Centre de recherche du Centre hospitalier universitaire de Sherbrooke (CRCHUS), Sherbrooke, Québec, Canada; Centre intégré universitaire de santé et de services sociaux de l'Estrie - Centre hospitalier universitaire de Sherbrooke (CIUSSS de l'Estrie - CHUS), Sherbrooke, Québec, Canada.
Centre de recherche du Centre hospitalier universitaire de Sherbrooke (CRCHUS), Sherbrooke, Québec, Canada; Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada.
Eur J Radiol. 2021 Sep;142:109861. doi: 10.1016/j.ejrad.2021.109861. Epub 2021 Jul 13.
To investigate retrospective classification of adult patients into small, average, and large based on effective diameter (EDia) from localizer image of computed tomography (CT) scans and to develop regional diagnostic reference levels (DRLs) and achievable doses (AD).
The patients falling within the mean ± standard deviation (SD) of EDia were classified as average; those below this range as small and above as large. The CTDIdose-length-product (DLP) and size-specific dose estimates (SSDE) of all adult patients undergoing CT examinations in 8 CT facilities for 11 months (Dec. 2019 - Oct. 2020) were evaluated. The 75th and 50th percentile values were compared with national and international values.
Of the total of 69,434 CT examinations, nearly 80% fell within average size. The 75th percentile values of CTDI and DLP for small patients for abdomen-pelvic exams were nearly half of average sized patients. Similarly, the 75th percentile values for large patients were nearly double. Similar findings were not found for chest exams. Analysis of image quality and dose factors such as noise, mean axial length, slice thickness, mean number of sequences, use of iterative reconstruction and tube current modulation (TCM) resulted in identification of opportunities for improvement and optimization of different CT facilities.
DRLs for adult patients were found to vary widely with patient size and thus establishing DRLs only for standard sized patient is not adequate. Simplified and intuitive methods for size classification was shown to provide meaningful information for optimization for patients outside the standard size adult.
通过对 CT 定位图像的有效直径（EDia）进行回顾性分类，将成年患者分为小、中、大三类，并制定区域性诊断参考水平（DRL）和可实现剂量（AD）。
将 EDia 平均值±标准差范围内的患者归类为平均体型；小于该范围的为小体型，大于该范围的为大体型。评估了 8 家 CT 设施在 11 个月（2019 年 12 月至 2020 年 10 月）期间所有接受 CT 检查的成年患者的 CTDI dose-length-product（DLP）和体型特异性剂量估计值（SSDE）。比较了第 75 百分位和第 50 百分位值与国内外值的差异。
在总共 69434 次 CT 检查中，近 80%的患者属于平均体型。腹部-盆腔检查中小体型患者的 CTDI 和 DLP 的第 75 百分位值接近平均体型患者的一半。同样，大体型患者的第 75 百分位值几乎是平均体型的两倍。胸部检查未发现类似的结果。对图像质量和剂量因素（如噪声、平均轴向长度、层厚、平均序列数、使用迭代重建和管电流调制（TCM））进行分析，确定了不同 CT 设施改进和优化的机会。
发现成年患者的 DRL 随患者体型差异很大，因此仅为标准体型患者制定 DRL 是不够的。体型分类的简化和直观方法为标准体型以外的患者提供了有意义的优化信息。
