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<p class="MsoNormal"><span style="font-size:12.0pt">Hi Doug,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">We use the <a href="https://urldefense.com/v3/__https://aapm.onlinelibrary.wiley.com/doi/10.1118/1.1861159__;!!KGKeukY!0hVAGTUjL-BxQi0GIhsZuSFfh59iAhpgWI1vKOimiDD_9gfyZBTnfpan8_PGl7dnBR-TJ4IoQK8vDxyNoL4pVVJbz2xD2zcFDCS5LScxhcgpylc$">
TG-18</a> 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%.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Kevin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><a name="x__MailAutoSig"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#BB0000;background:white">Kevin J Little, PhD, DABR, DABSNM, CIIP</span></b></a><span style="mso-bookmark:x__MailAutoSig"></span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333"><br>
<span style="background:white">Associate Professor</span><br>
<span style="background:white">Imaging Medical Physics Residency Program Director</span><br>
</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#BB0000;background:white">The Ohio State University Wexner Medical Center</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333;background:white">Department of Radiology</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333"><br>
<span style="background:white">395 W 12th Avenue, 4th Fl, Columbus, OH, 43210</span></span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black;background:white"><a href="mailto:ImagingPhysics@osumc.edu"><span style="color:blue">ImagingPhysics@osumc.edu</span></a></span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333;background:white;mso-ligatures:standardcontextual">On-call Physicist:
</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black;background:white;mso-ligatures:standardcontextual"><a href="https://webxchange.osumc.edu/webxchange/ViewProfile.aspx?profileid=08701"><span style="color:blue">Internal link</span></a></span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#333333;background:white;mso-ligatures:standardcontextual"> or
call </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black;background:white;mso-ligatures:standardcontextual">614-293-7243,8701#</span><span style="font-size:12.0pt;mso-ligatures:standardcontextual"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces@lists.osu.edu>
<b>On Behalf Of </b>Douglas Pfeiffer via Intl_dxmedphys_wd_osu_list<br>
<b>Sent:</b> Wednesday, September 23, 2026 8:31 AM<br>
<b>To:</b> DxMedPhys List <intl_dxmedphys_wd_osu_list@lists.osu.edu><br>
<b>Subject:</b> [Intl_DxMedPhys] TJC acquisition monitor requirements<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-line-height-alt:.75pt"><span style="font-size:1.0pt;color:white">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<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Good morning!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">I just received a document to prepare us for upcoming TJC inspections. It includes the following:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><img border="0" width="640" height="116" style="width:6.6666in;height:1.2083in" id="Picture_x0020_1" src="cid:image001.png@01DD4B3D.F162B890"></span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">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?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Best regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Doug<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Douglas Pfeiffer, MS, DABR FACR, FAAPM (he/him)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Medical Physicist, Radiation Safety Officer<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Boulder Community Health<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><a href="mailto:xraydoug@me.com">xraydoug@me.com</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">303.415.7515<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">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.<o:p></o:p></span></p>
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