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Sorry, Enoch. Here’s one from one of my systems, in phantom and in air. Best regards, Doug Douglas Pfeiffer, MS, DABR FACR, FAAPM Medical Physicist, Radiation Safety Officer Boulder Community Health xraydoug@ me. com 303. 415. 7515 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-</div>
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<meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">Sorry, Enoch.<div><br></div><div>Here’s one from one of my systems, in phantom and in air.</div><div><br id="lineBreakAtBeginningOfMessage"><div>
<div id="signature"><div style="color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><div style="orphans: 2; widows: 2;">Best regards,</div><div style="orphans: 2; widows: 2;">Doug</div><div style="orphans: 2; widows: 2;"><br></div><div style="orphans: 2; widows: 2;"><br></div><div style="orphans: 2; widows: 2;"><br></div><div style="orphans: 2; widows: 2;">Douglas Pfeiffer, MS, DABR FACR, FAAPM</div><div style="orphans: 2; widows: 2;">Medical Physicist, Radiation Safety Officer</div><div style="orphans: 2; widows: 2;">Boulder Community Health</div><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px;"><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px;"><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px;"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div>xraydoug@me.com</div><div>303.415.7515</div><div><br class="webkit-block-placeholder"></div><div>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-</div><div><br class="webkit-block-placeholder"></div><div>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.</div></div></div></span></span></span></div></div></div></div>
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<div><br><blockquote type="cite"><div>On Aug 19, 2025, at 10:19 AM, Enoch Tung via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list@lists.osu.edu> wrote:</div><br class="Apple-interchange-newline"><div><meta charset="UTF-8"><div class="WordSection1" style="page: WordSection1; caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;">Hi list,<o:p></o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><o:p> </o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;">Re-circulating this to see if anyone has examples of non-uniformities visible through air scans performed.<o:p></o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><o:p> </o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;">I don’t know if the lack of response was due to this being an uncommonly performed approach, visible artifact manifests rarely, or me choosing the wrong time to ask the question just before the AAPM annual meeting.<o:p></o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><o:p> </o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;">I appreciate any insight or help anyone may have.<o:p></o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><o:p> </o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;">Thanks,<o:p></o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;">Enoch<o:p></o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><o:p> </o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><o:p> </o:p></div><div><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(225, 225, 225) currentcolor currentcolor; border-image: none; padding: 3pt 0in 0in;"><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><b><span style="font-size: 11pt; font-family: Calibri, sans-serif;">From:</span></b><span style="font-size: 11pt; font-family: Calibri, sans-serif;"><span class="Apple-converted-space"> </span>Enoch Tung<br><b>Sent:</b><span class="Apple-converted-space"> </span>Friday, July 25, 2025 12:49 PM<br><b>To:</b><span class="Apple-converted-space"> </span><a href="mailto:intl_dxmedphys_wd_osu_list@lists.osu.edu" style="color: rgb(70, 120, 134); text-decoration: underline;">intl_dxmedphys_wd_osu_list@lists.osu.edu</a><br><b>Subject:</b><span class="Apple-converted-space"> </span>CT Artifact Evaluation Absent Large Poly Disk - air scan<o:p></o:p></span></div></div></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><o:p> </o:p></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Hi list,<o:p></o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;"><o:p> </o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Does anyone have examples of artifacts that can be observed in performing air scans for the comprehensive SFOV in the absence of a large uniformity phantom?<o:p></o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;"><o:p> </o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">I’m referencing the alternative method as suggested by the ACR CT QC Manual (<a href="https://urldefense.com/v3/__https://accreditationsupport.acr.org/support/solutions/articles/11000056188-quality-control-ct__;!!KGKeukY!1_cZvcWoFXPo6GIt5QbdTx3q5w7z1viB6JqJitALJLFU0p1VxDrNOh7TkddRDIK5omcY84u7R2grKKZsQRMt7g5JDMLeg0utirfBKQH1W52m$" style="color: rgb(70, 120, 134); text-decoration: underline;">https://accreditationsupport.acr.org/support/solutions/articles/11000056188-quality-control-ct</a>). The exact instruction are:<o:p></o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><b><span style="font-size: 11pt;">Artifact Evaluation Absent Large Poly Disk<a name="_msoanchor_1"></a><o:p></o:p></span></b></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Should your facility not have a large poly disk available to perform artifact evaluation on the scan field of view (SFOV) as required, this approach provides a method to qualitatively evaluate the level of non-uniformities in the SFOV outside of the phantom FOV.<b> </b><o:p></o:p></span></div><ol start="1" type="a" style="margin-bottom: 0in; margin-top: 0in;"><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Taking care to center the phantom to the SFOV, perform the usual daily QC phantom scan using the smallest T allowed by the maximum NxT <o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Perform artifact evaluation using <a href="https://urldefense.com/v3/__https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/Specialties/Medical-Physics-Resources__;!!KGKeukY!1_cZvcWoFXPo6GIt5QbdTx3q5w7z1viB6JqJitALJLFU0p1VxDrNOh7TkddRDIK5omcY84u7R2grKKZsQRMt7g5JDMLeg0utirfBKWAMvXQ2$" style="color: rgb(70, 120, 134); text-decoration: underline;">ACR CT QC manual</a> method to determine if there are potentially clinically significant artifacts over the phantom FOV (if artifacts are seen, use clinical image significance evaluation method below)<o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">After verifying the absence of such artifacts over the phantom FOV, at least monthly perform an air scan using a modified version of the daily QC protocol that uses the largest clinical SFOV available<o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">To evaluate the L SFOV images for potentially clinically significant artifacts outside of the phantom FOV, set a window width of approximately 100 HU and a window level of approximately -1000 HU<o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Draw a 20 cm diameter ROI in the center of the image<o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Review all images qualitatively comparing the level of visualized non-uniformities outside the ROI to that inside the ROI<o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Consider a similar level of non-uniformities to be acceptable<o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">If there is an increased level of non-uniformities seen outside the ROI, review clinical scans to determine if artifacts are clinically significant<o:p></o:p></span></li><li class="MsoNormal" style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Clinical scans reviewed should be of the large scan field of view using all typical reconstruction window and level settings<o:p></o:p></span></li></ol><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;"><o:p> </o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">I’m interested how non-uniformities will show as neither myself nor our technologist have been able to observe such.<o:p></o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;"><o:p> </o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Thanks,<o:p></o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;">Enoch<o:p></o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><span style="font-size: 11pt;"><o:p> </o:p></span></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><b><span style="font-size: 10pt; font-family: Muli;"><o:p> </o:p></span></b></div><div style="margin: 0in; font-size: 12pt; font-family: Aptos, sans-serif;"><b><span style="font-size: 10pt; font-family: Muli;">Enoch Tung<span class="Apple-converted-space"> </span></span></b><span style="font-size: 10pt; font-family: Muli;">|<b><span class="Apple-converted-space"> </span></b>Medical Physicist (Diagnostic and Health), Radiation Safety Officer, Laser Safety Officer</span><span style="font-size: 10pt; font-family: Muli;"><o:p></o:p></span></div><div style="margin: 0in; 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