Williams J R, Montgomery A
Department of Medical Physics and Medical Engineering, Western General Hospital, Edinburgh, UK.
Br J Radiol. 2000 Sep;73(873):1002-6. doi: 10.1259/bjr.73.873.11064656.
The National Radiological Protection Board (NRPB) has recommended the introduction of dose-width product (DWP) for the measurement of patient dose in panoramic dental radiology and has proposed a reference level of 65 mGy mm for adult exposures. This paper describes a method for measuring DWP and dose-area product (DAP) using thermoluminescent dosemeters (TLDs). The technique was used on 16 sets with a range of exposure settings. The mean value of DWP was 14% higher than the mean value reported from a survey by the NRPB. This difference is most likely to be caused by systematic variations due to measurement method. The average DAP for a standard adult examination was shown to be 11.3 cGy cm2. Data are presented so that the DAP can be derived from the exposure factors (tube current and operating potential) and beam area. Based on published data for effective dose, it is estimated that the DAP to effective dose conversion factor is approximately 0.06 mSv(Gy cm2)-1. The average DAP value (11.3 cGy cm2) can be compared with the average value for intraoral radiography (9.3 cGy cm2) based on the NRPB survey of entrance surface doses assuming 6 cm circular collimation.
国家放射防护委员会（NRPB）建议在全景牙科放射学中引入剂量宽度乘积（DWP）来测量患者剂量，并提出成人照射的参考水平为65 mGy·mm。本文描述了一种使用热释光剂量计（TLD）测量DWP和剂量面积乘积（DAP）的方法。该技术应用于16组具有一系列曝光设置的情况。DWP的平均值比NRPB调查报道的平均值高14%。这种差异很可能是由测量方法导致的系统变化引起的。标准成人检查的平均DAP显示为11.3 cGy·cm²。给出了相关数据，以便能根据曝光因素（管电流和工作电压）及射束面积得出DAP。根据已发表的有效剂量数据，估计DAP与有效剂量的转换因子约为0.06 mSv/(Gy·cm²)。基于NRPB对入口表面剂量的调查（假设采用6 cm圆形准直），可将平均DAP值（11.3 cGy·cm²）与口腔内放射摄影的平均值（9.3 cGy·cm²）进行比较。
