What is the estimated radiation exposure for a patient undergoing a 30-minute stroke thrombectomy procedure using a biplane angiography machine?

Radiation Exposure During 30-Minute Stroke Thrombectomy with Biplane Angiography

For a 30-minute stroke thrombectomy using biplane angiography, you can expect a patient radiation exposure of approximately 91-148 Gy·cm² (dose-area product/KAP), which translates to an effective dose of roughly 18-30 mSv—equivalent to 6-10 years of natural background radiation. 1

Patient Radiation Dose Estimates

The most robust contemporary data comes from a 2019 multicenter study of 1,096 thrombectomy patients, which established the 75th percentile achievable level at 148 Gy·cm² for biplane systems with radiation dose-reduction systems (RDS). 1 This represents the benchmark for modern practice.

Dose Ranges by Equipment Type

• Biplane systems with RDS: Median DAP of 91 Gy·cm² (air kerma 0.46 Gy), with 75th percentile at 148 Gy·cm² and 0.73 Gy respectively 1
• Biplane systems without RDS: Median DAP of 140 Gy·cm² (air kerma 0.97 Gy)—representing 35% higher DAP and 53% higher air kerma compared to RDS-equipped systems 1
• Skin equivalent dose range: 0.16-4.80 Gy, with mean of 1.00 Gy and 75th percentile of 1.24 Gy 2

Converting to Effective Dose

Using the ACC/AHA conversion factor of 0.20 mSv per Gy·cm² for thoracic/head imaging, a typical 30-minute thrombectomy delivers: 3

• With RDS: 91 Gy·cm² = approximately 18 mSv effective dose
• Without RDS: 140 Gy·cm² = approximately 28 mSv effective dose
• Upper achievable limit: 148 Gy·cm² = approximately 30 mSv effective dose

Clinical Context and Risk Assessment

These doses fall well below the 100 mSv threshold where detectable increased cancer risk begins, according to ACC guidelines. 3, 4 To contextualize:

• Natural background radiation in the US averages 3 mSv per year 3, 4
• A typical thrombectomy (18-30 mSv) equals 6-10 years of background radiation
• This is comparable to 2-3 cardiac CT scans (10-21 mSv each) 4
• Standard diagnostic coronary angiography delivers 5-6 mSv 4

Deterministic Skin Injury Risk

The threshold for skin reactions is 3 Gy absorbed dose, which was exceeded in only 6% of thrombectomy cases in a 50-patient German study. 2 However, 36% of patients received 1-3 Gy, approaching concerning levels. 2

ACC/AHA guidelines recommend warning patients and arranging follow-up at 1 and 3 months post-procedure if fluoroscopy time exceeds 50 minutes on modern equipment or 30 minutes on older systems (>5 years), or if dose exceeds 4 Gy at the interventional reference point. 3

Factors Affecting Dose Variability

Radiation exposure varies considerably based on:

• Occlusion location: Posterior circulation and carotid occlusions produce highest doses 2
• Fluoroscopy time: Range of 5.7-137.3 minutes (mean 39.5 minutes) in clinical practice 2
• Equipment age and technology: RDS reduces exposure by 35-53% 1
• Patient characteristics: Obesity increases dose requirements 3
• Operator technique: Beam collimation, positioning, and minimizing beam-on time are critical 3

Operator Exposure

For the interventionalist, typical operator exposure is approximately 0.1 mSv per Gy·cm² of patient KAP, meaning a 100 Gy·cm² thrombectomy delivers roughly 10 mSv to the operator—about 1/2,000th of patient exposure. 3 An active neurointerventionalist performing 500 procedures annually may receive up to 10 mSv/year occupational dose. 3

Critical Dose Reduction Strategies

The ACC/AHA emphasizes three fundamental ALARA principles: 3

1. Minimize beam-on time: Use fluoroscopy only when actively viewing; utilize last-image-hold feature 3
2. Optimize beam collimation: Actively collimate to minimum necessary field size 3
3. Optimize geometry: Minimize patient-to-detector distance; maximize source-to-patient distance 3

Modern biplane systems with radiation dose-reduction technology should be considered standard of care, as they reduce exposure by one-third to one-half without compromising procedural success or safety. 1