, January 20\u201325). A non-local algorithm for image denoising. Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR\u201905), San Diego, CA, USA."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1016\/j.ejrad.2018.10.025","article-title":"Basics of iterative reconstruction methods in computed tomography: A vendor-independent overview","volume":"109","author":"Stiller","year":"2018","journal-title":"Eur. J. Radiol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1016\/j.crad.2021.01.010","article-title":"The future of CT: Deep learning reconstruction","volume":"76","author":"McLeavy","year":"2021","journal-title":"Clin. Radiol."}],"container-title":["Algorithms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1999-4893\/15\/10\/374\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T00:53:14Z","timestamp":1760143994000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1999-4893\/15\/10\/374"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,10,13]]},"references-count":44,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2022,10]]}},"alternative-id":["a15100374"],"URL":"https:\/\/doi.org\/10.3390\/a15100374","relation":{},"ISSN":["1999-4893"],"issn-type":[{"type":"electronic","value":"1999-4893"}],"subject":[],"published":{"date-parts":[[2022,10,13]]}}}