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Computed tomography (CT) is an imaging modality that exposes patients to ionizing radiation (IR). We review and report findings from our pilot study evaluating whether blood markers are altered in 17 children undergoing medically indicated CT scans. Blood was drawn before ('pre-CT') and 1 hour after ('post-CT') CT scans. Plasma carotenoids, tocopherols, Q10, ascorbic acid (AA) and uric acid (UA) were analyzed by RP-HPLC with diode-array and electrochemical detection. Dehydroascorbic acid (DHAA) was calculated by subtraction from total AA. Total antioxidant capacity (TAC) was measured using the ORAC assay. Cytokines were quantified using a multiplex immunoassay. g-H2AX foci were visualized using immunofluorescence. Mean pre- and post-CT changes were compared using t-tests; P-levels < .05 indicated significance. All major plasma lipid soluble antioxidant levels were lower post- vs pre-CT (P < .05) possibly from the scavenging of free radicals formed by CT-induced IR. Average AA levels increased (134%) while DHAA levels were decreased (29%) post-CT, probably due to intracellular recycling of AA from DHAA. TAC levels in lipophilic and hydrophilic extracts were unchanged, suggesting that other antioxidants may have assisted in free radical quenching, which would corroborate their lower concentrations post-CT. Cytokine levels were unchanged and dose-dependent increases in γ-H2AX foci, a measure of double strand DNA breaks, were observed (P = .046, n = 3 children). Our results suggest that CT-derived IR can influence the antioxidant system and may elicit detrimental responses on the cellular level of young children. When possible and if appropriate non-IR based techniques such as ultrasound or magnetic resonance imaging should be used. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) exposes patients to ionizing X-irradiation (IR) that can alter the expression of genes responsible for controlling complex regulatory pathways. We sought to determine trends in the expression of 24 documented radiation-responsive genes linked to cancer in vivo. A total of 17 children (0.25-6 years old) undergoing medically indicated CT examinations with radiation doses ranging from 92.46 to 525.55 mGy cm (equivalent to effective doses of 0.78-11.30 mSv) were enrolled. Blood was drawn immediately before and 1 hour after their CT exams and mixed with an RNA additive for stabilization of gene expression. RNA samples of 14 of the 17 children were analyzed on a gene expression microarray. Absolute changes in gene expression were subtle, averaging less than 10%, but trends in expression changes of several genes were observed. ERP29, an endoplasmic reticulum chaperone, thought to be involved in the folding of secretory proteins, showed significant change in expression (8% decrease, P = 0.002) in the expected direction consistent with previous literature. PCNA expression increased linearly with CT dose (mGy cm) (P = 0.001). TP53 and FLT3LG expression increased linearly with effective dose (mSv) (P = 0.02 and P = 0.02). Previous IR exposure was associated with decreased GADD45A (P = 0.001) and FLT3LG (P = 0.03) and increased MDM2 expression (P = 0.02). We observed in this pilot study modest gene expression changes in the 24 IR-responsive candidate genes studied. Our results showed trends in gene expression changes, and they need to be confirmed in future studies with larger sample sizes to help develop risk assessments and preventive modalities for young patients undergoing CT. [ABSTRACT FROM AUTHOR]

Highlights: [•] Low dose X-irradiation from computer tomography alters plasma antioxidants in vivo. [•] Strongest predictors for post-CT plasma micronutrient changes were baseline levels. [•] Plasma antioxidants may protect against damage from X-rays during clinical CT scans. [ABSTRACT FROM AUTHOR]