National and local diagnostic reference levels for adult ¹⁸F-FDG and CT in Jordanian PET/CT: findings and implications in practice

Abstract

Purpose: This study aims to report the findings of Jordanian national diagnostic reference level (NDRL) survey for fluorodeoxyglucose (18F-FDG) and local diagnostic reference level (LDRL) of computed tomography (CT) used for attenuation correction and anatomical localization (AC-AL); and attenuation correction and diagnostic CT (AC-DX) within the context of whole-body WB and half-body HB adult oncology PET/CT scanning.
Methods: Two-structured questionnaires were prepared to gather the necessary information: dosimetry data, patient demographics, equipment specification, and acquisition protocols for identified 18F-FDG PET/CT procedures. The NDRL and achievable dose were reported based on the 75th and 50th percentiles for 18F-FDG administered activity (AA), respectively. The LDRL was reported based on the 50th percentile for (CTDIvol) and (DLP). 
Results: Data from 562 patients from four Jordanian PET/CT centres were collected. The survey revealed that Jordanian NDRL for administered activity (AA) (303 MBq) was within the acceptable range compared to the published-peer NDRL data (240 to 590 MBq). However, the 18F-FDG AA varied across the participated PET/CT centres. The reported LDRL CTDIvol and DLP of CT used for (AC-AL) was 4.3 mGy and 459.3 mGy.cm for HB CT scan range, and 4.1 mGy and 659.9 mGy.cm for WB CT scans. The reported LDRL for CTDIvol and DLP for HB CT was higher when compared with the United Kingdom (3.2 mGy and 310 mGy.cm). Concurrently, in the context of WB CT, the reported values (i.e., CTDIvol and DLP) were also higher than both Kuwait (3.6 mGy and 659 mGy.cm) and Slovenia (3.6 mGy and 676 mGy.cm). The reported HB CT(AC-DX) was higher than Nordic, New Zealand and Swiss NDRLs and for WB (AC-DX) CT it was higher than Swiss NDRLs
Conclusion: This study reported the first Jordanian NDRL for 18F-FDG and LDRL for HB and WB CT associated with 18F-FDG PET/CT scans. This data is useful for Jordanian PET/CT centres to compare their LDRL to the suggested DRLs and utilize it in the process of optimising CT radiation doses.