[Intl_DxMedPhys] EXT MSG Re: Siemens CT IQ level

Fri Jan 9 11:58:52 EST 2026

It looks like this issue has been pretty well-covered, but I'll pile on (not up) anyway:

  *
As far as I can tell, the "CARE keV optimized for" field does not affect the IQ/QRM crosswalk on EID scanners in the way that it does on the Alpha.  I presume this is because the PCCT has a default VMI recon with inherent CNR properties, while EID recons do not have a this "contrast knob"

  *
Ostensibly the function of the IQ level parameter is to maintain the same quality of images when translating protocols across SomX scanners of differing models.  Here's a screen grab of a routine abdomen/pelvis WO on 4 different scanners with the IQ level set to 150.  This seems to indicate that the goTop scanner requires ~10% less dose than the other (higher level) scanners to provide 150 "image qualities"  :
     *
[cid:3a90c477-046e-4a01-931b-28516f5746f3]
  *
Our first EID scanner on the Somaris X platform was a go.Top.  When we grabbed those protocols and transferred to the X.Cite, we found a global 17% increase in IQ level (dose-modulated) and mAs (fixed) for all protocols, which went against my understanding of the translatability of protocols across models.  I.e the source protocol would have an IQ level of 100, and instead of transferring that 100 over to the X.Cite, the destination protocol was uploaded with an IQ level of 117 automatically.  I looked at phantom data on both scanners using a fixed dose, and noise levels were pretty well-matched.  Thus, I couldn't find a rationale for increasing dose across the board on our X.Cite scanner.  I reached out to Siemens about this and was essentially re-told the definition of IQ level.  I could not get a good answer on how "image qualities" are measured, and thus don't know if my simple noise measurement was sufficient.

  *
Echoing Kevin's reply - because i don;t know what an "IQ" is, my protocol work consists of adjusting IQ level as the only tunable reference quality/dose knob, but looking at the quality reference mAs while doing so

  *
Stephanie - we have several EID and one PCCT on somaris X (with more PCCT flavors to be installed over the next year). Happy to help out with a project.

Steve

________________________________
From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+steve.bache=duke.edu at lists.osu.edu> on behalf of Ryan Fisher via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Sent: Friday, January 9, 2026 11:32 AM
To: Stephanie M. Leon <Stephanie.M.Leon at hitchcock.org>; intl_dxmedphys_wd_osu_list at lists.osu.edu <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: Re: [Intl_DxMedPhys] EXT MSG Re: Siemens CT IQ level

Semi-related shameless plug, but we have a session at the Spring Clinical Meeting (3/21-24 in Orlando) on setting up a clinical PCCT program, as well as another one on TG-299 – QC in Multi-Energy CT. Ryan From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces@ lists. osu. edu>

Semi-related shameless plug, but we have a session<https://urldefense.com/v3/__https://site.aapm.org/docs/default-source/spring-clinical/2026scm-paag.pdf__;!!KGKeukY!3oJR9QcSl-g2zdD0yPkzfHBhwcMCHIMYG9Eg6aAQXuhyt0XY5uN9cK8f0O_H0JLjLXgTZz2aQzP_I26XNYLw18rupZIzdByZTLod82R8HLjf$> at the Spring Clinical Meeting<https://urldefense.com/v3/__https://site.aapm.org/spring-clinical/spring-clinical-home__;!!KGKeukY!3oJR9QcSl-g2zdD0yPkzfHBhwcMCHIMYG9Eg6aAQXuhyt0XY5uN9cK8f0O_H0JLjLXgTZz2aQzP_I26XNYLw18rupZIzdByZTLod802mV4nO$> (3/21-24 in Orlando) on setting up a clinical PCCT program, as well as another one on TG-299 – QC in Multi-Energy CT.

Ryan

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
Sent: Friday, January 9, 2026 11:23 AM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu
Subject: Re: [Intl_DxMedPhys] EXT MSG Re: Siemens CT IQ level

STOP!

THIS IS AN EXTERNAL EMAIL
This email was originated outside of the MetroHealth System

Take a 3-second pause and ask yourself the following questions:

1. Who is sending me this email? Do I know who this is?
2. Am I expecting this email? Is this out of the ordinary?
3. Why is there a link in the email? Do I trust this link?

THINK
Before You
Click the Link

Thank you everyone for these responses!! Super helpful. I am hearing pretty universally about how IQ level is supposed to work, but no one seems to know how image quality is measured or how well it actually works. Sounds like a super useful

Thank you everyone for these responses!! Super helpful.

I am hearing pretty universally about how IQ level is supposed to work, but no one seems to know how image quality is measured or how well it actually works. Sounds like a super useful research paper, but would require access to a decent number of scanners. Reach out if you have a Somaris 10 scanner (PCCT or EID) and would be interested in working on this!

Stephanie

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu>> On Behalf Of Allan Thomas via Intl_dxmedphys_wd_osu_list
Sent: Friday, January 9, 2026 10:47 AM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: Re: [Intl_DxMedPhys] EXT MSG Re: Siemens CT IQ level **EXTERNAL**

I think the responses so far have provided most of the basic information about IQ level. It is meant to be a more nuanced value that goes beyond a quality reference mAs. Because different Siemens scanners have different bore sizes, filtration,

I think the responses so far have provided most of the basic information about IQ level. It is meant to be a more nuanced value that goes beyond a quality reference mAs. Because different Siemens scanners have different bore sizes, filtration, and dose vs image quality, IQ level is meant to make it easier to transition protocols across multiple scanner platforms. In principle, an IQ level of "X" for a given protocol on Scanner A (e.g. an Alpha Peak) will produce similar image quality on Scanner B (e.g. an X.Cite) using that same protocol. Historically, in order to achieve comparable image quality across two such scanners, a lot of effort would be required on the part of the medical physicist to understand differences in CTDIvol vs mAs, dose vs image quality, impact of bow tie filters, impact of CARE kV, etc.

IQ level is linear with CTDIvol just like mAs is. And each individual protocol, scanner, etc. will have its own relationships for mAs/IQ level. Steve Bache provided some of those specifics to this list for the Alpha Peak some time ago. I provide them again below and have added some data for adult head protocols as well. The data I provide below is for an Alpha Peak scanner on VB10 software. I don't believe CARE Dose4D settings will impact the data I include below because it all reflects information for the "reference size patient." But I can't ensure this is true.

Note that specifically for the Alpha, CARE keV also impacts the mAs/IQ level and eventual target CTDIvol in a given protocol. This is much like CARE kV on EID-CT scanners but also different in that it is tied globally to the protocol for all patients, not a given patient based on their size. If the protocol is set up for "soft tissue with contrast" for CARE keV, all patients will be scanned using the target dose and dose modulation associated with the 60 keV setting. This will not change based on patient size like CARE kV does.

I have not personally done any testing or experiments to see if the concept of IQ level actually achieves its goal: comparable image quality across scanner platforms when the same IQ level is set for a given protocol. But if you desire to know how IQ level relates to quality reference mAs and CTDIvol for any protocol on a Somaris 10 scanner, you can find that information by digging into the dose settings. The actual effective mAs tied to the IQ level that is set and the CTDIvol that is produced for the reference size patient can still be found.

I don't have much experience with Somaris 10 scanners that are EID, but I think the basic principles still apply. The IQ level will dictate a certain quality reference mAs and CTDIvol for the reference size patient, but this will likely change for body vs head, adult vs peds, and with variation in kV (CARE kV settings).

[cid:image001.png at 01DC815B.ACF3AD10]

----------------------------

Allan Thomas, PhD, DABR

Assistant Professor of Radiology

Mallinckrodt Institute of Radiology   |   Washington University School of Medicine

510 S. Kingshighway  |  St. Louis, MO  63110

•:501.529.8496  |  •: allant at wustl.edu<mailto:allant at wustl.edu>

[A close-up of a logo  Description automatically generated]

On Fri, Jan 9, 2026 at 8:39 AM Gauntt, David via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>> wrote:

Stephanie, We have a photon counting Siemens scanner, but if you learn anything about the IQ and dose let me (and the rest of the mailing list) know. I have yet to find anyone at Siemens who knows what affects dose (including the IQ setting). 

Stephanie,

We have a photon counting Siemens scanner, but if you learn anything about the IQ and dose let me (and the rest of the mailing list) know.  I have yet to find anyone at Siemens who knows what affects dose (including the IQ setting).

--

David M. Gauntt, Ph.D.

Associate Professor, Department of Radiology

University of Alabama at Birmingham Medical Center

davidgauntt at uabmc.edu<mailto:davidgauntt at uabmc.edu>

[Text  Description automatically generated with medium confidence]

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+davidgauntt=uabmc.edu at lists.osu.edu<mailto:uabmc.edu at lists.osu.edu>> on behalf of DxMedPhys List <intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>>
Reply-To: "Stephanie M. Leon" <Stephanie.M.Leon at hitchcock.org<mailto:Stephanie.M.Leon at hitchcock.org>>
Date: Thursday, January 8, 2026 at 1:21 PM
To: "Stephanie M. Leon" <Stephanie.M.Leon at hitchcock.org<mailto:Stephanie.M.Leon at hitchcock.org>>, DxMedPhys List <intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>>
Subject: EXT MSG Re: [Intl_DxMedPhys] Siemens CT IQ level

Just to clarify, if it makes a difference, this is not a PCCT scanner. It’s a Pro. Pulse and I’m wondering about a traditional single-energy scan. From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces@ lists. osu. edu> On Behalf

Just to clarify, if it makes a difference, this is not a PCCT scanner. It’s a Pro.Pulse and I’m wondering about a traditional single-energy scan.

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu>> On Behalf Of Stephanie M. Leon via Intl_dxmedphys_wd_osu_list
Sent: Thursday, January 8, 2026 2:04 PM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: [Intl_DxMedPhys] Siemens CT IQ level **EXTERNAL**

Hi all, Apparently the newer Siemens CT scanners have dispensed with reference mAs and now use IQ (image quality) Level. I’m having trouble finding any detail about IQ Level. Is there a way to directly relate it to the old reference mAs,

Hi all,

Apparently the newer Siemens CT scanners have dispensed with reference mAs and now use IQ (image quality) Level. I’m having trouble finding any detail about IQ Level. Is there a way to directly relate it to the old reference mAs, assuming a single-energy scan at the same kVp?

Thanks!

Stephanie Leon

IMPORTANT NOTICE REGARDING THIS ELECTRONIC MESSAGE:

This message is intended for the use of the person to whom it is addressed and may contain information that is privileged, confidential, and protected from disclosure under applicable law. If you are not the intended recipient, your use of this message for any purpose is strictly prohibited. If you have received this communication in error, please delete the message and notify the sender so that we may correct our records.

IMPORTANT NOTICE REGARDING THIS ELECTRONIC MESSAGE:

This message is intended for the use of the person to whom it is addressed and may contain information that is privileged, confidential, and protected from disclosure under applicable law. If you are not the intended recipient, your use of this message for any purpose is strictly prohibited. If you have received this communication in error, please delete the message and notify the sender so that we may correct our records.

IMPORTANT NOTICE REGARDING THIS ELECTRONIC MESSAGE:

This message is intended for the use of the person to whom it is addressed and may contain information that is privileged, confidential, and protected from disclosure under applicable law. If you are not the intended recipient, your use of this message for any purpose is strictly prohibited. If you have received this communication in error, please delete the message and notify the sender so that we may correct our records.

MetroHealth’s Mission: Leading the way to a healthier you and a healthier community through service, teaching, discovery, and teamwork. This email and all attachments that may have been included are intended only for the use of the party to whom/which the email is addressed and may contain information that is privileged, confidential, or exempt from disclosure under applicable law. If you are not the addressee or the employee or agent of the intended recipient, you are hereby notified that you are strictly prohibited from printing, storing, disseminating, distributing, or copying this communication.Contact us<https://urldefense.com/v3/__https://fs26.formsite.com/8dBVlg/sjvmjw2v0c/index.html__;!!KGKeukY!3oJR9QcSl-g2zdD0yPkzfHBhwcMCHIMYG9Eg6aAQXuhyt0XY5uN9cK8f0O_H0JLjLXgTZz2aQzP_I26XNYLw18rupZIzdByZTLod88-v32y3$>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.osu.edu/mailman/private/intl_dxmedphys_wd_osu_list/attachments/20260109/d04f2b44/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 52105 bytes
Desc: image001.png
URL: <https://lists.osu.edu/mailman/private/intl_dxmedphys_wd_osu_list/attachments/20260109/d04f2b44/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.jpg
Type: image/jpeg
Size: 3532 bytes
Desc: image002.jpg
URL: <https://lists.osu.edu/mailman/private/intl_dxmedphys_wd_osu_list/attachments/20260109/d04f2b44/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.png
Type: image/png
Size: 15010 bytes
Desc: image003.png
URL: <https://lists.osu.edu/mailman/private/intl_dxmedphys_wd_osu_list/attachments/20260109/d04f2b44/attachment-0001.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 289508 bytes
Desc: image.png
URL: <https://lists.osu.edu/mailman/private/intl_dxmedphys_wd_osu_list/attachments/20260109/d04f2b44/attachment-0002.png>