Should radiologists care about kV? Phantom and clinical study of effects of kV on hemoperitoneum HU in the setting of splenic injuries
Evaluate the potential effects of X-ray tube voltage (kV) changes on Hounsfield unit (HU) measurements of hemoperitoneum in patients with blunt splenic injuries.
Eight different tissue equivalent electron density plugs in the Electron Density Phantom were scanned (muscle, adipose, breast, liver, lung (exhale), lung (inhale), trabecular bone, and dense bone). The phantom was scanned at different kV values (70, 80, 100, 120, and 140 kV). In the clinical study, the local trauma registry database was queried for splenic injuries between January 2015 and December 2016 with a final cohort of 110 patients. The average HU numbers of hemoperitoneum found in three different anatomic locations (pelvic, perisplenic, and perihepatic) were compared at different kV values (100 kV, 120 kV, and 140 kV). ANOVA and pairwise t tests were performed for statistical analysis.
In both studies, HU measurements generally decreased as kV increased, and vice versa. One hundred ten patients were reviewed: 29 for 100 kV, 66 for 120 kV, and 15 for 140 kV. For the perihepatic group, significant differences were observed in average HU in the following pairwise comparisons: 100/140 (13.7 (5.3), p < 0.05) and 120/140 (10.3 (4.5), p < 0.05). For the perisplenic group, significant differences were observed in 100/120 (7.0 (3.5), p < 0.05) and 100/140 (13.2 (4.9), p < 0.05). No significant difference was observed in the pelvic location (p = 0.5594).
HU measurements of hemoperitoneum in patients with blunt splenic injuries significantly varied with the use of different kV values. Radiologists should be aware of the possible effects of altering kV on HU.
KeywordsCARE kV Computed tomography Automated dose-optimized tube voltage selection Hemoperitoneum Hounsfield unit Tube voltage
The project described was partially supported by the National Center for Advancing Translational Sciences, UL1TR000117, and the Dean of the College of Medicine, University of Kentucky.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or the University of Kentucky.
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