Patients undergoing recurrent CT scans: assessing the magnitude

Area of Science:

• Radiology and Medical Imaging
• Radiation Oncology
• Public Health

Background:

• Multiple computed tomography (CT) examinations can lead to significant cumulative effective dose (CED) in patients.
• Assessing the prevalence and demographic distribution of patients exceeding a 100 mSv CED is crucial for understanding radiation risk.
• Previous studies have not extensively detailed the age distribution of patients receiving high cumulative radiation doses from recurrent CT scans.

Purpose of the Study:

• To determine the percentage of patients undergoing multiple CT exams who reach a CED of ≥ 100 mSv.
• To analyze the age distribution of these patients, with a focus on those ≤ 50 years old.
• To identify the timeframe over which high CEDs are accrued.

Main Methods:

• Retrospective data analysis from radiation dose monitoring systems across four institutions (324 hospitals).
• Identification of patients with CED ≥ 100 mSv from recurrent CT exams within a 1-to-5-year period.
• Assessment of age and gender distribution for patients exceeding the CED threshold.

Main Results:

• Out of 2.5 million patients and 4.8 million CT exams, 1.33% (33,407) reached a CED ≥ 100 mSv.
• The median CED was 130.3 mSv, with a maximum of 1185 mSv.
• While most patients (72-86%) were > 50 years, 13.4% to 28% were ≤ 50 years. The minimum time to reach 100 mSv was as short as one day.

Conclusions:

• Patients receiving high cumulative radiation doses (≥ 100 mSv) from multiple CT scans within 1-5 years are increasingly common.
• A substantial fraction of these high-dose patients are younger than 50, raising concerns about potential long-term radiation effects.
• There is an urgent need for the development of CT scanners and protocols capable of delivering sub-mSv doses to mitigate risks associated with cumulative radiation exposure.