Can CT Image Truncation Cause False Dose Alerts

first_img Figure 2: Example calculation from truncated images. A message indicates that Water Equivalent Diameter (WED) and Size Specific Dose Estimates (SSDE) should be evaluated with care, as the calculation may not be accurate (screenshot from DOSE, Qaelum).One of the main benefits of a radiation dose management system is the possibility to automatically generate alerts when the dose exceeds certain thresholds. These dose thresholds are mainly based on national Diagnostic Reference Levels (DRLs), which are defined for a standard-sized patient. An advanced dose management system offers the possibility to automatically select the group of patients by defining a patient size range in terms of weight, effective diameter or Water Equivalent Diameter (WED). As weight is not always filled in, WED, an attenuation-based metric, has become the favourite parameter to indicate patient size. But how accurately is WED calculated? Are we sure that our group of standard-sized patients does not include patients with wrong size calculation? Especially when everything happens automatically, how can we know that a high dose alert does not indicate a bigger patient for whom the size was not correctly calculated?Automatic calculation of WED by a dose management system can be performed from the computed tomography (CT) localizer image or the reconstructed axial images. The difficulty in using the localizer lies mainly in the different calibration of pixel values in terms of water attenuation between vendors/scanner models/software versions, the inclusion of table attenuation, the use of edge-enhancement filters, and the wrong positioning that can magnify or minify the patient’s image. The reconstructed axial CT image is presented as an accurate way to measure the WED of the patient on the condition that the full patient tissue is included in the image.1,2But what happens if the axial image is truncated? Can it still be used to estimate the WED?Our research team performed a study to investigate the effect of image truncation on the calculation of water equivalent diameter for chest and abdomen CT scans. We used a set of CT examinations (286 thorax and 222 abdomen CTs) for which the middle slice was not truncated, and then we intentionally truncated the images up to 50 percent (Figure 1). Non-truncated WED values were compared to truncated values.The results indicated that for truncation percentages below 20 percent, the underestimation of the WED was rather small and no correction was needed. For larger truncation percentages, the difference between the non-truncated and truncated WED became larger, and correction factors3 could improve the calculation of WED. The results were presented at the European Congress of Medical Physics (ECMP 2018)4.The study was then broadened to evaluate the effect of truncation on the Size Specific Dose Estimates (SSDE) calculation (Figure 2). The results will be presented at the 2019 American Association of Physicists in Medicine (AAPM) annual meeting.Although defining the Diagnostic Reference Levels for a specific patient size range allows the exclusion of overweight and obese patients, the truncation of the image could lead to a bigger patient being falsely identified as “standard-sized” and generate a dose alert. Knowing the effects of truncation on the calculation can assist in excluding dose alerts from the daily workload.For more information: www.qaelum.comReferences AAPM Report No 204. Size-Specific Dose Estimates (SSDE) in pediatric and adult body CT examinations. Report of AAPM Task Group 204. American Association of Physicists in Medicine, 2011. The CT scanner might not come with protocols that are adequate for each hospital situation, so at Phoenix Children’s Hospital they designed their own protocols, said Dianna Bardo, M.D., director of body MR and co-director of the 3D Innovation Lab at Phoenix Children’s. Video Player is loading.Pierre Qian explains radiotherapy to ablate VTPlay VideoPlayMuteCurrent Time 0:00/Duration 7:34Loaded: 2.19%Stream Type LIVESeek to live, currently playing liveLIVERemaining Time -7:34 Playback Rate1xChaptersChaptersDescriptionsdescriptions off, selectedCaptionscaptions settings, opens captions settings dialogcaptions off, selectedAudio Trackdefault, selectedFullscreenThis is a modal window.Beginning of dialog window. Escape will cancel and close the window.TextColorWhiteBlackRedGreenBlueYellowMagentaCyanTransparencyOpaqueSemi-TransparentBackgroundColorBlackWhiteRedGreenBlueYellowMagentaCyanTransparencyOpaqueSemi-TransparentTransparentWindowColorBlackWhiteRedGreenBlueYellowMagentaCyanTransparencyTransparentSemi-TransparentOpaqueFont Size50%75%100%125%150%175%200%300%400%Text Edge StyleNoneRaisedDepressedUniformDropshadowFont FamilyProportional Sans-SerifMonospace Sans-SerifProportional SerifMonospace SerifCasualScriptSmall CapsReset restore all settings to the default valuesDoneClose Modal DialogEnd of dialog window.Close Modal DialogThis is a modal window. This modal can be closed by pressing the Escape key or activating the close button. Figure 1: Example of an intentionally truncated CT image. The truncation percentage was calculated as the ratio of the patient border touching the field of view to the total patient border (red/(read+blue)). Image courtesy of Qaelum. Dedulle et al. Influence of image truncation on the calculation of Water Equivalent Diameter in Computed Tomography examinations. European Congress of Medical Physics, ECMP 2018, 23 – 25 August 2018, Copenhagen, Denmark. News | Proton Therapy | August 06, 2019 IBA Signs Contract to Install Proton Therapy Center in Kansas IBA (Ion Beam Applications S.A.) recently signed a contract and received the first payment for a Proteus One solution… read more PreviousNext News | Artificial Intelligence | August 05, 2019 Montefiore Nyack Hospital Uses Aidoc AI to Spot Urgent Conditions Faster Montefiore Nyack Hospital, an acute care hospital in Rockland County, N.Y., announced it is utilizing artificial… read more Anam et al. The Size-Specific Dose Estimate (SSDE) for truncated computed tomography images. Radiation Protection Dosimetry, 175, 313-320, 2017. Figure 2: Example calculation from truncated images. A message indicates that Water Equivalent Diameter (WED) and Size Specific Dose Estimates (SSDE) should be evaluated with care, as the calculation may not be accurate (screenshot from DOSE, Qaelum). Related Content Sponsored Content | Case Study | Radiation Dose Management | August 13, 2019 The Challenge of Pediatric Radiation Dose Management Radiation dose management is central to child patient safety. Medical imaging plays an increasing role in the accurate… read more Video Player is loading.Mark Ibrahim explains what EPs need from CT imagingPlay VideoPlayMuteCurrent Time 0:00/Duration 5:23Loaded: 3.08%Stream Type LIVESeek to live, currently playing liveLIVERemaining Time -5:23 Playback Rate1xChaptersChaptersDescriptionsdescriptions off, selectedCaptionscaptions settings, opens captions settings dialogcaptions off, selectedAudio Trackdefault, selectedFullscreenThis is a modal window.Beginning of dialog window. 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Videos | CT Angiography (CTA) | August 07, 2019 VIDEO: Walk Around of a Siemens Go.Top Dedicated Cardiac Scanner This is a quick walk around of the new Siemens Somatom Go.top cardiovascular edition compact computed tomography (CT) read more center_img Video Player is loading.GE Cardiographe cardiac CT scanner at SCCT19Play VideoPlayMuteCurrent Time 0:00/Duration 0:38Loaded: 26.15%Stream Type LIVESeek to live, currently playing liveLIVERemaining Time -0:38 Playback Rate1xChaptersChaptersDescriptionsdescriptions off, selectedCaptionscaptions settings, opens captions settings dialogcaptions off, selectedAudio Trackdefault, selectedFullscreenThis is a modal window.Beginning of dialog window. 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Feature | August 05, 2019 | Dave Fornell, Editor Most Popular Radiology and Radiotherapy Topics in July 2019 August 5, 2019 — Here is the list of the most popular content on the Imaging Technology New (ITN) magazine website fr read more Author’s Note: Niki Fitousi, Ph.D., is head of research at Qaelum. An Dedulle is a Ph.D. researcher for Qaelum. FacebookTwitterLinkedInPrint分享 News | CT Angiography (CTA) | August 06, 2019 Artificial Intelligence Improves Heart Attack Risk Assessment When used with a common heart scan, machine learning, a type of artificial intelligence (AI), does better than… read more Videos | Radiation Therapy | July 30, 2019 VIDEO: Use of Radiotherapy to Noninvasively Ablate Ventricular Tachycardia Pierre Qian, MBBS, read more Videos | CT Angiography (CTA) | August 07, 2019 VIDEO: Walk Around of a GE Cardiographe Dedicated Cardiac CT Scanner This is a quick walk around of the GE Healthcare Cardiographe dedicated cardiac CT system on display at the… read more Videos | Cardiac Imaging | July 30, 2019 VIDEOS | EP LAB | JULY 26, 2019 VIDEO: What Electrophysiologists Need From CT Imaging Prior to AF and VT Ablations Mark Ibrahim, M.D., F read more News | Radiation Therapy | August 02, 2019 Varian Showcases Cancer Care Systems and Software at AAPM 2019 Varian showcased systems and software from its cancer care portfolio, including the Identify Guidance System, at the… read more The top piece of content in July was a video interview explaining how Princess Margaret Cancer Center is using machine learning to create automated treatment plans. This was a hot topic at the American Association of Physicists in Medicine (AAPM) 2019 meeting in July.  Siemens Go.Top CT scanner at SCCT19Video Player is loading.Play VideoPlayMuteCurrent Time 0:00/Duration 1:05Loaded: 15.14%Stream Type LIVESeek to live, currently playing liveLIVERemaining Time -1:05 Playback Rate1xChaptersChaptersDescriptionsdescriptions off, selectedCaptionscaptions settings, opens captions settings dialogcaptions off, selectedAudio Trackdefault, selectedFullscreenThis is a modal window.Beginning of dialog window. Escape will cancel and close the window.TextColorWhiteBlackRedGreenBlueYellowMagentaCyanTransparencyOpaqueSemi-TransparentBackgroundColorBlackWhiteRedGreenBlueYellowMagentaCyanTransparencyOpaqueSemi-TransparentTransparentWindowColorBlackWhiteRedGreenBlueYellowMagentaCyanTransparencyTransparentSemi-TransparentOpaqueFont Size50%75%100%125%150%175%200%300%400%Text Edge StyleNoneRaisedDepressedUniformDropshadowFont FamilyProportional Sans-SerifMonospace Sans-SerifProportional SerifMonospace SerifCasualScriptSmall CapsReset restore all settings to the default valuesDoneClose Modal DialogEnd of dialog window.Close Modal DialogThis is a modal window. This modal can be closed by pressing the Escape key or activating the close button. AAPM Report No 220. Use of Water Equivalent Diameter for Calculating Patient Size and Size-Specific Dose Estimates (SSDE) in CT Report of AAPM Task Group 220. American Association of Physicists in Medicine, 2014. Feature | Radiation Dose Management | July 15, 2019 | Niki Fitousi, Ph.D., and An Dedulle Can CT Image Truncation Cause False Dose Alerts? Research study suggests image truncation could lead to a larger patient being falsely identified as “standard-sized” and generate a dose alertlast_img

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