Tse Jason, McLean Donald
Canberra Hospital.
J Appl Clin Med Phys. 2015 Jul 8;16(4):244–253. doi: 10.1120/jacmp.v16i4.5439.
This study investigated the clinical performance of a novel solid-state diagnostic dosimeter, the RaySafe Xi transparent detector, by comparing its performance to a reference-class ionization chamber. Firstly a comparison of dosimeter response "free-in-air" with standard beam qualities was made, followed by an investigation into its relative transparency in an X-ray field and angular sensitivity dependence. The second part of the study looked at the overall performance of the transparent detector under scatter conditions with a number of beam qualities, including standard beam and those hardened by copper (Cu) filtration of thickness up to 0.9 mm, as would be encountered in the equipment testing of fluoroscopy systems. Overall, the transparent detector has demonstrated equivalent measurement properties to the ionization chamber under standard conditions and provided similar X-ray attenuation as reflected by the nearly identical radiographic parameters selected for both dosimeters by the automatic dose rate control (ADRC) system. Yet, it also possessed an asymmetric angular response which respectively under- and overestimated the dose contribution from the rear and lateral directions by the same amount of 50%. The transparent detector provided comparable dose reading of ± 3% to the ionization chamber with standard beam qualities and backscatter radiation present. These results were in good agreement with those of free-in-air measurement, indicating that the angular under- and overresponse might potentially compensate one another for accurate measurement. However, for identical Cu filtered beam qualities and setups, the transparent detector on average overresponded by 5.4% across the useful tube voltage range. In conclusion, the transparent detector, with its novel design, is essentially equivalent, within a 5% tolerance, to an ionization chamber, except in situations where beams hardened with Cu filtration are used with backscatter radiation present requiring larger uncertainty error estimations.
本研究通过将新型固态诊断剂量仪RaySafe Xi透明探测器的性能与参考级电离室进行比较，来研究其临床性能。首先，对剂量仪在“空气自由”状态下与标准射束质量的响应进行了比较，随后研究了其在X射线场中的相对透明度以及角度灵敏度依赖性。研究的第二部分考察了透明探测器在多种射束质量的散射条件下的整体性能，这些射束质量包括标准射束以及在荧光透视系统设备测试中会遇到的经厚度达0.9毫米的铜（Cu）过滤硬化后的射束。总体而言，透明探测器在标准条件下已证明具有与电离室相当的测量特性，并且提供了相似的X射线衰减，这体现在自动剂量率控制（ADRC）系统为两个剂量仪选择的几乎相同的射线照相参数上。然而，它也具有不对称的角度响应，分别低估和高估了来自后方和侧向方向相同数量50%的剂量贡献。在存在标准射束质量和反向散射辐射的情况下，透明探测器提供了与电离室相当的±3%的剂量读数。这些结果与空气自由测量的结果高度一致，表明角度上的低估和高估响应可能会相互补偿以实现准确测量。然而，对于相同的经Cu过滤的射束质量和设置，在整个有用管电压范围内，透明探测器平均过度响应了5.4%。总之，除了在使用经Cu过滤硬化的射束且存在反向散射辐射需要更大不确定性误差估计的情况下，具有新颖设计的透明探测器在5%的公差范围内与电离室基本等效。
