On handling low-dose CT images in the absence of reliable D - PowerPoint Presentation

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On handling low-dose CT images in the absence of reliable D - PPT Presentation

Laks Raghupathi PhD Veerendra Shetty Siemens Corporate Development Center Bangalore India Healthcare 1 System House Algorithms Research Group Matthias Wolf PhD Siemens Medical ID: 503225

2013 dicom amp dose dicom 2013 dose amp siemens information raghupathi handling reliable absence header seminar march copyright rights

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Slide1

On handling low-dose CT images in the absence of reliable DICOM header information

Laks Raghupathi Ph.D. Veerendra ShettySiemens Corporate Development Center, Bangalore, IndiaHealthcare 1 – System House, Algorithms Research Group Matthias Wolf Ph.D. Siemens Medical Solutions USA, Inc., Malvern, PA, USASYNGO R&D US Innovation

Presenter: Laks Raghupathi

March 2013 DICOM International Conference & Seminar

Handling Low Dose CT

Background Capturing Dosage in DICOM Proposed Approach & Methodology Results & Discussion Author Correspondence

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT imagesin the absence of reliable DICOM header information

2Slide3

Background

CT is important diagnostic imaging modality with millions of procedures performed each year Modern image acquisition technologies are intended to enable dose reduction in CT imaging while maintaining diagnostic information Evolving technology with newer scanners and reconstruction kernels. Low dose CT (LDCT) tend to have higher noise and less sharpness LDCT may affect performance of advanced post-processing algorithms, such as Computer-aided Detection (CAD)

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

Capturing Dosage in DICOM

4 The first step is to know the dosage for each imaging procedure “Exposure”, “XRayTubeCurrent”, “KV” capture input attributes CTDoseIndex field captures overall dosage Non-Type 1 attributes – not mandatory Proposal: Radiation Dose Structured Report (RDSR)

CTDIvol (mGy), DLP (mGy * cm), etc. captures dosage All new devices to encode dose in RDSR [1] Drawbacks: Old scanners may not be updated with RDSRLegacy PACS systems may not read this new SR object

__[1] D. Clunie, Extracting, Managing and Rendering DICOM Radiation Dose Information from Legacy & Contemporary CT Modalities, DICOM Intl. Conf., 2010

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

Proposed Approach

5 Smoothing reduces noise, but in excess removes information Algorithms like Lung CAD* expect sharp kernel Soft kernels may affect performance such as high false positive (FP) rates [2] Need to strike balance between noise and sharpness New Idea: Intelligent pre-processing filter to adjust image quality__

[2] M. Yanagawa et al., Pulmonary nodules: Effect of ASIR technique on performance of a CAD system-comparison of performance between different-dose CT scans Eur. J. Rad., 81(10) 2012

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

* Lung CAD research prototype is not commercially available for sale in the USA or elsewhere and is not related to any product.Slide6

Framework

6Scanner 1ReadingWorkplace

Intelligent Pre-Processing* [3]Post-Processing Applications (e.g., CAD)

Scanner 2

PACS

[3] L. Raghupathi et al., An Intelligent Pre-Processing Framework for Standardizing Medical Images for CAD and Other Post-Processing Applications,

Proc. SPIE Med.

Imag

, 2012

*Research prototype is not commercially available for sale in the USA or elsewhere and is not related to any product.

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

Choosing Filters

Original Filter 1 Filter 2 Filter 3 Filter 4

It is possible to adjust sharpness using the filters.

Key question: Which filter is best for Lung CAD* performance?

* Lung CAD research prototype is not commercially available for sale in the USA or elsewhere and is not related to any product.

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

Methodology

8Signal/Contrast to Noise Ratio dependent on locationUse image metrics for “adaptive” pre-processingEstimate noise (N) around air region (carina landmark)Estimate sharpness (S) in air-body borderIteratively filter till desired Noise to Sharpness ratio (NSR) reached

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

NSR Outputs

9OriginalFilter 1Filter 2

Filter 3Filter 4Filter 5

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

LDCT Details & Ground Truth

34 Siemens IRIS Kernel avg. 90 mAs, 40 solid pulmonary nodules (SPN) in 4-30mm dia. 88 Siemens IRIS Kernel simulated at 50, 100 mAs, 67 SPN in 4-30mm dia.10

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

Results

11Trained on large-scale CT datasetsValidation on low-dose CT images at different levelsImproved performance* (mean FP down 66%, median down 50%)

__* Lung CAD research prototype is not commercially available for sale in the USA or elsewhere and is not related to any product.

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

Discussion

12 Proposed approach normalizes images with different dosage Uses measured attributes independent of acquisition parameters Demonstrated potential for improved CAD performance on LDCT Possible to extend to other post-processing applications Potential to enhance their applicability in clinical workflows Practical alternative till DICOM dosage attributes captured

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information

Acknowledgements

13Marc Rose – Healthcare1, Siemens CT DCDr. Sean Zhou and Ingo Schmuecking – SYNGO R&D US

March 2013 DICOM International Conference & Seminar

CorrespondenceVeerendra Shetty

Veerendra.Shetty@siemens.com Head System Function House – Healthcare1Siemens Technology & Services84, Keonics Electronics City, Bangalore, India14

Thank you for your attention !

March 2013 DICOM International Conference & Seminar

L. Raghupathi et al., On handling low-dose CT images

in the absence of reliable DICOM header information