Chan Lung-Sang, Cheung Giselle T Y, Lauder Ian J, Kumana Cyrus R, Lauder Ian J
Department of Earth Sciences, The University of Hong Kong, Hong Kong.
J Travel Med. 2004 Sep-Oct;11(5):273-9. doi: 10.2310/7060.2004.19102.
Following the severe acute respiratory syndrome (SARS) outbreak, remote-sensing infrared thermography (IRT) has been advocated as a possible means of screening for fever in travelers at airports and border crossings, but its applicability has not been established. We therefore set out to evaluate (1) the feasibility of IRT imaging to identify subjects with fever, and (2) the optimal instrumental configuration and validity for such testing.
Over a 20-day inclusive period, 176 subjects (49 hospital inpatients without SARS or suspected SARS, 99 health clinic attendees and 28 healthy volunteers) were recruited. Remotely sensed IRT readings were obtained from various parts of the front and side of the face (at distances of 1.5 and 0.5 m), and compared to concurrently determined body temperature measurements using conventional means (aural tympanic IRT and oral mercury thermometry). The resulting data were submitted to linear regression/correlation and sensitivity analyses. All recruits gave prior informed consent and our Faculty Institutional Review Board approved the protocol.
Optimal correlations were found between conventionally measured body temperatures and IRT readings from (1) the front of the face at 1.5m with the mouth open (r=0.80), (2) the ear at 0.5 m (r=0.79), and (3) the side of the face at 1.5m (r=0.76). Average IRT readings from the forehead and elsewhere were 1 degrees C to 2 degrees C lower and correlated less well. Ear IRT readings at 0.5 m yielded the narrowest confidence intervals and could be used to predict conventional body temperature readings of < or = 38 degrees C with a sensitivity and specificity of 83% and 88% respectively.
IRT readings from the side of the face, especially from the ear at 0.5 m, yielded the most reliable, precise and consistent estimates of conventionally determined body temperatures. Our results have important implications for walk-through IRT scanning/screening systems at airports and border crossings, particularly as the point prevalence of fever in such subjects would be very low.
在严重急性呼吸综合征（SARS）疫情爆发后，有人主张使用遥感红外热成像技术（IRT）作为在机场和边境口岸筛查旅行者发热情况的一种可能手段，但尚未确定其适用性。因此，我们着手评估：（1）IRT成像识别发热受试者的可行性；（2）此类检测的最佳仪器配置及有效性。
在为期20天（含）的时间段内，招募了176名受试者（49名无SARS或疑似SARS的住院患者、99名健康诊所就诊者和28名健康志愿者）。从面部正面和侧面的不同部位（距离分别为1.5米和0.5米）获取遥感IRT读数，并与同时使用传统方法（耳鼓膜IRT和口腔水银体温计）测定的体温进行比较。将所得数据进行线性回归/相关性和敏感性分析。所有受试者均事先签署知情同意书，且我们学院的机构审查委员会批准了该方案。
在以下情况中，传统测量的体温与IRT读数之间发现了最佳相关性：（1）距离面部正面1.5米且张嘴时（r = 0.80）；（2）距离耳部0.5米时（r = 0.79）；（3）距离面部侧面1.5米时（r = 0.76）。前额及其他部位的平均IRT读数低1摄氏度至2摄氏度，且相关性较差。距离耳部0.5米处的IRT读数产生的置信区间最窄，可用于预测体温读数≤38摄氏度，其敏感性和特异性分别为83%和88%。
面部侧面，尤其是距离耳部0.5米处的IRT读数，对传统测定的体温给出了最可靠、精确和一致的估计。我们的结果对机场和边境口岸的通过式IRT扫描/筛查系统具有重要意义，特别是鉴于此类受试者中发热的点患病率会非常低。
