Cumulative Radiation Exposure Post Aneurysmal Subarachnoid Haemorrhage.

Abstract

Background: Patients with aneurysmal subarachnoid haemorrhage (aSAH) often receive multiple radiation based diagnostic studies. Cumulative radiation exposure has been associated with long term health consequences from both dose dependent deterministic harm and increased risk of developing adverse events in a non-dose dependant manner i.e. stochastic harm.

Objective: The objective was to calculate cumulative radiation exposure in the acute phase after aSAH.

Design, setting, participants, main outcome measures: Single centre retrospective, observational study of consecutive adult patients admitted to the ICU for management of aSAH over five years. Organ and effective radiation doses were determined using institution specific conversion coefficients based on scanner radiation output metrics for all computed tomography imaging and fluoroscopy examinations. Calculated patient doses for the duration of the hospital admission were determined using National Cancer Institute radiation dosimetry tools.

Results: A total of 276 patients met the inclusion criteria; 180 females (65%), mean (SD) age 56 (13) years. There were 222 (80%) patients who survived to hospital discharge. The median [IQR] effective cumulative radiation dose was 17.7 [9.7-30.5] mSv. Twenty-one patients (8%) received an effective dose > 50 mSV consistent with potentially harmful ionising radiation exposure. In 162 patients (59%), the equivalent radiation dose to the lens of the eye exceeded the 500 mSv threshold for radiation induced damage.

Conclusion: Survivors of aSAH are exposed to high levels of medical radiation. The eyes are particularly at risk with most patients exposed to levels known to induce lens damage. This highlights the importance of strategies to reduce incidental and cumulative medical radiation exposure in this population.