Understanding and controlling the effect of lossy raw data compression on CT images.
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| Title: | Understanding and controlling the effect of lossy raw data compression on CT images. |
|---|---|
| Authors: | Wang, Adam S.1 adamwang@stanford.edu, Pelc, Norbert J.2 |
| Source: | Medical Physics. Aug2009, Vol. 36 Issue 8, p3643-3653. 11p. 2 Black and White Photographs, 7 Diagrams, 5 Graphs. |
| Subjects: | Data transmission systems, Medical technology, Human anatomy, Medical physics, Physiological therapeutics |
| Abstract: | The requirements for raw data transmission through a CT scanner slip ring, through the computation system, and for storage of raw CT data can be quite challenging as scanners continue to increase in speed and to collect more data per rotation. Although lossy compression greatly mitigates this problem, users must be cautious about how errors introduced manifest themselves in the reconstructed images. This paper describes two simple yet effective methods for controlling the effect of errors in raw data compression and describe the impact of each stage on the image errors. A CT system simulator (CATSIM, GE Global Research Center, Niskayuna, NY) was used to generate raw CT datasets that simulate different regions of human anatomy. The raw data are digitized by a 20-bit ADC and companded by a log compander. Lossy compression is performed by quantization and is followed by JPEG-LS (lossless), which takes advantage of the correlations between neighboring measurements in the sinogram. Error feedback, a previously proposed method that controls the spatial distribution of reconstructed image errors, and projection filtering, a newly proposed method that takes advantage of the filtered backprojection reconstruction process, are applied independently (and combined) to study their intended impact on the control and behavior of the additional noise due to the compression methods used. The log compander and the projection filtering method considerably reduce image error levels, while error feedback pushes image errors toward the periphery of the field of view. The results for the images are a compression ratio (CR) of 3 that keeps peak compression errors under 1 HU and a CR of 9 that increases image noise by only 1 HU in common CT applications. Lossy compression can substantially reduce raw CT data size at low computational cost. The proposed methods have the flexibility to operate at a wide range of compression ratios and produce predictable, object-independent, and often imperceptible image artifacts. [ABSTRACT FROM AUTHOR] |
| Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Links: – Type: pdflink Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 43407580 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Understanding and controlling the effect of lossy raw data compression on CT images. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Wang%2C+Adam+S%2E%22">Wang, Adam S.</searchLink><relatesTo>1</relatesTo><i> adamwang@stanford.edu</i><br /><searchLink fieldCode="AR" term="%22Pelc%2C+Norbert+J%2E%22">Pelc, Norbert J.</searchLink><relatesTo>2</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Medical+Physics%22">Medical Physics</searchLink>. Aug2009, Vol. 36 Issue 8, p3643-3653. 11p. 2 Black and White Photographs, 7 Diagrams, 5 Graphs. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Data+transmission+systems%22">Data transmission systems</searchLink><br /><searchLink fieldCode="DE" term="%22Medical+technology%22">Medical technology</searchLink><br /><searchLink fieldCode="DE" term="%22Human+anatomy%22">Human anatomy</searchLink><br /><searchLink fieldCode="DE" term="%22Medical+physics%22">Medical physics</searchLink><br /><searchLink fieldCode="DE" term="%22Physiological+therapeutics%22">Physiological therapeutics</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The requirements for raw data transmission through a CT scanner slip ring, through the computation system, and for storage of raw CT data can be quite challenging as scanners continue to increase in speed and to collect more data per rotation. Although lossy compression greatly mitigates this problem, users must be cautious about how errors introduced manifest themselves in the reconstructed images. This paper describes two simple yet effective methods for controlling the effect of errors in raw data compression and describe the impact of each stage on the image errors. A CT system simulator (CATSIM, GE Global Research Center, Niskayuna, NY) was used to generate raw CT datasets that simulate different regions of human anatomy. The raw data are digitized by a 20-bit ADC and companded by a log compander. Lossy compression is performed by quantization and is followed by JPEG-LS (lossless), which takes advantage of the correlations between neighboring measurements in the sinogram. Error feedback, a previously proposed method that controls the spatial distribution of reconstructed image errors, and projection filtering, a newly proposed method that takes advantage of the filtered backprojection reconstruction process, are applied independently (and combined) to study their intended impact on the control and behavior of the additional noise due to the compression methods used. The log compander and the projection filtering method considerably reduce image error levels, while error feedback pushes image errors toward the periphery of the field of view. The results for the images are a compression ratio (CR) of 3 that keeps peak compression errors under 1 HU and a CR of 9 that increases image noise by only 1 HU in common CT applications. Lossy compression can substantially reduce raw CT data size at low computational cost. The proposed methods have the flexibility to operate at a wide range of compression ratios and produce predictable, object-independent, and often imperceptible image artifacts. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1118/1.3158738 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 11 StartPage: 3643 Subjects: – SubjectFull: Data transmission systems Type: general – SubjectFull: Medical technology Type: general – SubjectFull: Human anatomy Type: general – SubjectFull: Medical physics Type: general – SubjectFull: Physiological therapeutics Type: general Titles: – TitleFull: Understanding and controlling the effect of lossy raw data compression on CT images. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Wang, Adam S. – PersonEntity: Name: NameFull: Pelc, Norbert J. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 08 Text: Aug2009 Type: published Y: 2009 Identifiers: – Type: issn-print Value: 00942405 Numbering: – Type: volume Value: 36 – Type: issue Value: 8 Titles: – TitleFull: Medical Physics Type: main |
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