[Intl_DxMedPhys] ACR NM Image Acquisition - Discrepancy

[Gretchen Raterman Bell]

Thank you for the explanation, Mike.  Official nonuniformity numbers for
"peak performance" should be done with 17-30 million.  The nonuniformity
numbers will be better (or the same if there truly is a problem) when going
from 10 to 30 million count statistics.  I would surmise that if you get
acceptable numbers with 10 million, then the 30 million count flood may not
be necessary.  However, from your experience, has there ever been an
artifact that was seen at 30 million counts that would be possibly covered
up by the noise in a 10 million flood?  I ask because we have run higher
counts as a sanity check when we have gotten poor numbers, and the number
typically stays the same.

Gretchen R. Bell, M.S., DABR
Diagnostic Imaging Physicist
Ochsner Medical Center
(504)842-8506



On Wed, Nov 5, 2025 at 2:16 PM Mike Nimmo <mike.t.nimmo at gmail.com> wrote:

> Hi Gretchen
>
> I think the disparity is between acr flood images for submission and
> annual QC. TG177 lists a table of count statistics outlining why at least
> 17 million counts should be acquired for annual testing, but it recommends
> 30 million.
>
> Honestly I've always wondered why the ACR is so low. I always do at least
> 17 million counts for my annual testing.
>
> Mike Nimmo
>
> On Wed, Nov 5, 2025, 2:06 PM Gretchen Raterman Bell via
> Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
> wrote:
>
>> Hey everyone, My team and I noticed a discrepancy between the ACR NM QC
>> manual and the "Phantom Testing" guidance page on their website: We've of
>> course always done 10 million (and previously 5 million).   Is this a typo
>> in the
>> Hey everyone,
>>
>> My team and I noticed a discrepancy between the ACR NM QC manual and the
>> "Phantom Testing" guidance page on their website:
>>
>> [image: image.png]
>>
>> [image: image.png]
>>
>> We've of course always done 10 million (and previously 5 million).  Is
>> this a typo in the ACR NM QC Manual?
>>
>> Gretchen R. Bell, M.S., DABR
>> Diagnostic Imaging Physicist
>> Ochsner Medical Center
>> (504)842-8506
>>
>>
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