Investigation of Radiation Exposure of Patients with Acute Ischemic Stroke during Mechanical Thrombectomy.

PURPOSE

In radiological interventions, the skin is the most exposed organ. The aim of this study was to investigate the local dose exposure and the resulting risk of deterministic radiation effects for patients who underwent mechanichal thrombectomy.

MATERIALS AND METHODS

The examination protocols of 50 consecutive stroke patients who underwent mechanical thrombectomy from September 2016 to April 2017 were evaluated in this study. All procedures were performed on a biplanar angiographic suite. The local skin equivalent dose (0.07) was calculated retrospectively using the recorded radiation data and previously measured conversion factors. The in-vitro determination of the conversion factors was performed with a silicon semiconductor detector on the surface of an Alderson-Rando head phantom depending on the radiation quality.

RESULTS

Vessel occlusion was located in the M1 and M2 segments of the cerebral artery media (n = 32), the internal carotid artery or carotid-T (n = 12) and the basilar artery (n = 6). The fluoroscopy times ranged from 5.7 minutes to 137.3 minutes with an average value of 39.5 ± 4.1 minutes. The determined skin equivalent dose values ranged from 0.16 ± 0.02 Gy to 4.80 ± 0.51 Gy, with the mean value being 1.00 ± 0.14 Gy. In 3 out of 50 cases (6 %), the threshold value for skin reactions of 3 Gy published by the German Radiation Protection Commission was exceeded. A further 15 patients (36 %) were exposed to a dose of 1-3 Gy. The highest dose values were achieved during long procedures with occlusions in the posterior circulation and carotid occlusions. In addition, a local dose reference level of 1.24 ± 0.15 Gy could be determined for the skin equivalent dose in mechanical thrombectomies for our center.

CONCLUSION

Even during a modern neuroradiological intervention, such as mechanical thrombectomy, radiation doses to the patient are produced and can lead to deterministic radiation damage to the skin in approximately 6 % of cases. Systematic monitoring of local dose quantities, such as (0.07), seems appropriate. Possibilities for recording and reducing the local dose load should be developed by the interventional teams in cooperation with a medical physics expert.

KEY POINTS

· In 64 % of the thrombectomies the skin equivalent doses were in the harmless range (< 1 Gy).. · In 6 % of the patients higher H P(0.07) values were determined, which can lead to deterministic radiation damage to the skin.. · To avoid deterministic damage during neurointerventions, H P(0.07) should be recorded (combined measuring chambers).. · For longer interventions, precautions should be taken to reduce the radiation dose..

CITATION FORMAT

· Bärenfänger F, Block A, Rohde S. Investigation of Radiation Exposure of Patients with Acute Ischemic Stroke during Mechanical Thrombectomy. Fortschr Röntgenstr 2019; 191: 1099 - 1106.