[Intl_DxMedPhys] TJC acquisition monitor requirements

[Wunderle, Kevin]

It appears to me that the JC requirement only states that spatial accuracy must be “evaluated,” but, in typical JC fashion, it does not define what that means or how it should be assessed. The good part of that is that you get to define what that means and of course document what you are doing to meet that requirement.

I believe a visual assessment using one of the standard test patterns could be reasonably defended. We know what the SMPTE, TG-18, and TG-270 patterns are supposed to look like, and one could document that no warping or other spatial distortion is present in the displayed objects, thereby demonstrating that spatial accuracy was evaluated.

While measurements are probably preferable and more closely aligned with the applicable AAPM reports, I do not read the JC requirement as making them strictly necessary.

All the best,
Kevin W

[The Ohio State University]
Kevin Wunderle, PhD, FAAPM, FACR
Professor, Department of Radiology
Diagnostic Medical Physicist
395 W. 12th Avenue,
Floor 4, Room 410
Columbus, OH, 43210
216-245-5513 Mobile
kevin.wunderle at osumc.edu<mailto:kevin.wunderle at osumc.edu>


From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+kevin.wunderle=osumc.edu at lists.osu.edu> On Behalf Of Douglas Pfeiffer via Intl_dxmedphys_wd_osu_list
Sent: Wednesday, September 23, 2026 9:41 AM
To: Little, Kevin <Kevin.Little at osumc.edu>
Cc: DxMedPhys List <intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: Re: [Intl_DxMedPhys] TJC acquisition monitor requirements

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,
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<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.


On Sep 23, 2026, at 7:28 AM, Little, Kevin <Kevin.Little at osumc.edu<mailto: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

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

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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