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Precisely. In mammography, just need to remember to protect the detector. Best regards, Doug Douglas Pfeiffer, MS, DABR FACR, FAAPM (he/him) 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;">Precisely. In mammography, just need to remember to protect the detector.<div><br id="lineBreakAtBeginningOfMessage"><div>
<div dir="auto" style="caret-color: rgb(0, 0, 0); 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; text-decoration: none; overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><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; overflow-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; overflow-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 (he/him)</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="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div style="overflow-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></div>
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<div><br><blockquote type="cite"><div>On Jun 3, 2026, at 9:31 AM, Bob Kobistek <bob@rjkmedphys.com> wrote:</div><br class="Apple-interchange-newline"><div><div>Yep, but for stuff like measuring CT beam collimation it doesn't matter. Crank up the mAs to get a good image, then take an image at half the mAs to use as a reference for FWHM. Sensitivity and fog level shouldn't matter<br><br><br>Robert J. Kobistek, MS, FACR, DABR, MRSE(MRSC™)<br>Medical Physicist<br>RJK Medical Physics, Inc.<br>440-463-7879<br><br>-----Original Message-----<br>From: Douglas Pfeiffer <xraydoug@me.com> <br>Sent: Wednesday, June 3, 2026 11:06 AM<br>To: Nicole Ranger <nicoletranger@yahoo.com><br>Cc: Bob Kobistek <bob@rjkmedphys.com>; DxMedPhys List <intl_dxmedphys_wd_osu_list@lists.osu.edu><br>Subject: Re: [Intl_DxMedPhys] Gafchromic film<br><br>Yup. It just loses sensitivity, in my experience.<br><br><br>Doug<br>-------------<br>Sent from my iPhone - please excuse any typos that slip through!<br><br><blockquote type="cite">On Jun 3, 2026, at 9:01 AM, Nicole Ranger via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list@lists.osu.edu> wrote:<br><br>Thanks Bob. I used large sheets in the past to assess skin dose distributions in fluoro procedures and the results were informative but baselines mattered there. Glad to know the consensus is that they can be used almost indefinitely for QC.<br><br>Nicole<br><br><br>Sent from my iPhone<br><br><blockquote type="cite">On Jun 3, 2026, at 11:55 AM, Bob Kobistek <bob@rjkmedphys.com> wrote:<br><br>I'd say as long as you can see a useable image, keep using the film. I left some sheets in my hot car over last summer. The sheets are much darker than new sheets, but I'm still using them for CT collimation testing. I can even scan and locate the FWHM with no problems.<br><br><br>Robert J. Kobistek, MS, FACR, DABR, MRSE(MRSC™) Medical Physicist RJK <br>Medical Physics, Inc.<br>440-463-7879<br><br>-----Original Message-----<br>From: Intl_dxmedphys_wd_osu_list <br><intl_dxmedphys_wd_osu_list-bounces+bob=rjkmedphys.com@lists.osu.edu> <br>On Behalf Of Nicole Ranger via Intl_dxmedphys_wd_osu_list<br>Sent: Wednesday, June 3, 2026 9:33 AM<br>To: DxMedPhys List <intl_dxmedphys_wd_osu_list@lists.osu.edu><br>Subject: [Intl_DxMedPhys] Gafchromic film<br><br>Good morning list,<br><br>I’ve used Gafchromic film extensively in the past in a dosimetry context where cumulative exposure during storage was important but for the Gafchromic that you use for imaging QC purposes (CT, Mammo, etc…) where the baseline exposure is less important so long as there is adequate contrast, what would you consider to be a useful timeframe before the film is less useful? Just wondering if there is any downside when buying a box. We have relatively fewer devices here than I have had to support in the past so I’m not sure how quickly I will go through this stuff.<br><br>TIA<br>Nicole<br><br><br>Sent from my iPhone<br></blockquote><br></blockquote></div></div></blockquote></div><br></div></body></html>