Estimating the radiation dose to the fetus during prophylactic internal iliac occlusion in patients with abnormal placentation.

AIMS: To evaluate the estimated fetal radiation dose during prophylactic internal iliac arterial occlusion in patients with abnormal placenta and to estimate the risk of radiation induced cancer in child age. METHODS: Prophylactic occlusion of the internal iliac arteries during Caesarean section was performed in 42 patients with placenta praevia and/or placenta accreta spectrum. Fogarty embolectomy catheters were used for prophylactic occlusion of the internal iliac arteries. All procedures were performed in the hybrid operating room using Philips Allura Xper FD 20 X-ray system. Low dose X-ray fluoroscopy (7.5 frames per second) was used. The CODE (Conceptus dose estimation) Software was used to estimate the fetal dose and the risk of radiation induced carcinoma. RESULTS: Fluoroscopy times required for insertion of Fogarty catheters were 0.5-4.2 min (mean: 1.7 min, median: 1.5 min). The estimated radiation dose to the fetus was 0.26-3.36 mGy (mean: 1.49 mGy, median: 1.25 mGy). The risk of radiation induced cancer in child age was 0.01-0.04% (mean 0.02%, median 0.01%). One patient developed thrombosis of a common femoral artery. CONCLUSION: Prophylactic occlusion of the internal iliac arteries is a simple and safe procedure with minimal risk of complications and with a very low estimated radiation dose to the fetus.

Biomimetic apatite formation on chemically treated titanium.

Titanium treated in NaOH can form hydroxycarbonated apatite (HCA) after exposition in simulated body fluid (SBF). Generally, titanium is covered with a passive oxide layer. In NaOH this passive film dissolves and an amorphous layer containing alkali ions is formed on the surface. When exposed to SBF, the alkali ions are released from the amorphous layer and hydronium ions enter into the surface layer, resulting in the formation of Ti-OH groups in the surface. The released Na(+) ions increase the degree of supersaturation of the soaking solution with respect to apatite by increasing pH, and Ti-OH groups induce apatite nucleation on the titanium surface. The acid etching of titanium in HCl under inert atmosphere was examined as a pretreatment to obtain a uniform initial titanium surface before alkali treatment. Acid etching in HCl leads to the formation of a micro-roughened surface, which remains after alkali treatment in NaOH. It was shown by SEM, gravimetric and solution analysis that the apatite nucleation was uniform and the thickness of precipitated HCA layer increased continuously with time. The treatment of titanium by acid etching in HCl and subsequently in NaOH is a suitable method for providing the metal implant with bone-bonding ability.

Hydroxyapatite formation on alkali-treated titanium with different content of Na+ in the surface layer.

Titanium can form a bone-like apatite layer on its surface in SBF when it is treated in NaOH. When pre-treated titanium is exposed to SBF, the alkali ions are released from the surface into the surrounding fluid. The Na+ ions increase the degree of supersaturation of the soaking solution with respect to apatite by increasing pH. On the other hand, the released Na+ cause an increase in external alkalinity that triggers an inflammatory response and leads to cell death. Therefore, it would be beneficial to decrease the release of Na+ into the surrounding tissue. The purpose of this study was to evaluate the hydroxyapatite formation on alkali-treated titanium with different content of Na+ in the surface layer. Using SEM, gravimetric analysis and measurement of calcium and phosphate concentration, it was found that the rate of apatite formation was not significantly influenced by a lower amount of Na+ in the surface layer. Titanium with the lowest content of Na+ could be more suitable for implantation in the human body. The amount of alkali ions released in the surrounding tissue is lower and the rate of apatite formation is identical to titanium with the highest content of Na+ in the surface layer.