title: Reduction in radiation doses from paediatric CT scans in Great Britain.
abstract: OBJECTIVE
  Although CT scans provide great medical benefits, concerns have been raised about the magnitude of possible associated cancer risk, particularly in children who are more sensitive to radiation than adults. Unnecessary high doses during CT examinations can also be delivered to children, if the scan parameters are not adjusted for patient age and size. We conducted the first survey to directly assess the trends in CT scan parameters and doses for paediatric CT scans performed in Great Britain between 1978 and 2008.
  
  
  METHODS
  We retrieved 1073 CT film sets from 36 hospitals. The patients were 0-19 years old, and CT scans were conducted between 1978 and 2008. We extracted scan parameters from each film including tube current-time product [milliampere seconds (mAs)], tube potential [peak kilovoltage (kVp)] and manufacturer and model of the CT scanner. We estimated the mean mAs for head and trunk (chest and abdomen/pelvis) scans, according to patient age (0-4, 5-9, 10-14 and 15-19 years) and scan year (<1990, 1990-1994, 1995-1999 and ≥2000), and then derived the volumetric CT dose index and estimated organ doses.
  
  
  RESULTS
  For head CT scans, mean mAs decreased by about 47% on average from before 1990 to after 2000, with the decrease starting around 1990. The mean mAs for head CTs did not vary with age before 1990, whereas slightly lower mAs values were used for younger patients after 1990. Similar declines in mAs were observed for trunk CTs: a 46% decline on an average from before 1990 to after 2000. Although mean mAs for trunk CTs did not vary with age before 1990, the value varied markedly by age, from 63 mAs for age 0-4 years compared with 315 mAs for those aged >15 years after 2000. No material changes in kVp were found. Estimated brain-absorbed dose from head CT scans decreased from 62 mGy before 1990 to approximately 30 mGy after 2000. For chest CT scans, the lung dose to children aged 0-4 years decreased from 28 mGy before 1990 to 4 mGy after 2000.
  
  
  CONCLUSIONS
  We found that mAs for head and trunk CTs was approximately halved starting around 1990, and age-specific mAs was generally used for paediatric scans after this date. These changes will have substantially reduced the radiation exposure to children from CT scans in Great Britain.
  
  
  CONCLUSIONS
  The study shows that mAs and major organ doses for paediatric CT scans in Great Britain began to decrease around 1990.
authors: 1 Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health Bethesda, MD, USA.
authors: Choonsik
authors: C
authors: Lee
authors: 2 Institute of Health and Society, Newcastle University, Sir James Spence Institute, Royal Victoria Infirmary, Newcastle upon Tyne, UK.
authors: Mark S
authors: MS
authors: Pearce
authors: 2 Institute of Health and Society, Newcastle University, Sir James Spence Institute, Royal Victoria Infirmary, Newcastle upon Tyne, UK.
authors: Jane A
authors: JA
authors: Salotti
authors: 2 Institute of Health and Society, Newcastle University, Sir James Spence Institute, Royal Victoria Infirmary, Newcastle upon Tyne, UK.
authors: Richard W
authors: RW
authors: Harbron
authors: 1 Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health Bethesda, MD, USA.
authors: Mark P
authors: MP
authors: Little
authors: 3 Great Ormond Street Hospital for Children NHS Trust, London, UK.
authors: Kieran
authors: K
authors: McHugh
authors: 4 The Newcastle upon Tyne, Hospitals, NHS Foundation Trust, Newcastle upon Tyne, UK.
authors: Claire-Louise
authors: CL
authors: Chapple
authors: 1 Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health Bethesda, MD, USA.
authors: Amy
authors: A
authors: Berrington de Gonzalez
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006257:Head / Q000528:radiation effects; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011829:Radiation Dosage; D000069079:Radiation Exposure / Q000517:prevention & control*; D011874:Radiometry; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data; D060726:Torso / Q000528:radiation effects; D006113:United Kingdom; D055815:Young Adult