[Intl_DxMedPhys] CT Number Deviations on Siemens Force and Alpha – ACR Phantom Failures

Thu Jul 24 15:35:35 EDT 2025

Hi All,

Not sure if this is related. I had similar issues for head scans (abdomen was fine) on X.ceed.

I did acceptance testing of a X.ceed early last week. I did head scans using Hr44 and Hr40 with iBHC (iterative beam hardening correction) on and off. My results are below. iBHC is used clinically. I did shut ADMIRE off.
[cid:image001.png at 01DBFC95.327A3CC0]

Longer story – I had perhaps a similar issue on a new Flash unit in 2023. In that case I was told by the Applications folks to adjust the Cupping Correction from 0 to 1. (I don’t think it had iHBC and that machine is hours away from me). In that case it was only Bone that was out. We did a side-by-side comparison with the radiologists and they preferred Cupping 1. Both are Hr40 and ADMIRE off.
[cid:image002.png at 01DBFC95.D8EFC340]
I found the same issue with a Force scanner this past January. (Hr40 kernel and Admire off.) I don’t know if this Force has iHBC and I have not had a chance to check yet.
[cid:image003.png at 01DBFC96.EB420CF0]

Kind regards,

Thor Bjarnason, PhD, PEng, FCCPM
Medical Physicist
Interior Health, Kelowna, BC
Office: (250) 980-6157 | Mobile: (250) 826-0722
Thor.Bjarnason at interiorhealth.ca

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+thor.bjarnason=interiorhealth.ca at lists.osu.edu> On Behalf Of Szczykutowicz, Timothy P via Intl_dxmedphys_wd_osu_list
Sent: 24 July 2025 8:47 AM
To: Imendra Ranatunge <ranatunge at gmail.com>; Kalpana M. Kanal <kkanal at uw.edu>
Cc: intl_dxmedphys_wd_osu_list at lists.osu.edu
Subject: Re: [Intl_DxMedPhys] CT Number Deviations on Siemens Force and Alpha – ACR Phantom Failures

It is Audi mode. (using a special kernel for passing tests) 😉 Must be a German thing, albeit Canon also has you do this in terms of beam collimation and slice thickness for their specifications (they want you to use a ridiculous collimation
It is Audi mode. (using a special kernel for passing tests) 😉

Must be a German thing, albeit Canon also has you do this in terms of beam collimation and slice thickness for their specifications (they want you to use a ridiculous collimation we would never use on patients for their noise and LCD measurements)

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

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+tszczykutowicz=uwhealth.org at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list-bounces+tszczykutowicz=uwhealth.org at lists.osu.edu>> On Behalf Of Imendra Ranatunge via Intl_dxmedphys_wd_osu_list
Sent: Thursday, July 24, 2025 9:24 AM
To: Kalpana M. Kanal <kkanal at uw.edu<mailto:kkanal at uw.edu>>
Cc: intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: Re: [Intl_DxMedPhys] CT Number Deviations on Siemens Force and Alpha – ACR Phantom Failures

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Thank you. Yes, I used QIR as well. On Thu, Jul 24, 2025 at 9: 21 AM Kalpana M. Kanal <kkanal@ uw. edu> wrote: That's what was recommended to us as well for any measurements. We tested our Alpha last week and had no issues. Kalpana Kalpana
Thank you. Yes, I used QIR as well.

On Thu, Jul 24, 2025 at 9:21 AM Kalpana M. Kanal <kkanal at uw.edu<mailto:kkanal at uw.edu>> wrote:
That's what was recommended to us as well for any measurements. We tested our Alpha last week and had no issues.

Kalpana

Kalpana M. Kanal, PhD, DABR, FACR, FAAPM, FSABI

Director, Diagnostic Physics Section and Resident Education

Program Director, Imaging Physics Residency Program

Professor, Radiology

Affiliate Faculty, Harborview Injury Prevention Center (HIPRC)

Adj. Professor, Oral Medicine

University of Washington  | 1959 ne pacific street | box 357987 | seattle, wa 98195-7987 |

office location: 222F Portage Bay Bldg

email: kkanal at uw.edu<mailto:kkanal at uw.edu> | v: 206-616-9166 | pg: 206-680-6391 | f: 206-543-8356

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From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+kkanal=uw.edu at lists.osu.edu<mailto:uw.edu at lists.osu.edu>> on behalf of Shane McCotter 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>>
Sent: Thursday, July 24, 2025 7:17:34 AM
To: Imendra Ranatunge <ranatunge at gmail.com<mailto:ranatunge at gmail.com>>
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Subject: Re: [Intl_DxMedPhys] CT Number Deviations on Siemens Force and Alpha – ACR Phantom Failures

Not sure if this will help, but try using the Quantative recon method (if I remember right). Had this issue with a Siemens before and apps recommended that recon. Shane Sent from my iPhone On Jul 24, 2025, at 8: 37 AM, Imendra Ranatunge via Intl_dxmedphys_wd_osu_list
Not sure if this will help, but try using the Quantative recon method (if I remember right). Had this issue with a Siemens before and apps recommended that recon.

Shane

Sent from my iPhone

On Jul 24, 2025, at 8:37 AM, Imendra Ranatunge 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:

Hi All, I’m encountering an issue with a couple of my Siemens CT scanners—specifically the Force and Alpha models. Several of my CT number measurements using the ACR phantom are failing for air, water, and bone. Some units fail all three, while

Hi All,

I’m encountering an issue with a couple of my Siemens CT scanners—specifically the Force and Alpha models. Several of my CT number measurements using the ACR phantom are failing for air, water, and bone. Some units fail all three, while others only one or two.

I tried placing a CTDI phantom adjacent to the ACR phantom, but it showed no improvement.

I reported the issue to Siemens. They performed a constancy test and stated that the units were functioning normally. However, my CT number results are still outside acceptable limits. In my experience, service engineers are often reluctant to perform time-consuming calibrations unless specifically requested.

Has anyone experienced this before? If so, do you know which specific calibration or adjustment Siemens needs to perform to correct these CT number inaccuracies?

Imendra
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