Ng Eddie Y K, Kaw G J L, Chang W M
School of Mechanical and Production Engineering, Nanyang Tech University, Singapore 639798, Singapore.
Microvasc Res. 2004 Sep;68(2):104-9. doi: 10.1016/j.mvr.2004.05.003.
Obtaining meaningful temperature for the human body requires identifying a body site that will provide reliable data across a large population. It is important to understand that skin temperature does not solely depend on body-core temperature and may be affected by other physiological and environmental factors. Currently, there is lack of empirical data in correlating facial surface temperature with body core temperature. Present IR systems in use at airports/immigration checkpoints have not been scientifically validated particularly in regards to the false-negative rate. As a result, they may create a false sense of security by underestimating the number of febrile (and possibly infected) individuals. This article evaluates the effectiveness of thermal scanner when it is being used for mass blind screening of potential fever subjects such as SARS or bird flu patients.
Bio-statistics with regression analysis and ROC is applied to analyse the data collected (502) from the SARS hospital in Singapore and conclusive results are drawn from them. The results are vital in determining two very important pieces of information: the best and yet practical region on the face to take readings and optimal pre-set threshold temperature for the thermal imager.
(1) The thermal scanner can be used as a first line tool for the mass blind screening of hyperthermia, (2) the readings from the scanner suggest good correlation with the ear temperature readings, (3) an imager temperature threshold should be determined by the environmental factors, outdoor condition in particular, the physiological site offset and the performance characteristics of thermal imager to warrant the most accurate and reliable screening operation.
The analysis suggested that the thermal imager used holds much promise for mass blind screening when the readings from a specific region have a good correlation with the ear temperature. From the regression analysis, the best reading is taken from the maximum temperature in the eye region, followed by the maximum temperature in the forehead region. With ROC analysis, a randomly selected individual from the fever group has a test value larger than that for a randomly selected individual from the normal group in 97.2% of the time. The test can distinguish between the normal and febrile groups and an optimum threshold temperature for the thermal imager can be found. The pre-set threshold cut-off temperature for the current thermal imager was found to be 36.3 degrees C with reference to the associated environmental condition. Any temperature readings that exceed this reading will trigger off the alarm and a thermometer will be used to verify the whether the person is having fever.
获取有意义的人体温度需要确定一个能在大量人群中提供可靠数据的身体部位。必须明白，皮肤温度并非仅取决于体核温度，还可能受其他生理和环境因素影响。目前，缺乏将面部表面温度与体核温度相关联的实证数据。机场/移民检查站目前使用的红外系统尚未经过科学验证，尤其是在假阴性率方面。因此，它们可能会低估发热（及可能感染）人员数量，从而营造出一种虚假的安全感。本文评估了热成像仪用于对非典或禽流感患者等潜在发热对象进行大规模盲筛时的有效性。
应用回归分析和ROC的生物统计学方法分析从新加坡非典医院收集的502份数据，并从中得出结论性结果。这些结果对于确定两条非常重要的信息至关重要：面部最佳且实用的读数区域以及热成像仪的最佳预设阈值温度。
（1）热成像仪可作为大规模盲筛体温过高情况的一线工具；（2）热成像仪的读数与耳部温度读数显示出良好的相关性；（3）成像仪温度阈值应由环境因素（尤其是室外条件）、生理部位偏差以及热成像仪的性能特征来确定，以确保最准确可靠的筛查操作。
分析表明，当特定区域的读数与耳部温度有良好相关性时，则所使用的热成像仪在大规模盲筛方面很有前景。通过回归分析，最佳读数取自眼部区域的最高温度，其次是前额区域的最高温度。通过ROC分析，发热组中随机选择的个体有97.²%的时间其测试值大于正常组中随机选择的个体。该测试能够区分正常组和发热组，并且可以找到热成像仪的最佳阈值温度。参照相关环境条件，发现当前热成像仪的预设阈值截止温度为36.3摄氏度。任何超过此读数的温度读数都会触发警报，然后会使用体温计来核实该人是否发烧。
