Diagnostic Reference Levels of CT Radiation Dose in Whole-Body PET/CT

Abstract

The role of CT in PET/CT imaging includes acquisition techniques for diagnostic, anatomic localization, and attenuation correction purposes. Diagnostic reference levels of the volumetric CT dose index (CTDI vol ) are available for dedicated CT procedures on selected body regions, but similar reference levels for whole-body CT used in PET/CT examinations are limited. This work reports CTDI vol values from sites that conduct whole-body oncologic PET/CT examinations and participated in the scanner validation program of the Society of Nuclear Medicine and Molecular Imaging Clinical Trials Network. Methods: From 2010 to 2014, a total of 154 sites submitted CT acquisition parameters used in their clinical 18 F-FDG PET/CT oncology protocols. From these parameters, the CTDI vol was estimated using the ImPACT CTDI dosimetry tables. Histograms of CTDI vol values were created for each year, and descriptive statistics, including mean, median, and 75th percentile, were reported. Repeated-measures ANOVA was performed to determine whether significant differences occurred between reporting years. Results: A wide range of technical parameters was reported, most notably in tube current. Between 2010 and 2014, the median CTDI vol ranged from 4.9 to 6.2 mGy and the 75th percentile from 9.7 to 10.2 mGy. There was no significant change in CTDI vol between reporting years (repeated-measures ANOVA, P 5 0.985). Conclusion: The 75th percentile CTDI vol reported in this work was 9.8 mGy averaged over all reporting years. These data provide a resource for establishing CTDI vol reference values specific to performing CT in PET/CT whole-body examinations. The wide ranges of CT acquisition parameters reported by sites suggest that CTDI vol reference levels may be beneficial for optimization of CT protocols.

CT protocol optimisation in PET/CT: a systematic review

“…This systematic review focused on the description of different applications of CT scans in PET/CT exams; it included 24 articles for a total of 2948 patients and two papers containing large multicentre studies for comparing the results [7,35] as shown in Fig. 1.…”

“…The first paper used for the comparison of our results was made by Fahey et al [7] and focused their work on the dosimetric aspects of paediatric PET/CT exams. The second work, conducted by Jallow et al [35], described diagnostic reference levels of CT scans in WB PET/CT studies. Fahey et al [7] argued that no consistent guidelines are available for CT acquisitions in PET/CT, especially when a paediatric PET/CT exam was involved; in addition to this, they discussed the variability of this study protocol using 19 North American paediatric institutions.…”

Effective dose estimation for oncological and neurological PET/CT procedures

“…CTDI vol 75 th percentile of whole-body oncological PET/CT protocols submitted to the Society of Nuclear Medicine and Molecular Imaging Clinical Trials Network ranged from 9.7 to 10.2 mGy [24]. The wide ranges of CT acquisition parameters suggested that CTDI vol reference levels may help to optimize CT protocols.…”

Diagnostic reference levels for 18F‐FDG whole body PET/CT procedures: Results from a survey of 12 centres in Australia and New Zealand

“…Published articles reported 18 F‐FDG PET/CT DRL values for the administered activity or CT used for AC and anatomical localization purposes, with few authors reporting both radiation doses . PET/CT DRLs from both radiation sources should be reported to provide suitable guidelines for professionals .…”

“…Clinical facilities with a median emergent dose that is higher than the national 75 th percentile dose should consider methods of optimizing their clinical imaging protocols to minimize the radiation doses delivered to the patients. 10 Published articles reported 18 F-FDG PET/CT DRL values for the administered activity [11][12][13][14][15][16][17][18][19] or CT 20,21 used for AC and anatomical localization purposes, with few authors reporting both radiation doses. 6,22 PET/CT DRLs from both radiation sources should be reported to provide suitable guidelines for professionals.…”