[Intl_DxMedPhys] TJC acquisition monitor requirements

[Douglas Pfeiffer]

I guess I have to question how important this is, in the grand scheme. If the internal calipers are correct, does the aspect ratio being off impact anything? Yes, we do the measurement, and that is a reasonable interpretation of this TJC requirement, but I can’t help but wonder why this one matters much. I’m happy to be educated if I’m missing something!

Best regards,
Doug



Douglas Pfeiffer, MS, DABR FACR, FAAPM (he/him)
Medical Physicist, Radiation Safety Officer
Boulder Community Health
xraydoug at me.com
303.415.7515

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The opinions expressed in this message are the product of the gray and white matter loitering in my cranium. I speak for myself and no one else, unless I say otherwise.

> On Sep 23, 2026, at 7:28 AM, Little, Kevin <Kevin.Little at osumc.edu> wrote:
> 
> Hi Doug,
>  
> We use the TG-18 <https://urldefense.com/v3/__https://aapm.onlinelibrary.wiley.com/doi/10.1118/1.1861159__;!!KGKeukY!zgTSlfKsb3VeeyrH7YQ5-5_CYxfPGVYxiCUSyDaKeqROvWA64QL0YXKJYqkjwzO39wwZjD-GrSycCHo-Z04Nq087KCunfKAN--2l$ > geometric distortion test. Essentially, we are looking for an incorrect aspect ratio (which we have found, especially for replacement monitors). We use a ruler to measure the same number of squares on the SMPTE or TG-18 QC pattern in both directions. Then we calculate the percent difference, using the smallest measurement as the reference. TG-18 says that operator’s consoles are secondary displays for everything other than contrast response, so the limit is 5%.
>  
> Kevin
>  
>  
> Kevin J Little, PhD, DABR, DABSNM, CIIP <>
> Associate Professor
> Imaging Medical Physics Residency Program Director
> The Ohio State University Wexner Medical Center
> Department of Radiology
> 395 W 12th Avenue, 4th Fl, Columbus, OH, 43210
> ImagingPhysics at osumc.edu <mailto:ImagingPhysics at osumc.edu>
> On-call Physicist: Internal link <https://webxchange.osumc.edu/webxchange/ViewProfile.aspx?profileid=08701 > or call 614-293-7243,8701#
>  
>  
> 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 Douglas Pfeiffer via Intl_dxmedphys_wd_osu_list
> Sent: Wednesday, September 23, 2026 8:31 AM
> To: DxMedPhys List <intl_dxmedphys_wd_osu_list at lists.osu.edu <mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>>
> Subject: [Intl_DxMedPhys] TJC acquisition monitor requirements
>  
> Good morning! I just received a document to prepare us for upcoming TJC inspections. It includes the following: My question is about the last item - spatial accuracy. I’ve never measured spatial accuracy on an acquisition display, and I don’t
> Good morning!
>  
> I just received a document to prepare us for upcoming TJC inspections. It includes the following:
> <image001.png>
>  
> My question is about the last item - spatial accuracy. I’ve never measured spatial accuracy on an acquisition display, and I don’t remember anyone ever talking about it. The only time I could imagine it being an issue at all is during MR- and CT-guided biopsies, but that is accuracy of the system calipers and not a function of the display. What are folks doing with this one?
>  
> Best regards,
> Doug
>  
>  
>  
> Douglas Pfeiffer, MS, DABR FACR, FAAPM (he/him)
> Medical Physicist, Radiation Safety Officer
> Boulder Community Health
> xraydoug at me.com <mailto:xraydoug at me.com>
> 303.415.7515
>  
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>  
> The opinions expressed in this message are the product of the gray and white matter loitering in my cranium. I speak for myself and no one else, unless I say otherwise.

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