The Department of Homeland Security, specifically the Transportation Security Administration (TSA), intends to modify an existing contract with Smiths Detection Incorporated for Advanced Technology / Computed Tomography (AT/CT) systems. This modification aims to provide additional maintenance support services for the AT/CT systems that have been manufactured and deployed. These systems play a critical role in enhancing security measures within transportation sectors. Interested parties may express their interest and capability to respond to this requirement, although the government will negotiate with only one source under FAR 6.302. For further inquiries, interested vendors can contact Aubrey Gainfort at aubrey.gainfort@tsa.dhs.gov or Garon McCarty at garon.mccarty@tsa.dhs.gov.