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Assessment of Exam-Specific Target Exposure Indices (TEI) as a Function of a Reference Exposure Index (EI) for Agfa Computed Radiography (CR) and Digital Radiography (DR)

K Hulme1*, R Fisher1 , K Scilla2 , (1) The Cleveland Clinic, Beachwood, OH, (2) Cleveland State University, Cleveland, Ohio


(Monday, 7/30/2018) 1:15 PM - 1:45 PM

Room: Exhibit Hall | Forum 1

Purpose: The aim of this work was to investigate whether exam-specific TEIs created from clinical computed radiography (CR) dose statistics were appropriate for retrofit DR systems.

Methods: Prior to upgrading rooms to wireless DR panels (Agfa DR14s-CsI), exposure data was exported from 8 workstations at 5 sites utilizing CR (Agfa MD4.0 and HD5.0). 96,516 dose statistics were analyzed and exam groups were binned into TEI-subgroups based on average deviation index from a reference EI value (TEIᵣ). Each subgroup was assigned a linear scaling factor (K) which could be used to determine exam-specific TEIs from TEIᵣ (TEI=K·TEIᵣ). During the retrofit, AECs were calibrated and manual technique charts adjusted to account for the lower target dose of the DR panel (2.5 μGy) compared to CR (4.0 μGy), and calculated TEIs were scaled accordingly. DR exposure data was collected after 3 months, yielding 39,658 dose statistics which were analyzed in the same manner as the CR data. The resulting DR TEI-subgroups were compared to those derived from CR data.

Results: Analysis of CR data resulted in the creation of six TEI-subgroups; four for phototimed exams and two for manual/extremity exams. A preliminary review of DR data indicates that assigned TEI values are generally appropriate. It was determined that the number of TEI-subgroups could be reduced, as two previously distinct phototimed subgroups could be combined. Due to standardization of manual technique charts, TEI values for extremity exams could be lowered ~20%, and could possibly be collapsed into a single subgroup.

Conclusion: Exam-specific TEI values were originally configured for Agfa DR using 6 TEI-subgroups derived from CR data. Analysis of dose statistics acquired after DR retrofits resulted in a consolidated list of 5 TEI-subgroups. This methodology has proved useful for creating and refining vendor specific, exam-based, TEI values using clinical exposure data.


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