[Intl_DxMedPhys] Siemens CTDI Tool & Flash Protocol Questions

[Jim Tomlinson]

Make sure you use actual mAs and not effective mAs for dosimetry.

James A. Tomlinson, M.S., FACR

On Fri, Jan 31, 2025, 8:24 AM Dale Schippers via Intl_dxmedphys_wd_osu_list
<intl_dxmedphys_wd_osu_list at lists.osu.edu> wrote:

> For custom CTDI tool, you can set the DFOV in your helical protocol (e. g.
> , 35cm for body scans), before saving it as ctdi_body. Custom CTDI tool
> will convert the helical protocol to axial with the same DFOV (35cm) and
> mAs corrected for pitch.
> For custom CTDI tool, you can set the DFOV in your helical protocol (e.g.,
> 35cm for body scans), before saving it as ctdi_body. Custom CTDI tool will
> convert the helical protocol to axial with the same DFOV (35cm) and mAs
> corrected for pitch.
>
> With service window open (close CTDI measurement window), you can open the
> patient browser, look for service patient, and drag the series from Service
> patient to your ACR phantom patient-> ACR phantom study. You can also
> change the series description on Siemens Acquisition workstation, e.g.,
> from "rot" to "CTDI Adult Abd”. Patient: Service Patient, Study: Customer
> CTDI. To make it easier to drag images from the service patient into your
> ACR patient, you can Mark the 2 studies and Filter by Marked and then drag
> and drop.
>
> On Thu, Jan 30, 2025 at 11:06 PM Daniel Vergara via
> Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
> wrote:
>
>> Hi Gretchen, While using service tool, go to the patient browser and
>> search for service patient. The images are in there and an available only
>> while the tool is open. Siemens uses flying focal spot in these scanners,
>> probably the SOMATOM drive
>> Hi Gretchen,
>>
>> While using service tool, go to the patient browser and search for
>> service patient. The images are in there and an available only while the
>> tool is open.
>>
>> Siemens uses flying focal spot in these scanners, probably the SOMATOM
>> drive too. The beam width is actually half of the full coverage per
>> rotation under this mode. So make sure you take half of the displayed nT to
>> compute the CTDI100. If you already did that or this system doesn’t perform
>> flying focal spot, then another thing to consider is checking what your
>> meter’s delay time is set to. With a dual scan, it is possible that the
>> meter was delayed during the second scan and missed it. I had that
>> experience and changing the delay time on the meter (in my case Piranha) to
>> 100ms, it caught the two exposures but as two separate measurements.
>>
>> Thank you,
>> Daniel Vergara
>>
>> On Jan 30, 2025, at 1:07 PM, Gretchen Raterman Bell via
>> Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu>
>> wrote:
>>
>> 
>> Hi, group!  I had to type in a new name for the list! I was wondering if
>> anyone has successfully grabbed the images produced (or not produced?) when
>> using the CTDI Tool on Siemens.   My group covers a site that isn't ACR
>> accredited yet for
>> Hi, group!  I had to type in a new name for the list!
>>
>> I was wondering if anyone has successfully grabbed the images produced
>> (or not produced?) when using the CTDI Tool on Siemens.  My group covers a
>> site that isn't ACR accredited yet for pediatrics, but I believe they will
>> at some point.
>>
>> In addition, we have another site with a Somatom Drive (dual energy, two
>> tubes) that has the capability of acquiring with what's called Flash mode.
>> I believe the unit is using both tubes to be able to up the pitch, which is
>> 3 in some of the protocols developed at the site with apps.  When I used
>> the CTDI tool on their Flash Ped Abd protocol, the expected mA displayed in
>> QA->CTDITOOL program came in at about half of what I'd calculate using the
>> eff mAs, t/rot, pitch.  I'm assuming this is because there's two tubes??
>> Does anyone have any good reading material on how exactly these Flash
>> protocols work?  I'd like to understand it better.
>>
>> Thanks as always,n R. Bell, M.S., DABR
>> Diagnostic Imaging Physicist
>> Ochsner Medical Center
>> (504)842-8506
>>
>>
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