Holroyd John
Public Health England, Chilton, Didcot OX11 0RQ, United Kingdom.
J Radiol Prot. 2018 Jun;38(2):793-806. doi: 10.1088/1361-6498/aabce3. Epub 2018 Apr 10.
The aim of this study was to quantify the levels of transmitted radiation arising from the use of intra-oral dental x-ray equipment and scattered radiation arising from the use of both intra-oral and panoramic x-ray equipment. Levels of scattered radiation were measured at 1 m from a phantom, using an ion chamber with a volume of 1800 cm. Transmitted radiation was measured using both (i) a phantom and dose-area product (DAP) meter and (ii) a patient and a 1800 cm ion chamber. For intra-oral radiography the patient study gave a maximum transmission of 1.80% (range 0.04-1.80%, mean 0.26%) and the phantom study gave a maximum transmission of 6% (range 2-6%, mean 5%). The maximum scattered radiation, per unit DAP, was 5.5 nGy (mGy cm) at 70 kVp and a distance of 1 m. For panoramic radiography the maximum scattered radiation was 9.3 nGy (mGy cm) at 80 kVp and a distance of 1 m. Dose values are presented to enable the calculation of adequate protective measures for dental radiography rooms. Previous studies have used a phantom and measured radiation doses at 1 m from the phantom to determine the radiation dose transmitted through a patient, whereas this study uses both patient and phantom measurements together with a large-area dosemeter, positioned to capture the entire x-ray beam, to ensure that more realistic dose measurements can be made.
本研究的目的是量化使用口腔内牙科X射线设备产生的透射辐射水平以及使用口腔内和全景X射线设备产生的散射辐射水平。使用体积为1800 cm的电离室在距模体1 m处测量散射辐射水平。使用（i）模体和剂量面积乘积（DAP）仪以及（ii）患者和1800 cm电离室测量透射辐射。对于口腔内X射线摄影，患者研究得出的最大透射率为1.80%（范围0.04 - 1.80%，平均0.26%），模体研究得出的最大透射率为6%（范围2 - 6%，平均5%）。在70 kVp和1 m距离处，每单位DAP的最大散射辐射为5.5 nGy/(mGy·cm)。对于全景X射线摄影，在80 kVp和1 m距离处，最大散射辐射为9.3 nGy/(mGy·cm)。给出剂量值以便计算牙科X射线摄影室的适当防护措施。以往的研究使用模体并在距模体1 m处测量辐射剂量来确定透过患者的辐射剂量，而本研究同时使用患者和模体测量，并结合一个大面积剂量仪，其位置可捕获整个X射线束，以确保能够进行更实际的剂量测量。
