Comparative dosimetry of dental cone-beam computed tomography and multi-slice computed tomography for oral and maxillofacial radiology / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare the effective radiation dose levels of cone beam computed tomography (CBCT) with those of multi-slice computed tomography (MSCT) when scanning the same maxillofacial regions.</p><p><b>METHODS</b>The effective doses of 2 CBCT (NewTom 9000 and DCT Pro) and 1 MSCT (bright speed edge select 8 slice) scanners were calculated using thermoluminescent dosimeters (TLD) that were placed in a head and neck phantom, and expressed according to the International Commission on Radiation Protection (ICRP) 2007 guidelines.</p><p><b>RESULTS</b>Effective dose values ranged from 41.8 to 249.1 µSv for CBCT. The doses of MSCT scanning for maxilla, mandible and maxilla + mandible were 506.7, 829.9 and 1066.1 µSv, respectively. Dose levels of scanning only for maxilla or mandible were significantly lower than those for maxilla + mandible.</p><p><b>CONCLUSIONS</b>When scanning the same maxillofacial regions, the dose levels for NewTom 9000 and DCT Pro CBCT images were lower than those for Bright speed edge select 8 slice MSCT images. Dose levels reduction could be obtained when smaller regions were scanned.</p>

Effect of radiation on the activity and expression of Ca(2+)-Mg(2+)-ATPase in rat masseter muscle / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the activity and expression of Ca(2+)-Mg(2+)-ATPase in irradiated rat masseter muscle.</p><p><b>METHODS</b>The rats were irradiated locally with a single dose of 20 Gy X-ray. The activities of Ca(2+)-Mg(2+)-ATPase were measured with colorimetric method. The protein expression of Ca(2+)-Mg(2+)-ATPase was determined by Western blotting and immunohistochemistry.</p><p><b>RESULTS</b>The activities of Ca(2+)-Mg(2+)-ATPase in masseter muscle decreased by approximately 20% and 40% in irradiated rats on days 3 and 30 postirradiation. There was significant difference in the expression of Ca(2+)-Mg(2+)-ATPase protein between irradiated and nonirradiated rats on day 30 postirradiation. Ca(2+)-Mg(2+)-ATPase protein was found in the cytoplasm of masseter muscle.</p><p><b>CONCLUSIONS</b>The decrease of ATPase activity played an important role in the cause of radiation-induced skeletal muscle injury, while there was no significant reduction in the expression of Ca(2+)-Mg(2+)-ATPase protein in irradiated rat masseter muscle.</p>