[Intl_DxMedPhys] EXT MSG Re: Siemens CT IQ level

Fri Jan 9 10:46:39 EST 2026

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).

[image: image.png]

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

*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

[image: 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> 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
>
>
>
> [image: 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>
> on behalf of DxMedPhys List <intl_dxmedphys_wd_osu_list at lists.osu.edu>
> *Reply-To: *"Stephanie M. Leon" <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>, DxMedPhys
> List <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> *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
> *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,
>
> 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
>
>
>
>
>
>
>
>
>
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> IMPORTANT NOTICE REGARDING THIS ELECTRONIC MESSAGE:
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> This message is intended for the use of the person to whom it is addressed
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