Tin prefiltration in computed tomography does not significantly alter radiation-induced gene expression and DNA double-strand break formation

by Simone Schüle, Carsten Hackenbroch, Meinrad Beer, Patrick Ostheim, Cornelius Hermann, Razan Muhtadi, Samantha Stewart, Matthias Port, Harry Scherthan, Michael Abend

The tin (Sn) prefilter technique is a recently introduced dose-saving technique in computed tomography (CT). This study investigates whether there is an altered molecular biological response in blood cells using the tin prefiltering technique.

Blood from 6 donors was X-irradiated ex-vivo with 20 mGy full dose (FD) protocols (Sn 150 kV, 150 kV, and 120 kV) and a tin prefiltered 16.5 mGy low dose (LD) protocol on a CT scanner. Biological changes were determined by quantification of γH2AX DNA double-strand break (DSB) foci, and differential gene expression (DGE) relative to unexposed samples were examined for seven known radiation-induced genes (FDXR, DDB2, BAX, CDKN1A, AEN, EDA2R, APOBEC3H) and 667 microRNAs (miRNA).

EDA2R and DDB2 gene expression (GE) increased 1.7-6-fold (p = 0.0004–0.02) and average DNA DSB foci value (0.31±0.02, p<0.0001) increased significantly relative to unexposed samples, but similarly for the applied radiation protocols. FDXR upregulation (2.2-fold) was significant for FD protocols (p = 0.01–0.02) relative to unexposed samples. miRNA GE changes were not significant (p = 0.15–1.00) and DGE were similar for the examined protocols (p = 0.10–1.00). An increased frequency of lower DGE values was seen in the Sn 150 kV LD protocol compared to the 120 kV FD and Sn 150 kV FD protocols (p = 0.001–0.008).

The current ex-vivo study indicates no changes regarding transcriptional and post-transcriptional DGE and DNA DSB induction when using the tin prefilter technique and even a significant tendency to lower radiation-induced DGE-changes due to the dose reduction of the tin prefilter with equal image quality compared to classical CT scan protocols was found.