[Intl_DxMedPhys] [EXTERNAL] DECT gout studies

Thu Jun 11 12:16:46 EDT 2026

Awesome Bill! Thanks for doing that. I don't know of any other head to head comps like that.

Energy separation doesn't (or at least mathematically should not) affect quantification tasks. Worse separation would just make your data noisier. Going back to the seminal paper by Alverez and Macovski https://urldefense.com/v3/__https://iopscience.iop.org/article/10.1088/0031-9155/21/5/002/meta__;!!KGKeukY!yAahBjipHNwJJkSocG-itP0idojkYVEGbeMi6crf8Ms1g522ElQzbzjZrrZt-yuXg9xw-qg98WvUPAaxY2iylIwBqKsQRqmuxlJQLYq_68tbfQU_Tg$  the closer the energy measurements to more the noise. But mathematically, so long as you get two different energies, you can decompose onto the basis functions. For systems with very poor separation (lets pick on Philips dual layer) the noise will be way higher (hence philips spectral images look like a nuclear medicine study - their engineers and scientists had to apply a lot of denoising see for example some images in this paper https://urldefense.com/v3/__https://academic.oup.com/bjr/article-abstract/91/1085/20170351/7451909__;!!KGKeukY!yAahBjipHNwJJkSocG-itP0idojkYVEGbeMi6crf8Ms1g522ElQzbzjZrrZt-yuXg9xw-qg98WvUPAaxY2iylIwBqKsQRqmuxlJQLYq_68tRKIvktg$ ). For fast switching, and the various flavors of dual source ( by flavors I mean different tube potential pairings and filtrations) there will be differences in energy separation for sure. I don't go in for basic physics comparisons on their dual energy ratios because it really matters how the vendors denoise the data and how their gout thresholds work. So it is kind of a waste of time to characterize DE ratio to characterize clinical performance of system a and system b when there are downstream denoising and non-linear gout tophi detection algorithms at play. For example, the Mayo group showed the DE ratio of the Alpha was worse than the force when it first came out...but the alpha was making way nicer images (enter benefits of PC for noise and QIR for noise etc.) - the DE ratio didn't tell the entire story.

For Gout, you need higher resolution to not blur the CT numbers of the tophi which make all the threshold setting very complicated, so the best most reliable algorithm for gout tophi is going to come from the vendor that can produce higher resolution low noise recons with reproducible CT numbers. I think to date, siemens has done a better job on providing users with canned protocols and threshold setting recommendations on their advanced visualization toolkit (syngo via). But I don't know if that also means they won the noise-resolution-reproducible battle. This is why MSK readers need experience with these maps...so they can read through all the BS tophi that light up. In my experience, I have seen happy rads on either technology who invest the time to play with the settings (for example the DE ratio and HU thresholds on syngo via) and invest the time gaining confidence with known true positive clinical cases to train themselves how to avoid false positives.
(my practical advice is to not waste time with phantoms, get a positive case and scan it and then schedule a meeting with apps and a msk rad to play with it - for both siemens or GE)

PC should make all this way better, because the resolution in spectral mode (at least for GE) is so much higher and the CT number and iodine values (at least for GE) is way more robust. (I say at least for GE here because that is the scanner I have, I would have to bet the alpha is similar). So in general, I think we should do better for gout on PC technology.

I just emailed our gout protocol for GE to Stephanie, I am getting our latest AW parms now and will post instructions and parms when I have them.

Timothy P. Szczykutowicz, Ph.D., DABR
Professor
Departments of Radiology, Medical Physics and BME
University of Wisconsin Madison
Cell# 1-716-560-7751<tel:(716)%20560-7751>
Office# 1-608-263-5729
he/him/his

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From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu> on behalf of William Sensakovic via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
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To: intl_dxmedphys_wd_osu_list at lists.osu.edu <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: Re: [Intl_DxMedPhys] [EXTERNAL] DECT gout studies

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Hello, we have two posters coming up at AAPM related to creating a phantom for assessing CT gout identification and how different parameters impact final identification accuracy. We also will have an educational and scientific poster at RSNA
Hello,
we have two posters coming up at AAPM related to creating a phantom for assessing CT gout identification and how different parameters impact final identification accuracy. We also will have an educational and scientific poster at RSNA about optimization if they get accepted (hint hint to reviewers for the conference that happen to be on the listserv...timely topic! 🙂).
Anyway, for the GE system we found that the main thing is changes to the software parameters (the method was relatively insensitive to acquisition and reconstruction as long as you are using a low noise recon kernel).
Unfortunately, we only have a couple of patients we were able to test this on.
We are currently hoping to find collaborators who would be willing to apply default and our optimized settings and confirm improvement based on longitudinal patient outcome.
If there is interest in collaborating, please let me know!
best,
bill

William F. Sensakovic, PhD, DABR, MRSC

Founder - Telerad Physics Teaching, LLC<https://urldefense.com/v3/__http://www.teleradphysics.com/__;!!KGKeukY!yEMgZD_OyLLdkzQC8lOo0nkLIzJp7FI5xteXyDNvLTJxAbbdSC_btPOvzWS3G0JKgwsGtG-FCJoShH9BWqXuwAtbwXA9rKMUencCpCHK$>

Chair, Medical Physics - Mayo Clinic (Arizona)

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From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+wfsensak=outlook.com at lists.osu.edu> on behalf of Hoy, Andrew via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Sent: Thursday, June 11, 2026 7:12 AM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu <intl_dxmedphys_wd_osu_list at lists.osu.edu>; Stephanie M. Leon <Stephanie.M.Leon at hitchcock.org>
Subject: Re: [Intl_DxMedPhys] [EXTERNAL] DECT gout studies

I know Stephanie asked for offline feedback, but I would love to hear from anyone who feels good about their gout protocols/workflow on the GE Apex. It has been a few years now since we tried implementing dual energy gout imaging, but we never
I know Stephanie asked for offline feedback, but I would love to hear from anyone who feels good about their gout protocols/workflow on the GE Apex.
It has been a few years now since we tried implementing dual energy gout imaging, but we never got to a point where our radiologists felt confident in identifying tophi.  We had GE in house to help set things up and had several remote meetings to go over our scans and tweak settings but ultimately abandoned the project.  We could never dial in cutoffs to get both the sensitivity and specificity to make it worthwhile.
At the time (I haven’t looked in a few years not), all the literature on dual energy gout imaging was done on a dual tube system.  My conclusion was that GE’s dual energy solution is technically really cool, but it just doesn’t get the x-ray spectra separation that is needed for reliable material decomposition.  Fast kV switching simply isn’t the same as two tubes with different kVp and filters.
I am certainly not the expert in CT physics and would love to hear what others who are happy with their outcomes are doing.
Thank you,
Andrew

Andrew R. Hoy, PhD, DABR

Radiation Safety Officer

Diagnostic Medical Physicist

Office (605) 312-1429

Cell: (480) 329-5552

Sanford USD Medical Center

Sioux Falls, SD

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From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu> on behalf of Stephanie M. Leon via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Sent: Thursday, June 11, 2026 8:38 AM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: [EXTERNAL] [Intl_DxMedPhys] DECT gout studies

Hello all, If anyone has experience with DECT processing of gout studies on a GE Apex, can you please contact me off-list? I’m trying to figure out settings and workflow. Thanks, Stephanie M. Leon, PhD, DABR, DABSNM Chief of Diagnostic

Hello all,

If anyone has experience with DECT processing of gout studies on a GE Apex, can you please contact me off-list? I’m trying to figure out settings and workflow.

Thanks,

Stephanie M. Leon, PhD, DABR, DABSNM

Chief of Diagnostic Medical Physics

Associate Professor of Radiology

Tel (603) 650-3796
Dartmouth-Health.org

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