[Intl_DxMedPhys] Higher doses (CTDIvol) for Prospective Cardiac scans on Siemens Force CT

[Troy Zhou]

Cardiac CT dose is determined by heart rate more than body habitus. The adaptive cardio sequence mode has flex padding which will open up the 100% dose region of heart rate varies quickly from one heart beat to another.

Troy 


> On Mar 19, 2025, at 3:25 PM, Yue Zhang via Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list at lists.osu.edu> wrote:
> 
> 
> Hi List,
> 
> We are experiencing higher doses (CTDIvol) for Prospective Cardiac scans on Siemens Force CT. I am trying to figure out the reason.
> 
> This was a prospective cardiac acquisition (DS_Cor Seq) that exceeded the 60 mGy limit, reaching 121.49 mGy. Our prospective cardiac scan is done in the sequential mode. CarekV is on. The DICOM tag for pitch, (0018, 9311) is 0.  Patient Weight = 227 lb. The patient was not very big, from our point of view.
> 
> Unfortunately no ECG on PACS, I can't see the exact heart beat pattern. But from PACS, Cardiac Series showed 63, 59, 57, 60 bpm, and 1935 mA constantly. From the scout, the heart position is a little higher on the table. What do you think?  
> 
> Why did the scanner choose to use such high mA? The only things I can think of that might trick the AEC in a wrong way, are the wires on the patient, or the jewelry or metals on the side of cheek (red arrows in the 3rd pic). But, can those little things trigger the AEC to choose such high mA during the acquisition?
> 
> <Radimetrics Screenshot.jpg>
> 
> 
> <PACS Patient Protocol Screenshot.jpg>
> 
> 
> <Scout AP.JPG>
> 
> 
> <Scout Lateral.JPG>
> 
> 
> <Cardiac image screenshot.JPG>
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> 
> <20250319_134417 v2.jpg>
> 
> In the above picture, the cardiac CARE Dose curve was changed in June 2023 from the default average to the current ones. Because the radiologists complained about image quality. We don't know how Siemens defines Adult slim or obese. 
> 
> My question is, what could be the reason to cause such a high dose in prospective cardiac scans? Thank you very much. 
> 
> --
> Yue
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