Clinical applications of computerized thermography

Computerized or digital, thermography is a rapidly growing diagnostic imaging modality. It has superseded contact thermography and analog imaging thermography which do not allow effective quantization. Medical applications of digital thermography can be classified in two groups: static and dynamic imaging. They can also be classified into macro thermography (resolution greater than 1 mm) and micro thermography (resolution less than 100 microns). Both modalities allow a thermal resolution of 0.1 C. The diagnostic power of images produced by any of these modalities can be augmented by the use of digital image enhancement and image recognition procedures. Computerized thermography has been applied in neurology, cardiovascular and plastic surgery, rehabilitation and sports medicine, psychiatry, dermatology and ophthalmology. Examples of these applications are shown and their scope and limitations are discussed

Depth estimation of inner wall defects by means of infrared thermography

There two common methods dealing with interpreting data from infrared thermography: qualitatively and quantitatively. On a certain condition, the first method would be sufficient, but for an accurate interpretation, one should undergo the second one. This report proposes a method to estimate the defect depth quantitatively at an inner wall of petrochemical furnace wall. Finite element method (FEM) is used to model multilayer walls and to simulate temperature distribution due to the existence of the defect. Five informative parameters are proposed for depth estimation purpose. These parameters are the maximum temperature over the defect area (Tmax-def), the average temperature at the right edge of the defect (Tavg-right), the average temperature at the left edge of the defect (Tavg-left), the average temperature at the top edge of the defect (Tavg-top), and the average temperature over the sound area (Tavg-so). Artificial Neural Network (ANN) was trained with these parameters for estimating the defect depth. Two ANN architectures, Multi Layer Perceptron (MLP) and Radial Basis Function (RBF) network were trained for various defect depths. ANNs were used to estimate the controlled and testing data. The result shows that 100% accuracy of depth estimation was achieved for the controlled data. For the testing data, the accuracy was above 90% for the MLP network and above 80% for the RBF network. The results showed that the proposed informative parameters are useful for the estimation of defect depth and it is also clear that ANN can be used for quantitative interpretation of thermography data

Application of NDT thermographic imaging of aerospace structures

This work aims to address the effectiveness and challenges of Non-Destructive Testing (NDT) inspection and improve the detection of defects without causing damage to the material or operator. It focuses on two types of NDT methods; pulsed thermography and vibrothermography. The paper also explores the possibility of performing automated aerial inspection using an unmanned aerial vehicle (UAV) provided with a thermographic imaging system. The concept of active thermography is discussed for inspecting aircraft CFRP panels along with the proposal for performing aerial inspection using the UAV for real time inspection. Static NDT results and the further UAV research indicate that the UAV inspection approach could significantly reduce the inspection time, cost, and workload, whilst potentially increasing the probability of detection

Non destructive investigation of defects in composite structures by fullfield measurement methods

This paper presents different interests of non destructive full-field measurement. More precisely, it focuses on the characterization and the comparison of the X-ray tomography and two methods of infrared thermography in order to define the defect detection limits and to precise the specific application fields for each technique on multi-layered and sandwich composite structures. The obtained results are qualitatively and quantitatively analyzed

Non destructive investigation of defects in composite structures by three infrared thermographic techniques

This paper investigates full-field measurement techniques based on Infrared Thermography for Non Destructive Testing (NDT) applications on composite materials. Three methods have been implemented and the paper intends to characterize and compare their defect detection limit and related specific application fields. Various composites have been considered in this study, namely laminates and sandwich structures, in order to address many important issues of performance assessment for the aviation industry

Integrated dynamic and thermography investigation of Mallorca cathedral

An integrated investigation of engineering archaeometry was carried out using dynamic identification, dynamic monitoring and Infra-Red (IR) thermography for the study of the dynamic behavior of Mallorca cathedral in Spain. The cathedral is a large historical masonry structure built during 14-16th c. Dynamic identification and monitoring allowed the capturing of eight natural frequencies of the cathedral. IR thermography was used as a complementary inspection technique in the context of a continuous monitoring. Usually, IR thermography is used punctually for the inspection of a part of an inspected structure. Here an alternative was tried as the IR camera was installed for two two-weeks periods in the winter and in the summer of 2011 to monitor the stone surface temperature of a large portion of the cathedral. The correlation between the cathedral natural frequencies and the stone surface temperature of some selected structural elements was investigated and compared with the correlation with the external and the internal temperatures. It was found that the correlation with stone surface temperature was lower than that with external temperature. The study allowed a better understanding of the influence of temperature changes on the structure’s dynamic behavior.Peer ReviewedPostprint (published version

サーモグラフィーによる体表面温度の測定 2.温水負荷の効果

The body surface temperature of 41 patients suffering coldness, numbness or pain in their feet was examined using thermography. Thermographic results were analyzed quantitatively by calculating a recovery ratio as: Recovery ratio =[Total counts of thermography (Pixels) over temperature (T) after cold loading] ÷ [Initial counts over T before cold loading] x 100(%). Three different baseline temperatures, 26℃. 27℃ and 28℃, were used in processing the thermographic results into pictures. The recovery ratio was susceptible to temperature, and we recommend a baseline temperature limitation of 27℃ for clinical study. A bi-modal distribution of recovery ratio was observed in 18 patients with diabetes mellitus. One group (6 subjects) had high recovery ratio between 80%-100%, and another group (10 subjects) had a low recovery ratio between 0%-19%. The results of thermography were also influenced by weather. To reduce the effect of outside temperature, we used pre-loading with hot water at 36℃ for 5 min (hot loading).　A large difference in　recovery ratio between presence and absence of hot loading was observed in 6 of the 30 subjects. The difference was over-estimated in more than 20% of recovery ratio without hot loading as compared with hot loading in these 6 subjects. The effect of drugs on peripheral circulation, such as beraprost sodium and sarpogrelate hydrochloride, was clear and quantified using thermography under these conditions of hot loading.下肢に冷感ならびにしびれ感または疼痛を訴える患者41症例についてサーモグラフィーを用いて体表面温度を測定した｡測定で得られた結果は回復率として数量化して表示された｡回復率の算出方法は回復率=[冷水負荷後の特定温度T℃以上の体表面温度のサーモグラフィーのPixelの総数]÷[温水負荷前の特定温度T℃以上の体表面温度のサーモグラフィーのPixelの総数]× 100%で求めた｡サーモグラフィーで得られた結果と画像処理の過程で用いられた,26℃,27℃,28℃の3つの異なる特定温度T℃ との関連について検討を行なった｡その結果,回復率は特定温度T℃に影響を受けやすいことが明らかとなった｡下肢の体表面温度の低い臨床症例においては27℃の条件が適当と考えられた｡前述の41症例中の18症例の糖尿病患者について検討を行なった｡そのサーモグラフィーの結果は,比較的回復率の高い(80%～100%)群の6症例と比較的回復率の低い(0%～19%)群の10症例の2群に別れた｡わずかに残り2症例が20%から79%の間であった｡下肢の症状が気温の低い時期に出親しやすいためにサーモグラフィーの検査を冬期に行なう必要性が高まった｡しかし,天候の影響を受けやすいために冷水負荷前の測定領域の下肢が冷えすぎているために20℃の室温に15分間の安静時間では体表面温度が十分に暖まることが出来ず,27℃以上の領域として測定範囲全体を観察できない 問題に直面した｡この間温点を解決する手段として36℃の温水に5分間下肢を入れて暖める温水負荷を加えることにした｡そこで, 温水負荷を行なった症例30症例について,温水負荷を行なう前(室温)の回復率と温水負荷を行なった後の回復率について比較検討を行なったところ,20%にあたる6症例において温水負荷を行なわなかった場合に20%以上の回復率の過剰評価が認めら れた｡温水負荷を行なうことにより年間を通じて天候の影響を最小限にすることが可能となり,この結果,長期間の内服薬の末梢循環に及ぼす影響の測 定を行なった場合に,季節の影響を最小限にしてサーモグラフィーにより回復率を用いて数値化された測定結果を検討することが可能となった｡具体的に末梢循環の改善に薬効が有ると言われている薬剤であるベラプロストおよびサルポグレラートを3ヵ月間内服した場合の前後のサーモグラフィーで得られた回復率について検討を行なった｡その結果はベラプロストにおいては,6.9%から41.9%に上昇または回復率の6.1倍の上昇を認めた。サルポグレラートにおいては,1.9%から17.3%に上昇または回復率の9.1倍の上昇を認めた。以上より,温水負荷を加えたサーモグラフィーの測定結果の数値化は下肢に症状の有る患者の末梢循環の評価ならびに薬効の評価の比較に有用であることが表わされた

Degradation in Field-aged Crystalline Silicon Photovoltaic Modules and Diagnosis using Electroluminescence Imaging

Degradation phenomena observed in field-aged crystalline silicon photovoltaic modules include EVA browning, delamination between the glass-encapsulant and the cell-encapsulant interfaces, degradation of the anti-reflective coating, corrosion of busbars and contacts, cracks, humidity ingress, etc. The type and severity of the defects observed vary significantly between cells, modules and installations as affected by a number of both internal and external parameters. This study presents mild to severe degradation effects observed in crystalline silicon PV modules operating outdoors for different periods of time and investigated through non-destructive testing techniques including I-V characterisation, UV fluorescence, IR thermography and Electroluminescence (EL) Imaging. The identification and diagnosis of defects and further correlation to the electrical degradation of the module is achieved through the complementary contribution of these techniques. Severe electrical degradation and mismatch between the cells are identified through IR thermography and EL imaging. Diagnosis of rather uniformly degraded modules is enhanced through EL Imaging by which shunts, higher resistance regions, cracks, broken metallization are identified, while the module may appear to operate reliably. Signs of early degradation are further diagnosed through UV fluorescence and EL Imaging, allowing to monitor the evolution of defects and evaluate module reliability

サーモグラフィーによる体表面温度の測定 3.体表面温度の回復率と末消血流量との相関

The body surface peripheral circulation in 12 cases,　including 9 patients with　diabetes mellitus who were suffering coldness, numbness or pain in their feet, and 3 healthy volunteers was examined using Laser-Doppler blood flowmetry. At the same time, the body surface temperature was estimated by thermography. Thermographic results were analyzed quantitatively by calculating a recovery ratio as : Recovery ratio = [Total counts of thermography(Pixels) over temperature (T) after cold loading] ÷ [Initial counts over T before cold loading] x 100(%). The recovery ratio and the blood flow were correlated, r=0.68, p<O.01. The peripheral circulation of 16 patients with diabetes mellitus was observed at three different conditions including, l)placed at room temperature at 20℃for 15 min, 2) submerged and warmed for 5 min in a hot bath at 36℃(i.e. hot loading), and 3) submerged and cooled for 5 min in a water bath at 20℃ (i.e. cold loading). Three different baseline temperatures, 26℃, 27℃ and 28 ℃, were used in processing the　thermographic results into pictures. The highest correlation (r=0.59, p=0.0002) was obtained under the condition of cold loading using a baseline temperature limitation of27℃.The difference ratio (%) of blood flow was calculated as the blood flow at cold loading divided by the blood flow at hot loading in these 16 patients. The difference　ratio of the blood flow and the recovery ratio of thermography were correlated, r=0.46, p<O.OOO1. We found a strong correlation between the results of Laser-Doppler blood flowmetry and one of thermographic methods used to monitor peripheral circulation in patients with diabetes mellitus. Cold loading using a baseline temperature limitation of 27℃ were recommended for further examinations. Patients with low blood flow as well as　with large differences in their peripheral circulation between cold loading and hot　loading had severe coldness in their body surface temperature. We showed the usefulness of the results of thermography, when quantified by picture processing using computer software, in relation with the results of Laser-Doppler blood flowmetry.末梢神経障害を有する糖尿病患者の末梢循環障害の程度を数量的に検討する目的で､下肢に冷感ならびにしびれ感または疼痛を訴える糖尿病患者9症例と健常ボランティア3例の計12例(平均年齢59歳)についてサーモグラフィーを用いて体表面温度を測定した｡更に,サーモグラフィーで得られた結果と末梢皮膚血流量をレーザードプラー血流計を用いて測定して得られた結果と比較した｡サーモグラフィーによる測定で得られた結果は回復率として数量化して表示された｡回復率の算出方法は回復率= [冷水負荷後の特定温度27℃以 上の体表面温度のサーモグラフィーのPixelの総数]÷ [冷水負荷前の特定温度27℃以上の体表面温度のサーモグラフィーのPixelの総数]×100%で求めた｡レーザードプラ-血流計を用いて測定して得られた末梢血流量は左右それぞれ5カ所,計10カ所の測定値の平均で表示した｡その結果,末梢皮膚温度の回復率と末梢皮膚の血流量との問には正の相関関係(r=0.68,p<0.01)が認められた｡次に,末梢皮膚血流量について,室温20℃安静15分後,温水36℃浸水負荷10分後,冷水20℃浸水負荷30分後の異なる3条件について､またサーモグラフィーで得られた結果を,画像処理の過程で用いられた,26℃,27℃,28℃の3つの異なる特定温度との関連について検討を行なった｡対象は,下肢に冷感ならびにしびれ感または疼痛を訴える糖尿病患者16症例(平均年齢69歳,平均HbAIC9.6%)について測定した｡その結果,末梢皮膚 血流量は冷水20℃浸水負荷30分後に測定して得られた結果と,回復率は特定温度27℃で画像処理して得られた結果とが最も相関が高い(r=0.59,p=0.0002)ことが示された｡`次に,相関が高い条件は,室温20℃安静15分後に血流量を測定した場合(r=0.483,p=0.0002)であった｡そして温 水36℃浸水負荷10分後に測定して得られた結果とが最も相関関係が低い結果となった｡更に,冷水20℃浸水負荷30分後に測定して得られた結果を温水36℃浸水負荷10分後に測定して得られた結果で割った比を%で表示したところ回復率とこの比との間には正の相関関係(r=0.46,p<0.0001)が認められた｡このことから,温水36℃負荷時と,冷水20℃負荷時との差が大きい患者 において末梢皮膚温度の低下が著しいことが示された｡これまで悲観血的に測定されてきたサーモグラフィーによる末梢循環の数量的評価の試みは,レーザー血流計による結果と組み合わせることで,両者の間に正の相関関係が示されたことにより,今後,数量化された客観的評価を可能にした

Degradation assessment of industrial composites using thermography

Thermographic inspection is a relatively new technique for Non-Destructive Testing (NDT) which has been gathering increasing interest due to its relatively low cost hardware and extremely fast data acquisition properties. This technique is especially promising in the area of rapid automated damage detection and quantification. In collaboration with a major industry partner from the aerospace sector advanced thermography-based NDT software for impact damaged composites is introduced. The software is based on correlation analysis of time-temperature profiles in combination with an image enhancement process. The prototype software is aiming to a) better visualise the damages in a relatively easy-to-use way and b) automatically and quantitatively measure the properties of the degradation. Knowing that degradation properties play an important role in the identification of degradation types, tests and results on specimens which were artificially damaged have been performed and analyzed.EPSR