title: Dose-length product of scanners correlates with DNA damage in patients undergoing contrast CT.
abstract: OBJECTIVE
  Computed tomography (CT) exams contribute for a large part to the population's radiation burden. This study addresses the question if dose settings of scanners expressed by dose-length product (DLP) are correlated with directly measurable biological effects in patients.
  
  
  METHODS
  DLP, blood dose, effective dose and DNA damage were analyzed for patients undergoing a thoracic or abdominal contrast CT scan on two CT scanners with different dose settings. The DNA damage was assessed by scoring γ-H2AX foci representing DNA double-strand breaks (DSBs) in patient's lymphocytes. Blood dose was calculated using the ImPACT software.
  
  
  RESULTS
  The CT system operating at higher dose settings represented by higher DLP values, resulted in a significantly higher number of radiation-induced γ-H2AX foci in patient's lymphocytes (DLP: 2.1 times higher; γ-H2AX foci: 2.3 times higher; p<0.05). Plotting γ-H2AX foci versus blood dose showed a systematic increase of DNA damage with dose. In vitro experiments ruled out a possible X-ray enhancement of DNA damage effect by contrast agent.
  
  
  CONCLUSIONS
  Present study demonstrates that optimization of DLP setting of scanners results in a reduction of X-ray effects in patients.
authors: Department of Basic Medical Sciences, Ghent University, Proeftuinstraat 86, 9000 Gent, Belgium. Laurence.Beels@UGent.be
authors: Laurence
authors: L
authors: Beels
authors: Klaus
authors: K
authors: Bacher
authors: Peter
authors: P
authors: Smeets
authors: Koenraad
authors: K
authors: Verstraete
authors: Anne
authors: A
authors: Vral
authors: Hubert
authors: H
authors: Thierens