Establishment of diagnostic reference levels for dentomaxillofacial radiography in Japan

本研究的目的是建立诊断参考水平（DRL）的牙颌面放射摄影在日本，以促进优化患者的放射防护和管理患者的剂量在常规X射线检查。为了评价这些DRL，我们研究了辐射量和辐射测量方法，然后调查了大学牙科医院和牙科诊所的辐射量和患者剂量，使用便携式剂量计和X射线胶片进行区域调查，使用电离室进行局部调查，由日本质量保证组织校准。将电离室与口内X线光释光剂量计和全景X线热释光剂量计组成的便携式剂量计进行了比较，确定了标准成人剂量分布的第三四分位数DRL：（1）口内X线：患者入射剂量，PED=2.1 mGy，剂量-面积乘积DAP=59 mGy cm ^2;但对于D-速度胶片，应加倍PED或DAP，DAP应根据PED与矩形野面积的乘积计算;（2）全景摄影：剂量宽度乘积，DWP=65 mGy mm，DAP=113 mGy cm^2 ;（3）头影测量X线摄影：入射表面空气比释动能，ESAK=0.4 mGy，但由于使用楔形滤波器和楔形辐射野，因此未提出DAP;（4）计算机断层扫描（CT），用于计划双颌牙种植手术：加权CT剂量指数CTDI_w=35 mGy，剂量长度乘积DLP=360 mGy/cm，但每个颌的DLP为1/2，这些DRL与欧洲建议的DRL几乎相同，日本应在牙科X线检查中实现这些DRL，以保持足够的管电位、射束过滤和高灵敏度的图像接收系统。

The objectives of this research were to establish diagnostic reference levels (DRLs) for dentomaxillofacial radiography in Japan in order to promote optimization of radiological protection for patients and to manage patient doses in routine X-ray examinations. For evaluation of these DRLs we studied the radiation quantities and methods of radiation measurement, and then surveyed the quantities and patient doses in university dental hospitals and in dental clinics.Transportable dosimeters coupled with X-ray films were used for the regional area survey and ionization chambers were used for the local area survey, which were calibrated by the Japanese Quality Assurance Organization. The ionization chambers were compared with the transportable dosimeters which were composed by an optically stimulate luminescence dosimeter for intraoral radiography and a thermoluminescent dosimeter array for panoramic radiography.From the results of the survey the DRLs were determined as a third quartile of the dose distributions for standard adults as follows : (1)intraoral radiography : patient entrance dose, PED=2.1 mGy and dose-area product, DAP=59 mGy cm^2 ; but a double of PED or DAP for D-speed films and the DAP should be calculated from the product of PED by the area of a rectangular field ; (2)panoramic radiography : dose-width product, DWP=65 mGy mm and DAP=113 mGy cm^2 ; (3)cephalometric radiography : entrance surface air kerma, ESAK=0.4 mGy, but DAP was not proposed because of the usage of wedge filters and radiation fields of wedge shapes ; (4)computed tomography (CT) for planning of dental implantation surgery of both jaws : weighted CT dose index, CTDI_w=35 mGy and dose-length product, DLP=360 mGy cm, but a half of DLP for each jaw.These DRLs, which are almost the same as those proposed in Europe, should be achieved in Japan to maintain adequate tube potentials, beam filtrations, and high sensitivity image receptor systems in dental radiographic examinations.