Effectiveness of wedge filter application in reducing lens radiation dose during diagnostic cerebral angiography: a phantom and prospective study.

Objective: Diagnostic cerebral angiography poses a risk of direct radiation exposure to the eye lens. This study aimed to evaluate the effectiveness of using a wedge filter to reduce lens exposure during examination.

Methods: A phantom study was initially conducted to evaluate the efficacy and determine the optimal depth of the wedge filter. Twenty patients with intracranial aneurysms scheduled for diagnostic cerebral angiography were prospectively enrolled. For each patient, the lens dose reduction protocol (involving a wedge filter) was used on one internal carotid artery (ICA), whereas the standard protocol was applied to the other ICA. Photoluminescent glass dosimeters were used to measure the lens dose. Quantitative noise measurements and qualitative analysis were performed to assess image quality.

Results: The phantom study demonstrated that the wedge filter reduced the radiation dose to the eye lens in anteroposterior (25.5% reduction at 4 cm depth) and lateral projections (28.8% reduction at 3 cm depth). In the patient study (20 patients, 60% female, mean age 57.5 years), the lens dose reduction protocol reduced the dose by 47.2% compared with the standard protocol (median 1.06 mGy vs 0.56 mGy, p < 0.001). In both protocols, the left lens dose was significantly higher than the right (standard: 1.37 mGy vs 0.70 mGy, p < 0.001; reduction: 0.75 mGy vs 0.36 mGy, p < 0.001). No significant differences were observed in image noise or quality.

Conclusion: The wedge filter significantly reduced the lens radiation dose during cerebral angiography without affecting image quality.

Key points: Question The radiation dose to the eye lens during cerebral angiography remains unclear; a targeted method is needed to selectively reduce exposure to this radiosensitive organ. Findings This study directly measured eye lens radiation dose and found that using a wedge filter reduces exposure by nearly half while maintaining diagnostic image quality. Clinical relevance Using a wedge filter during routine neuroangiography effectively reduces eye lens radiation exposure with a simple operation, preserving image quality and potentially lowering the risk of radiation-induced cataracts.