Stenström B, Rehnmark-Larsson S, Julin P, Richter S
Swed Dent J. 1983;7(3):85-91.
The protective effect in the thyroid region from different types of radiation shielding at intraoral radiography has been studied as well as the reduction of the absorbed dose to the sternal and the gonadal regions. The shielding tested were the different types of leaded aprons, of which three had an attached leaded collar and the other two were used in combination with separate soft leaded collars. Furthermore one of the soft leaded collars and an unflexible horizontal leaded shield were tested separately. Two dental x-ray machines of 60 and 65 kVp with rectangular and circular tube collimators were used. The exposure times corresponded to speed group E film. The absorbed doses were measured with two ionization chambers. No significant difference in the protective effect in the thyroid gland could be found between the different types of radiation shieldings. There was a dose reduction by approximately a factor of 2 to the thyroid region down to 0.08 mGy per full survey using parallelling technique, and below 0.001 mGy per single bitewing exposure. The shielding reduced the thyroid dose using bisecting-angle technique by a factor of 5 down to 0.15 mGy per full survey (20 exposures). In the sternal region the combinations of apron and collar reduced the absorbed dose from a full survey to below 2 microGy compared with 18 microGy (parallelling) and 31 microGy (bisecting-angle) without any shielding. With the horizontal leaded shield a reduction by a factor of 6 was obtained, but no significant sternal dose reduction could be detected from the soft collar alone. The gonadal dose could be reduced by a factor of 10 with the horizontal leaded shield, parallelling technique and circular collimator. Using leaded aprons the gonadal was approximately one per cent of the dose without any shielding, i.e. below 0.01 microGy per single intraoral exposure.
研究了口腔内放射摄影时不同类型辐射屏蔽对甲状腺区域的防护效果，以及对胸骨和性腺区域吸收剂量的降低情况。所测试的屏蔽物为不同类型的铅围裙，其中三件配有铅领，另外两件与单独的软质铅领配合使用。此外，还分别测试了其中一个软质铅领和一个不可弯曲的水平铅质屏蔽物。使用了两台管电压分别为60和65 kVp、带有矩形和圆形管准直器的牙科X射线机。曝光时间对应于E速组胶片。用两个电离室测量吸收剂量。不同类型的辐射屏蔽物之间在甲状腺的防护效果上未发现显著差异。使用平行技术时，甲状腺区域的剂量降低了约2倍，每次全景检查降至0.08 mGy，单次咬合翼片曝光低于0.001 mGy。使用分角技术时，屏蔽物使甲状腺剂量降低了5倍，每次全景检查（20次曝光）降至0.15 mGy。在胸骨区域，围裙和铅领的组合使吸收剂量从全景检查降至2 μGy以下，而无任何屏蔽时分别为18 μGy（平行技术）和31 μGy（分角技术）。使用水平铅质屏蔽物时剂量降低了6倍，但单独使用软质铅领未检测到胸骨剂量有显著降低。使用水平铅质屏蔽物、平行技术和圆形准直器时，性腺剂量可降低10倍。使用铅围裙时，性腺剂量约为无任何屏蔽时剂量的1%，即每次口腔内曝光低于0.01 μGy。
