[Intl_DxMedPhys] ACR PET QC Manual Discrepancy

Fri Feb 6 10:18:51 EST 2026

Hmm.  Okay – this is really delving into the weeds.

The bottom line first:  For submission, you have to follow the letter of the law as written in the submission guidelines.  In fact, the system will pre-score your phantom for the reviewer based on the strict interpretation of the submission guidelines and it has no knowledge of the QC Manual.  A sympathetic reviewer could possibly rescue you but don’t’ count on it.

I personally think that the submission criteria should change. Although it’s a nuance, the submission criteria may fail your phantom on two separate metrics for one issue (the overall calibration).

The reason for minimum feature SUVs is to ensure that the scanner and imaging chain can achieve a minimum recovery.  The reason for the range (and so max) for the 25 mm feature is a guard against juicing Dose A .  In other words, the assessment of recovery is supposed to be done for a standard feature to background concentration ratio.

The problem with SUV max is at least twofold – it’s very noisy and it’s vulnerable to aggressive resolution recovery algorithms.  So what can you do about it:

  *   Make sure you are measuring this on the 1-cm thick slices (~3 resliced/restacked or successively averaged native slices).  That will reduce the noise.
  *   Try turning off the resolution recovery  (PSF model) in a re-recon.

If these steps fail to fix the problem, it is possible that your Dose A was too high.  I know that’s supposed to be “checked” with the Test Dose 1 and Test Dose 2 ratio (BTW, the ratio is an inverted and scaled version of the concentration ratio – beware, most people don’t seem to realize that) but I find those values to be at least as noisy as the SUVmax – it’s a challenge to measure with any accuracy in a typical PET hot lab, doses of a few uCi.

And, another piece of advice – take a look at Appendix A, Preparing the PET ACR Phantom for Enhanced
Accuracy, and consider using this dilution scheme to prepare the two doses. I believe that the preparation itself is a huge source of errors.  Using this scheme will guarantee a feature to background ratio of 2.4.  I have prepared a very large number (I’m almost ashamed to say how many) of phantoms using this method and have (almost) never had a 25mm hot cylinder be too hot.

Matt Palmer

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu> On Behalf Of Dylan DeAngelis via Intl_dxmedphys_wd_osu_list
Sent: Friday, February 6, 2026 9:29 AM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu
Subject: [External] Re: [Intl_DxMedPhys] ACR PET QC Manual Discrepancy

Good morning, This is a spiritual follow-up to my earlier email, since it’s related. During recent phantom analysis, I measured the 25mm hot vial SUVmax at about 3. 0. I tried a couple of different slices, and did some troubleshooting,
Good morning,

This is a spiritual follow-up to my earlier email, since it’s related. During recent phantom analysis, I measured the 25mm hot vial SUVmax at about 3.0. I tried a couple of different slices, and did some troubleshooting, but for the sake of this question, let’s say 3.0 was my final best reading.

Per the PET Phantom Testing ACR webpage<https://urldefense.com/v3/__https:/accreditationsupport.acr.org/support/solutions/articles/11000062800-phantom-testing-pet__;!!KGKeukY!ycerDVMq6l5SG5Y8AF_rgX6inScWQH2pW3UsvsaDYLYASMpbnV3ARGgBBZp552HwwyWqyEx2zngfIiecGoQd_zdwiRL6EX0PnBhobGRPrB5z$>, this is a failure, right? From the webpage:

[cid:image002.png at 01DC974F.A79BD310]

But the QC Manual wording is different. Here is the text on page 47:

[cid:image004.png at 01DC974F.A79BD310]

So according to the QC manual, it’s the ratio that must be between 1.87 and 2.91. As it turns out, in my case, the background SUVmean was a little bit higher than 1.0, which brought the ratio down to 2.9. Would this be a pass or a fail?

How are others looking at this? Is it a case of the same value being acceptable for the phantom analysis but not acceptable in an ACR submission?

Thanks,

Dylan DeAngelis, MS, DABR
NYS Licensed Medical Physicist
(Diagnostic Radiological Physics and Medical Nuclear Physics)

Upstate Medical Physics – Diagnostic Radiology, Medical Nuclear & Medical Health Physics, P.C.
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From: Palmer, Matthew R. (BIDMC - Radiology) <mpalmer at bidmc.harvard.edu<mailto:mpalmer at bidmc.harvard.edu>>
Sent: Tuesday, December 9, 2025 12:59 PM
To: Dylan DeAngelis <ddeangelis at upstatemp.com<mailto:ddeangelis at upstatemp.com>>; intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: RE: ACR PET QC Manual Discrepancy

If you’re going to try to evaluate the background SUV with high precision then you need the large cylindrical (3 cm) VOI.  The SUVmean of that small ROI used for accreditation is very noisy and just not a good estimate of background SUV/scanner calibration. We did look at this carefully and  we were aware that it would cause some grief for the physicists who are preparing an accreditation-ready dataset during the annual.  But the small amount of extra work is worth it.  And, our hope is that the ACR PET/Nukes physics committee will see the light and change accreditation submission directions (or just broaden them to allow either) .

The P/F criteria for the annual test BTW, is still +/- 10% but there’s a recommendation to investigate the cause if it falls outside the +/- 5% range.

Matt Palmer

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 Dylan DeAngelis via Intl_dxmedphys_wd_osu_list
Sent: Wednesday, December 3, 2025 12:40 PM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: [External] [Intl_DxMedPhys] ACR PET QC Manual Discrepancy

Good morning, I saw an email chain from earlier this month describing a discrepancy between NM QC manual and ACR website for image submission. In reviewing the new PET manual, my colleagues and I found a similar mismatch, and I’m wondering
Good morning,

I saw an email chain from earlier this month describing a discrepancy between NM QC manual and ACR website for image submission. In reviewing the new PET manual, my colleagues and I found a similar mismatch, and I’m wondering how others interpret this…

On the ACR webpage that details phantom testing, https://urldefense.com/v3/__https://accreditationsupport.acr.org/support/solutions/articles/11000062800-phantom-testing-pet-revised-10-23-2025-__;!!KGKeukY!1nlQrFW3SnaH_OIEj5E9sBBHNPYnD7mjA6K_1qGEs9H8vVGNndHjZgQUNhYRsIFvx5Mml5EIDgI8QuH0nopOQLX4WNDTa_hHvm1aGkY4C6jjAsI$ <https://urldefense.com/v3/__https:/accreditationsupport.acr.org/support/solutions/articles/11000062800-phantom-testing-pet-revised-10-23-2025-__;!!KGKeukY!2B_SaoLiOmxgkrD2pZiXsX8iWJdmjJorE3R8OPYw-gqgZ8632rWlWt6zchEzI-9QoTyEOHVYxzeTCD0ZJAvwFzeuBp3uUNANbdIgtmr4ayGW$>, you are instructed to take your background SUV mean value from the “best 1 cm central slice (around the mid-point of the vials) of the hot cylinders…”.

But in the SUV Accuracy test as outlined in the QC manual (starting on page 45), you are told to average three background values from three consecutive slices in the uniform section of the phantom. And this picture accompanies those instructions:

[cid:image005.png at 01DC974F.A79BD310]

I get the argument that the QC manual is for routine testing (acceptance, annual, etc.), while the webpage is showing what’s needed for ACR submissions, but isn’t it odd that we would evaluate the same parameter (background mean SUV) differently depending on whether it’s an ACR survey versus annual?

There’s also this text on page 47 of the manual: “For the purpose of accreditation submission, the ACR defines the acceptable background SUVmean range in the Program Requirements but for the purpose of the physicist’s annual performance evaluation, background SUVmean should be between 0.95 and 1.05 (i.e. +/- 5%).” Is this an acknowledgment of the discrepancy?

What do others think?

Dylan DeAngelis, MS, DABR
NYS Licensed Medical Physicist
(Diagnostic Radiological Physics and Medical Nuclear Physics)

Upstate Medical Physics – Diagnostic Radiology, Medical Nuclear & Medical Health Physics, P.C.
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