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Temperature monitoring during RF ablation has been proposed as a means of controlling the creation of the lesion. However, in vivo studies have shown poor correlation between lesion size and catheter tip temperature. Thus, we hypothesized a difference between catheter tip and tissue temperatures during RF catheter ablation, and that this difference may depend on flow passing the ablation site, tip electrode length, and catheter-tissue orientation. In vitro studies were performed using four different ablation catheters (tip electrode length: 2, 4, or 6 mm) with a thermistor or a thermocouple as temperature sensor. Set temperature was 70 degrees C and pulse duration was 30 seconds. Pieces of porcine left ventricle were immersed in a bath of isotonic saline-dextrose solution at 37 degrees C. The ablation catheters were positioned perpendicularly, obliquely, or parallel to the endocardium. A temperature sensor was inserted from the epicardial side and positioned 1 mm beneath the catheter-tissue interface. Experiments were made with a flow of 200 mL/min passing the ablation site or with no flow. The catheter tip and tissue temperatures differed significantly (P < 0.0001) during ablation. This difference increased with time, with flow passing the ablation site, with the length of the tip electrode, and when the catheter was positioned perpendicularly or obliquely to the endocardium as compared to the parallel catheter-tissue orientation (P < 0.05). In conclusion, the tissue temperature may far exceed the catheter tip temperature, and intramyocardial superheating resulting in steam formation and popping may occur despite a relatively low catheter tip temperature.

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Engineering has been playing an important role in serving and advancing healthcare. The term "Healthcare Engineering" has been used by professional societies, universities, scientific authors, and the healthcare industry for decades. However, the definition of "Healthcare Engineering" remains ambiguous. The purpose of this position paper is to present a definition of Healthcare Engineering as an academic discipline, an area of research, a field of specialty, and a profession. Healthcare Engineering is defined in terms of what it is, who performs it, where it is performed, and how it is performed, including its purpose, scope, topics, synergy, education/training, contributions, and prospects.Keywords: Healthcare engineering, definition, purpose, scope, topics, synergy, jobs, education, training, contributions, future PREAMBLEEngineering has been playing a crucial role in serving healthcare, bringing about revolutionary advances in healthcare. Contributions have been made by engineers from almost all engineering disciplines, such as Biomedical, Chemical, Civil, Computer, Electrical, Environmental, Industrial, Information, Materials, Mechanical, Software, and Systems Engineering, as well as healthcare professionals such as physicians, dentists, nurses, pharmacists, allied health professionals, and health scientists who are engaged in supporting, improving, and/or advancing any aspect of healthcare through engineering approaches. "Healthcare Engineering" is the most appropriate term to encompass such a multi-disciplinary specialty, considering that advancing healthcare is the common goal for all such efforts made through engineering approaches. However, so far, a clear, rigorous definition of "Healthcare Engineering" has never been documented.Established over 50 years ago, the American Society of Healthcare Engineering (ASHE) [1] was one of the first to publicize the term "Healthcare Engineering". ASHE, as well as its many local affiliate societies (e.g., [2]), has been mainly dedicated to the health care physical environment, which represents only one sector of what engineers do in healthcare. David and Goodman [3] first used the term "healthcare engineers" in the scientific literature in 1989, where the critical role of the engineer in the healthcare delivery system was discussed. A number of academic programs have adopted the term "Healthcare Engineering" in their names (e.g., [4][5][6][7][8][9][10][11][12][13]). However, the description/definition of "Healthcare Engineering" by these programs varies, as each institution has designed its program based on its own distinctive interest, strength, focus, and emphasis, and hence created a different description/definition accordingly. Each of these versions of description/definition excellently portrays a certain facet of Healthcare Engineering, though none reflects all dimensions of the discipline. Further, the Journal of Healthcare Engineering [14], launched in 2010, focuses on engineering involved in all aspects of healthcare delivery processes and systems....

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htcrnet: l~ttI)://www.tclc.nuc.dklt.isc/.Ahrmci-Ttib pnper prrscnts R neiv tcsl lixturc with assnclnturl [ICentbcdding proccdurc for elYccicnt and nccurstc rrii-wnfer dcvicc iiicasurciticm$ at micmwave frcqucncies. 'rho fixtiarc is Ii~wrl un a siihs~ratc slilcld snd (i) pmvldcs sn xcuratc cnninion Erourid for N-port measurcnnentr, (ii) cffcctivcly rcdnccs suhstmic cnrricrl coupling, (iii) fiivrs wcll-dcfiiicd parasitics for slnipliflcd de-cnilwldiiig, and (lv) fits mliitrnrlly large devicw. DUC tu tliesc clinrricteridics, the accompnnying dc~cmhcddiiig tcchiiiquc rcqiiircs only few in-lxtarc stand:irtls tfint can he fahricatcd with vcry high accuracy; evcn iin standard CMOS prii-CCSSES. The tcclinlquc can :idva1it~gc01~~1~ 1)c nppllod to a witlo rmac nf conuiioiily uscd processes, but Iiighcst perforinnnce iitqirnvcnicnt is :ichicved with low-rcsiativity suhslratcs. Tlic pcrhnioncc OF Ihe tcrlinlyuc is dcmoiistratcd In 12GHfi in a 0.25pni CMWi kctinulogy mid ciiii. clrisions arc drawn. I. INTKODIJCl'IONOR low-cost silicon CMOS tecl~n~iogy to bccolnc a suc-F ccssM RF-IC contcndcr, accurm and rclinhlc rlevicc inotlcls inus1 hc contrivcd. Howcvcr, accuralc inodeting calls for precisc on-wafer tneasurcniciits that wc htirrl to obiitin due to liigti substrate losscs atid low inlcrconnccl ctinductnncc inherent to CMOS technology [I]. For o w , it iinplics [hat calibration with a ceramic impedalnnca stcdard sr!bumrte (ISS)is not sufficient ror establishing a rcfercnco plane closc to the device under test (DUT) (21. As sufficiently prccise onwafer standards are not currciitly availablc it) standard CMOS technology for accuratc two-port TRL cdibration, various deembctldiiig tecliniqtics arc oftcn npplicd in conjunctioii with TSS celibratioii [3j, [4], [ 5 ] . As atldrcsscd in 161, accurate tlecinbcrlding rcquircs that the tcst fixture displays a few cnsily idcnti hcd and dorni nating pamsitics.In this paper a tcsi 6xturc design is prescntcd that effcclively provides a stiicld for mitigating rhc effcct or substraic parasitics. This makes thc fixture pnrticularly iiscfiil for silicon CMOS technology, but also Cor 0 t h intcgrated proccsses with higher suhstrate resistivity. By utilizing the groutitlshielded mcasuring tectiniqiic, and thercby rcducitig substrate efl'ccts, negligible I'orwarrl coupling i s echievcd which inakcs ihc mctliod scalahlc and very cost-cfficient. The fixturc is generally applicable to N-port measuretucnts and firs arbitrarily sized dcviccs such as transistors, inductors, and capacitors. 111 this p a p , however, only iwo-port meiisurcincnts are considered. Bascd on a detailed study of fixture parasitics, n tleembedding approach is proposed that eludes ovcr-calibration dtic to imperfect standards. Recnusc of this ability, one gencric tcst-fixturc can be uscd to predict thc pcrforoinncc of 0 t h similar fixturcs which tiold arbitrarily sizctl deviccs. This is R great advantage for CMOS tectinnlogy whcrc devices d t c n occupy a largc area to compmsate For low devicc pcrformencc per m a . As shall he ...