Ionizing Radiation Exposure in Adults with Inflammatory Bowel Disease

From The Onion:

In the largest reported cohort to date, GC Nguyen et al (Inflamm Bowel Dis 2020; 26: 898-906) describe the ionization radiation exposure (IRE) in individuals (≥18 years) with inflammatory bowel disease (IBD).

Methods: N=72,933 with IBD,1994-2016. During 1st 5 yrs after diagnosis, IRE was estimated in a retrospective matched cohort in Ontario.

Key findings:

  • IBD patients were exposed to nearly 6-fold IRE due to abdominal imaging compared to controls: 18.6 mSv vs 2.9 mSv
  • Patients with CD had higher IRE than UC: 26 mSv vs 12 mSv (P<0.001).  CD patients were more likely to have >50 mSv exposure (15.6% vs 6.2%) and >100 mSv 5.0% vs 2.1%
  • Women were less likely to have high IRE compared to males
  • Residents in the poorest neighborhoods were 27% more likely to have IRE >100 mSv.  Socioeconomic status was an independent factor after accounting for comorbidities. The authors speculate that this could be related to increased use of emergency rooms where they may be more likely to receive a CT.
  • The use of CT scan began to decline after 2007…likely explained by the rise of MRE studies.

While strict guidelines on IRE are lacking, the International Commission on Radiological Protection has suggested that occupational exposure (eg. nuclear workers) should be limited to <100 mSv over 5 years and not more than 50 mSv in a single year.

My take: We need to continue efforts to reduce IRE due to concerns about subsequent secondary malignancies. This likely means avoiding CT for non-emergencies and working with our ED colleagues to think carefully about lifetime IRE in IBD patients.

Related blog posts:

Additional references:

  • -AJR 2001; 176: 289-96. Estimated risks of radiation-induced fatal cancer from pediatric CT
  • -Br J Radiol 2012; 85: 523-28.  Justification of CTs -some not needed
  • -AJR 2010; 194: 868-73.  Lower CT radiation doses in pediatric patients.  ‘Image gently’
  • -Arch Intern Med 2009; 169: 2078-86.

From LA Times: