RESUMO
PURPOSE: Cross-sectional imaging by computed tomography (CT) is associated with higher radiation dose compared to plain X-ray. The Uro Dyna-CT provides CT-like images in the endourological operating room. Our aim was to reduce the radiation exposure of endourological patients with the Uro Dyna-CT and optimize the cross-sectional image quality. MATERIALS AND METHODS: For the hard contrast protocol, two artificial stones were placed in a Rando-Alderson phantom's left kidney region. Relevant parameters of the standard abdomen protocol were changed. After each modification, two urologists subjectively evaluated the image quality. We developed two customized protocols (standard, low-dose) for hard contrast imaging. To optimize the examination protocol for soft tissue imaging a standardized cone beam phantom was used. Parameters of the preset high-resolution protocol were changed to develop a protocol with similar objective image quality but lower radiation dose. To evaluate the effective radiation dose we embedded 129 thermoluminescence dosimeters in the kidney and ureter region of the Rando-Alderson phantom and performed each protocol five times (stone, soft tissue) and ten times (low-dose protocol). Mean effective dose values per 3D-examination were calculated. RESULTS: We detected a dose area product (DAP) 776.2 (standard) and 163.5 µGym(2) (low-dose) for the stone protocols with an effective dose of 1.96 and 0.33 mSv, respectively. The soft tissue protocol produced a DAP of 5,070 µGym(2) and an effective dose of 7.76 mSv. CONCLUSION: Our newly developed examination protocols for the Uro Dyna-CT provide CT-like image quality during urological interventions with low radiation dose.