Low-to-moderate dose ionizing radiation and cerebrovascular disease mortality in U.S. radiologic technologists, 1983-2021

  1. Mark P. Little
  2. Martha S. Linet
  3. Isabelle F. van der Velpen
  4. Taeeun Kwon
  5. Hae Gin Han
  6. Choonsik Lee
  7. Elizabeth K. Cahoon
  8. Jim Z. Mai
  9. Jeremy S. Miller
  10. Bruce H. Alexander
  11. Cari M. Kitahara
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Abstract

Background

Substantial data confirm the association of cerebrovascular disease (CeVD) with high-dose (>1 Gy) ionizing radiation exposures, but less is known about risks at low- to moderate doses (<1 Gy). A few studies have reported increased CeVD risks at doses <500 mGy, but none of these provided data on CeVD risks by subtype. Few studies have investigated the potential modifying effects of age, sex, and other major CeVD risk factors.

Methods

110,368 radiologic technologists certified for ≥2 years during 1926-1982 with at least one baseline survey response (1983-1998) were followed-up through December 2021. Linear proportional hazards regression analysis was performed of cumulative occupational radiation exposure and CeVD mortality risks, using estimated thyroid-absorbed dose as a proxy for carotid artery dose, in addition to brain and badge dose.

Results

During a median 35.1 (maximum 38.9) years of follow-up, 1,199 deaths from CeVD (634 ischemic stroke, 369 hemorrhagic stroke, 196 other types) were identified. Cumulative thyroid dose (mean/maximum=68.4/2784 mGy) was positively associated with deaths from overall CeVD (excess hazard ratio [EHR]/100 mGy=0.07 95% CI 0.01, 0.16, p =0.01) and ischemic stroke (EHR/100 mGy=0.10, 95% CI 0.02, 0.23, p =0.01), while no clear associations were observed for hemorrhagic stroke (EHR/100 mGy=0.04, 95% CI −0.04, 0.23 p =0.43) or other CeVD (EHR/100 mGy=0.02, 95% CI −0.10, 0.29, p =0.81). Trends were similar for total CeVD using badge dose (EHR/100 mSv=0.08, 95% CI 0.02, 0.16, p <0.01), but larger with brain dose (EHR/100 mGy=0.34, 95% CI −0.00, 0.81, p =0.05). Body mass index modified the CeVD dose-response ( p =0.04), but year of birth, time since exposure, age at exposure, attained age, sex, smoking, and alcohol consumption did not modify the CeVD dose-response (all p >0.05), nor did adjusting for history of diabetes, hypertension or high cholesterol. Trends remained significant when restricting thyroid doses to <1,000 mGy (EHR/100 mGy=0.06, 95% CI −0.00, 0.16, 1-sided p =0.03).

Conclusions

In the first cohort study to assess low-to-moderate occupational ionizing radiation dose in medical workers with CeVD mortality risk by subtype, greater occupational ionizing radiation exposure was associated with increased mortality risk from total CeVD and ischemic stroke, independent of demographic and lifestyle-related factors and comorbid conditions.

Clinical Perspective

  • For the first time we have documented radiation-related excess cerebrovascular disease risk, specifically of ischemic type, in a group of US radiologic technologists at relatively modest levels of dose (<1000 mGy).

  • Unique among occupational cohorts there is rich data on lifestyle and other risk factors (including smoking, alcohol consumption, body mass index, diabetes, elevated serum cholesterol, or hypertension) in this group, few of which materially modify the radiation dose response.

  • These results reinforce the need for radiation protection practices aimed at keeping exposures to medical staff and patients as low as reasonably achievable.

Article activity feed

  1. Version published to 10.64898/2026.10.21.26366178 on medRxiv