[Intl_DxMedPhys] Siemens PET/CT shielding?

Fri May 30 22:15:40 EDT 2025

I agree – radiation due to patients being incubated in the vicinity of the scanner won’t be a PET image quality concern.

(Nice analysis BTW Tim – not bad for a CT physicist!)

Matt Palmer

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces at lists.osu.edu> On Behalf Of Szczykutowicz, Timothy P via Intl_dxmedphys_wd_osu_list
Sent: Friday, May 30, 2025 12:40 PM
To: Ryan Fisher <rfisher1 at metrohealth.org>; intl_dxmedphys_wd_osu_list at lists.osu.edu
Subject: [External] Re: [Intl_DxMedPhys] Siemens PET/CT shielding?

I think the primary and scatter rates from the patient in the scanner with anatomy outside the region of interest would be way higher than scatter and primary from patients in the uptake room (like exponentially higher due to 1 over r squared
I think the primary and scatter rates from the patient in the scanner with anatomy outside the region of interest would be way higher than scatter and primary from patients in the uptake room (like exponentially higher due to 1 over r squared and room shielding). The scanner will already be designed to deal with this (i.e., you are doing a whole body PETCT and you need X table positions, whenever the patient is in a table position not being scanned actively, those parts of the patient are still radioactive and way closer and not shielded to the scanner). The scanner will have internal shielding and detectors designed to minimize the impact of these out of scan FOV photons, and I would assume the line of response algos and similar software would deal with these pretty easily.

But I do CT and try to stay away from radioactive liquids as much as possible 😉 so take my answer with a grain of NaCl.

-stick

Timothy P. Szczykutowicz, Ph.D., DABR
Associate Professor
Departments of Radiology, Medical Physics and BME
University of Wisconsin Madison
Cell# 1-716-560-7751<tel:(716)%20560-7751>
Office# 1-608-263-5729
he/him/his

From: Intl_dxmedphys_wd_osu_list <intl_dxmedphys_wd_osu_list-bounces+tszczykutowicz=uwhealth.org at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list-bounces+tszczykutowicz=uwhealth.org at lists.osu.edu>> On Behalf Of Ryan Fisher via Intl_dxmedphys_wd_osu_list
Sent: Friday, May 30, 2025 11:21 AM
To: intl_dxmedphys_wd_osu_list at lists.osu.edu<mailto:intl_dxmedphys_wd_osu_list at lists.osu.edu>
Subject: [Intl_DxMedPhys] Siemens PET/CT shielding?

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Hello! We’re in the process of building out a new PET/CT suite, which is going to include multiple uptake rooms immediately adjacent to the scanner room, with an existing CT on the other side of the uptake rooms. Blueprint snip below, and it’s
Hello!

We’re in the process of building out a new PET/CT suite, which is going to include multiple uptake rooms immediately adjacent to the scanner room, with an existing CT on the other side of the uptake rooms. Blueprint snip below, and it’s a Siemens Trinion PET/CT with a Force in the other room, FWIW. I reached out to Siemens to see if they had any specs as far as ambient exposure rates to either scanner to prevent image quality issues and just got a generic:
[cid:image001.png at 01DBD1B0.5F313030]
which is not super helpful as the site’s Radiation Safety Officer.

I’m wondering if anyone has experience with shielding this kind of layout? Siemens is the one who provided the basic room layout, so presumably they’ve installed something similar before without issues and shielding to occupational limits in the area is sufficient to prevent any artifacts? I guess I’m just surprised they don’t have any kind of “exposure rate > XX will affect camera performance” specification and am a little nervous of finding that out the hard way after everything is built and installed.

Thanks!
Ryan

[cid:image002.png at 01DBD1B0.5F313030]

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