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Tin filtration - how it influencs the radiation exposure received by patient in low--dose computed tomography of sacroiliac joints?

Publication at Faculty of Medicine in Pilsen |


Objectives: The objective of our study was to determine whether tin filtration reduces the radiation exposure received by patients and whether it affects the quality of imaging in low-dose computed tomography (LDCT) of sacroiliac joints (SIJ). The evaluation was performed on a group of patients with suspected ankylosing spondylitis.

For comparison, the effective dose of a conventional X-ray was calculated. Method: Patients examined by LDCT SIJ at our workplace in 2019-2020 were divided into two groups.

The first group underwent a low-dose protocol without the use of tin filtration and the second group underwent the same low-dose protocol with tin filtration. When a patient had an X-ray available in the clinical system, its effective dose was calcu-lated.

The dose evaluation were performed by a medical physicist using ImpactDose 2.3, patient model - real patient data (CT Imaging GmbH, Germany) and PCXMC 2.0 (X-ray, STUK Finland) programs. The quality of the image documentation was evaluated independently by two radiologists.

Results: In our cohort, the median effective dose for LDCT with tin filtration was 0.1 mSv (0.05-0.18 mSv), for LDCT without tin filtration was 0.5 mSv (0.3-0.9 mSv) and for X-ray was 0.25 mSv (0.06-1.16 mSv). In both LDCT groups 90% of image documentation was of an excellent quality.

Conclusion: Our results showed that the tin filtration decreases the radiation dose in comparison with the low-dose protocol by 80%. Compared to X-rays, the dose in our LDCT group with tin filtration was 50% lower.

It follows that LDCT with tin filtration can be used in the diagnosis of ankylosing spondylitis instead of X-rays or in case of unclear findings or inability to perform MRI examination. (C) 2021, Galen s.r.o.. All rights reserved.