Automatic CT-based finite element model generation for temperature-based death time estimation: feasibility study and sensitivity analysis

AbstractTemperature-based death time estimation is based either on simple phenomenological models of corpse cooling or on detailed physical heat transfer models. The latter are much more complex but allow a higher accuracy of death time estimation, as in principle, all relevant cooling mechanisms can be taken into account.Here, a complete workflow for finite element-based cooling simulation is presented. The following steps are demonstrated on a CT phantom:Computer tomography (CT) scanSegmentation of the CT images for thermodynamically relevant features of individual geometries and compilation in a geometric computer-aided design (CAD) modelConversion of the segmentation result into a finite element (FE) simulation modelComputation of the model cooling curve (MOD)Calculation of the cooling time (CTE) For the first time in FE-based cooling time estimation, the steps from the CT image over segmentation to FE model generation are performed semi-automatically. The cooling time calculation results are compared to cooling measurements performed on the phantoms under controlled conditions. In this context, the method is validated using a CT phantom. Some of the phantoms’ thermodynamic material parameters had to be determined via independent experiments.Moreover, the impact of geometry and material parameter uncertainties on the estimated cooling time is investigated by a sensitivity analysis.

[1]  C. D. Robinson,et al.  Estimators of Tissue Proportions from X‐Ray CT Images , 2002, Biometrics.

[2]  Gita Mall,et al.  Estimation of time since death by heat-flow Finite-Element model. Part I: method, model, calibration and validation. , 2005, Legal medicine.

[3]  Z. Hong,et al.  Thermal Analysis of Four Insect Waxes Based on Differential Scanning Calorimetry (DSC) , 2011 .

[4]  M. Breed,et al.  The thermal properties of beeswaxes: unexpected findings , 2008, Journal of Experimental Biology.

[5]  Rolf Steinbuch Finite Elemente — Ein Einstieg , 1998 .

[6]  H. Boeing,et al.  Low-dose spiral computed tomography for measuring abdominal fat volume and distribution in a clinical setting , 1998, European Journal of Clinical Nutrition.

[7]  H. Handels Segmentierung medizinischer Bilddaten , 2009 .

[8]  Binsheng Zhao,et al.  Automated Quantification of Body Fat Distribution on Volumetric Computed Tomography , 2006, Journal of computer assisted tomography.

[9]  I. Babuska,et al.  GENERALIZED FINITE ELEMENT METHODS — MAIN IDEAS, RESULTS AND PERSPECTIVE , 2004 .

[10]  C. Kaüfer [Determination of the time of death]. , 1972, Fortschritte der Medizin.

[11]  E. W. Washburn,et al.  International Critical Tables of Numerical Data, Physics, Chemistry and Technology , 1926 .

[12]  Estimation of Time of Death With a Fourier Series Unsteady‐State Heat Transfer Model , 2010, Journal of forensic sciences.

[13]  Hans Rudolf Schwarz,et al.  Methode der finiten Elemente , 1984 .

[14]  E. Southwick Thermal conductivity of wax comb and its effect on heat balance in colonial honey bees (Apis mellifera L.) , 1985, Experientia.

[15]  Stefan Zachow,et al.  Adaptive Remeshing of Non-Manifold Surfaces , 2008, Eurographics.

[16]  J. Reddy An introduction to the finite element method , 1989 .

[17]  M J Pearcy,et al.  A new approach for assigning bone material properties from CT images into finite element models. , 2010, Journal of biomechanics.

[18]  P. Deuflhard,et al.  Numerische Mathematik 3 , 2011 .

[19]  Wolfgang Branscheid,et al.  Schlachtkörperwertbestimmung beim schwein röntgen- computertomographie als mögliche referenzmethode , 2004 .

[20]  G. Höhne,et al.  Theoretical Fundamentals of Differential Scanning Calorimeters , 2003 .

[21]  Hans-Christian Hege,et al.  amira: A Highly Interactive System for Visual Data Analysis , 2005, The Visualization Handbook.

[22]  S. Medved,et al.  Influence of accuracy of thermal property data of a phase change material on the result of a numerical model of a packed bed latent heat storage with spheres , 2005 .

[23]  P. Allen,et al.  Development of a computed tomographic calibration method for the determination of lean meat content in pig carcasses. , 2006, Acta veterinaria Hungarica.

[24]  F. Duck Physical properties of tissue , 1990 .

[25]  Noriyuki Moriyama,et al.  Development of an automated 3D segmentation program for volume quantification of body fat distribution using CT. , 2008, Nihon Hoshasen Gijutsu Gakkai zasshi.

[26]  J. Clarys,et al.  Post-mortem limitations of body composition analysis by computed tomography. , 1994, Ergonomics.

[27]  G. Timbers,et al.  Thermal Properties of Beeswax and Beeswax-Paraffin Mixtures , 1977 .

[28]  Young Jae Kim,et al.  Body Fat Assessment Method Using CT Images with Separation Mask Algorithm , 2013, Journal of Digital Imaging.

[29]  Geoffrey McLennan,et al.  CT-based geometry analysis and finite element models of the human and ovine bronchial tree. , 2004, Journal of applied physiology.

[30]  James S Babb,et al.  Multi-detector row CT attenuation measurements: assessment of intra- and interscanner variability with an anthropomorphic body CT phantom. , 2007, Radiology.

[31]  Hans-Christian Hege,et al.  3D Reconstruction of Individual Anatomy from Medical Image Data: Segmentation and Geometry Processing , 2007 .

[32]  N. N. Mohsenin,et al.  Thermal Properties of Food and Agricultural Materials , 1980 .

[33]  C Henssge,et al.  Death time estimation in case work. I. The rectal temperature time of death nomogram. , 1988, Forensic science international.

[34]  Ioannis A. Kakadiaris,et al.  Automatic Segmentation of Abdominal Fat from CT Data , 2005, 2005 Seventh IEEE Workshops on Applications of Computer Vision (WACV/MOTION'05) - Volume 1.

[35]  J. P. Clarys,et al.  Cadaver studies and their impact on the understanding of human adiposity , 2005, Ergonomics.

[36]  Peter Deuflhard,et al.  Mathematical Cancer Therapy Planning in Deep Regional Hyperthermia 1 , 2011 .

[37]  Kozo Nakamura,et al.  The “Intrinsic” Thermal Conductivity of Some Wet Proteins in Relation to Their Hydrophobicity: Analysis on Gelatin Gel , 1982 .

[38]  J. Z. Zhu,et al.  The finite element method , 1977 .

[39]  P. Deuflhard,et al.  Adaptive Lösung partieller Differentialgleichungen , 2011 .

[40]  Davide G. Tommasi,et al.  Age- and sex-related changes in the normal human ear. , 2009, Forensic science international.

[41]  Sebastian Götschel,et al.  Solving Optimal Control Problems with the Kaskade 7 Finite Element Toolbox , 2012 .

[42]  Gita Mall,et al.  Estimation of time since death by heat-flow Finite-Element model part II: application to non-standard cooling conditions and preliminary results in practical casework. , 2005, Legal medicine.