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

[Imendra Ranatunge]

Thank you. Yes, I used QIR as well.

On Thu, Jul 24, 2025 at 9:21 AM Kalpana M. Kanal <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 | v: 206-616-9166 | pg: 206-680-6391 | f:
> 206-543-8356
> ------------------------------
> *From:* Intl_dxmedphys_wd_osu_list
> <intl_dxmedphys_wd_osu_list-bounces+kkanal=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>
> *Sent:* Thursday, July 24, 2025 7:17:34 AM
> *To:* Imendra Ranatunge <ranatunge at gmail.com>
> *Cc:* intl_dxmedphys_wd_osu_list at lists.osu.edu <
> intl_dxmedphys_wd_osu_list at lists.osu.edu>
> *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>
> 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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