Diagnostic Imaging Department, QE II Health Sciences Centre, Halifax, Nova Scotia, Canada.
Can Assoc Radiol J. 2012 Nov;63(4):237-41. doi: 10.1016/j.carj.2011.02.004. Epub 2011 Dec 2.
To establish local diagnostic reference levels (DRL) for typical radiographic examinations in a fully digital imaging institution.
The initial survey included 6 standard radiographic projections performed in 19 computed radiography (CR) and digital radiography (DR) rooms. Because of the expected difference in the performance, the local reference levels were analysed separately for those 2 modalities. Data of 226 average size adult patients were included in the analysis. Entrance surface dose (ESD) was calculated from the recorded radiographic techniques and tube radiation output measurements. After observing wide variations in the results of the patient survey, the examinations were repeated by using anthropomorphic phantoms. Initial efforts to understand the reasons for dose variations were focused on CR chest, abdomen, pelvis, and lumbar spine examinations.
The average size patient doses for similar examinations were lower in the DR rooms than in the CR rooms by factors that ranged from 1.2 to 3, with the exception of the chest examination. Standardization of the CR exposure index value allowed us to decrease ESD by 21%-30%. Detector sensitivity had an insignificant effect (2%) on ESD; proper collimation lowered the dose by 17%. However, the major effect, up to 46% difference, was found because of antiscatter grids cutoff.
Modality specific local diagnostic reference levels for standard examinations have been established in a large digital imaging department with hybrid modalities. Typically the local reference values were lower than those recommended in Safety Code 35, except for CR chests. Factors that affect the dose variations have been investigated and determined.
在完全数字化成像机构中为典型放射学检查建立局部诊断参考水平（DRL）。
初始调查包括在 19 个计算机射线照相（CR）和数字射线照相（DR）室中进行的 6 项标准射线照相投影。由于预期两种模式的性能存在差异，因此分别对这两种模式进行了局部参考水平分析。在分析中包括了 226 名普通成人患者的数据。从记录的射线照相技术和管辐射输出测量中计算出体表剂量（ESD）。在观察到患者调查结果存在广泛差异之后，使用人体模型对检查进行了重复。最初的努力是集中在理解剂量变化的原因，重点是 CR 胸部、腹部、骨盆和腰椎检查。
在 DR 室中，类似检查的平均大小患者剂量比 CR 室低 1.2 到 3 倍，除了胸部检查。CR 曝光指数值的标准化使我们能够将 ESD 降低 21％-30％。探测器灵敏度对 ESD 的影响不大（2％）；适当的准直可使剂量降低 17％。但是，由于反散射栅截止，主要的影响高达 46％的差异。
在具有混合模式的大型数字化成像部门中，已经为标准检查建立了特定于模式的局部诊断参考水平。通常，局部参考值低于安全代码 35 中建议的值，除了 CR 胸部。已经调查并确定了影响剂量变化的因素。
