Influence of safety glasses, body height and magnification on the occupational eye lens dose during pelvic vascular interventions: a phantom study.

OBJECTIVE: By simulating a fluoroscopic-guided vascular intervention, two differently designed radiation safety glasses were compared. The impacts of changing viewing directions and body heights on the eye lens dose were evaluated. Additionally, the effect of variable magnification levels on the arising scattered radiation was determined. METHODS: A phantom head, replacing the operator's head, was positioned at different heights and rotated in steps of 20° in the horizontal plane. Thermoluminescent dosimeters (TLD), placed in the left orbit of the phantom, detected eye lens doses under protected and completely exposed conditions. In a second step, radiation dose values with increasing magnification levels were detected by RaySafe i3 dosimeters. RESULTS: Changing eye levels and head rotations resulted in a wide range of dose reduction factors (DRF) from 1.1 to 8.5. Increasing the vertical distance between the scattering body and the protective eyewear, DRFs markedly decreased for both glasses. Significant differences between protection glasses were observed. Increasing magnification with consecutively decreasing FOV size variably reduced the dose exposure to the eye lens between 47 and 83%, respectively. CONCLUSION: The safety glasses in the study effectively reduced the dose exposure to the eye lens. However, the extent of the protective effect was significant depending on eye levels and head rotations. This may lead to a false sense of safety for the medical staff. In addition, the application of magnification reduced the quantity of scattering dose significantly. To ensure safe working in the Cath-lab, additional use of protective equipment and the differences in design of protective eyewear should be considered. KEY POINTS: • Eye lens dose changes with physical size of the interventionist and viewing direction. • The use of magnification during fluoroscopic-guided interventions reduces scattered radiation.

Surface radiation dose comparison of a dedicated extremity cone beam computed tomography (CBCT) device and a multidetector computed tomography (MDCT) machine in pediatric ankle and wrist phantoms.

OBJECTIVES: To evaluate and compare surface doses of a cone beam computed tomography (CBCT) and a multidetector computed tomography (MDCT) device in pediatric ankle and wrist phantoms. METHODS: Thermoluminescent dosimeters (TLD) were used to measure and compare surface doses between CBCT and MDCT in a left ankle and a right wrist pediatric phantom. In both modalities adapted pediatric dose protocols were utilized to achieve realistic imaging conditions. All measurements were repeated three times to prove test-retest reliability. Additionally, objective and subjective image quality parameters were assessed. RESULTS: Average surface doses were 3.8 ±2.1 mGy for the ankle, and 2.2 ±1.3 mGy for the wrist in CBCT. The corresponding surface doses in optimized MDCT were 4.5 ±1.3 mGy for the ankle, and 3.4 ±0.7 mGy for the wrist. Overall, mean surface dose was significantly lower in CBCT (3.0 ±1.9 mGy vs. 3.9 ±1.2 mGy, p<0.001). Subjectively rated general image quality was not significantly different between the study protocols (p = 0.421), whereas objectively measured image quality parameters were in favor of CBCT (p<0.001). CONCLUSIONS: Adapted extremity CBCT imaging protocols have the potential to fall below optimized pediatric ankle and wrist MDCT doses at comparable image qualities. These possible dose savings warrant further development and research in pediatric extremity CBCT applications.

Covered stents in transjugular portosystemic shunt: healing response to non-porous ePTFE covered stent grafts with and without intraluminal irradiation.

The aim of this study was to evaluate the healing response to a new commercially available ePTFE-covered stent graft used to create transjugular intrahepatic portosystemic shunts (TIPS) in an animal model with and without intraluminal irradiation. The study was designed for ten domestic normotensive pigs. The TIPS was created using a ePTFE-covered stent graft (Viatorr, Gore, Flagstaff, Ariz.). Five animals were scheduled for intraluminal irradiation with iridium 192 immediately after TIPS creation with a dosage of 18 Gy. Shunt venograms were performed every 2 weeks. Animals from the irradiated and non-irradiated group were killed at 2-week intervals. Maximum follow-up was planned for 8 weeks in each group, with two animals in reserve. Gross specimen evaluation and histological examination, including scanning electron microscopy, was performed. Two animals died from interventional complications. In the irradiation group, one shunt occlusion and one stenosis occurred after 2 weeks. The stenosis regressed until the end of the 8-week follow-up period and probably was caused by a resolving thrombus. In the non-irradiated group, no shunt dysfunction was observed. One animal died early due to encephalopathy. Histology revealed an increased inflammatory reaction in the irradiation group, a lesser degree of incorporation of the stent graft, and a lesser degree of endothelialization of the inner surface compared with the non-irradiated group. No significant foreign body reaction was found at any time in any of the animals. The Viatorr stent graft was well tolerated in the pig model. Intraluminal irradiation seemed to have an adverse effect on the healing response. The TIPS patency was prolonged in both the irradiated and non-irradiated group compared with data from the literature; however, seemingly better results were observed in the non-irradiated group.