Less-experienced Operators Research Articles

Comparison of 3D-Printed Single Crown Outcomes Among Different Computer-Aided Design Software Programs.

Low-cost resin 3D printers have been used to produce affordable interim single crowns in public and private dental practices. The purpose of this study was to assess the impact of different computer-aided design (CAD) software programs on 3D trueness, microscopic marginal and internal gaps, time to design, and interproximal contacts of low-cost 3D-printed single crowns. This in vitro study was performed on a total of 90 standardized resin-prepared teeth adapted to a dental manikin. For comparison among CAD software programs, 45 tooth preparations received 3D-printed crowns designed with one of three CAD software programs by an experienced technician and identified as groups TRIOS (n = 15), EXOCAD (n = 15), and ZZ (Zirkonzahn; n = 15). To assess interoperator reproducibility, 15 additional crowns were designed by a dental clinician (group ZZ-DENT) and 15 by a dental prosthetic technician (group ZZ-PROS), both with basic 1-week CAD/CAM training. Finally, as a control group, 15 crowns were milled using a high-end five-axis milling device (group ZZ-CONTROL). Statistically significant differences for 3D trueness, microscopic gaps, time to design, and interproximal contacts among groups were assessed with the Kruskal-Wallis test. No statistically significant differences in 3D trueness or marginal or internal gaps were found, either among different software programs or CAD operators (P > .05). However, Group TRIOS took significantly longer to design than EXOCAD and ZZ groups (P = .001). Less-experienced operators were significantly outperformed in time and interproximal contacts (P = .001) by the CAD technician using the same software program. Finally, control milled crowns (ZZ-CONTROL) significantly outperformed the respective 3D-printed copies (ZZ) in all assessed variables (P < .001). Different CAD software programs may affect the time required to design, but they do not significantly affect clinical outcomes of low-cost 3D-printed resin crowns if designed by an experienced CAD technician.

Real-time guidance by deep learning of experienced operators to improve the standardization of echocardiographic acquisitions.

Impaired standardization of echocardiograms may increase inter-operator variability. This study aimed to determine whether the real-time guidance of experienced sonographers by deep learning (DL) could improve the standardization of apical recordings. Patients (n = 88) in sinus rhythm referred for echocardiography were included. All participants underwent three examinations, whereof two were performed by sonographers and the third by cardiologists. In the first study period (Period 1), the sonographers were instructed to provide echocardiograms for the analyses of the left ventricular function. Subsequently, after brief training, the DL guidance was used in Period 2 by the sonographer performing the second examination. View standardization was quantified retrospectively by a human expert as the primary endpoint and the DL algorithm as the secondary endpoint. All recordings were scored in rotation and tilt both separately and combined and were categorized as standardized or non-standardized. Sonographers using DL guidance had more standardized acquisitions for the combination of rotation and tilt than sonographers without guidance in both periods (all P ≤ 0.05) when evaluated by the human expert and DL [except for the apical two-chamber (A2C) view by DL evaluation]. When rotation and tilt were analysed individually, A2C and apical long-axis rotation and A2C tilt were significantly improved, and the others were numerically improved when evaluated by the echocardiography expert. Furthermore, all, except for A2C rotation, were significantly improved when evaluated by DL (P < 0.01). Real-time guidance by DL improved the standardization of echocardiographic acquisitions by experienced sonographers. Future studies should evaluate the impact with respect to variability of measurements and when used by less-experienced operators. NCT04580095.

Clinical performance of CAD-CAM partial-coverage restorations: Experienced versus less-experienced operators

Statement of problemLess-experienced operators have been shown to require additional training to achieve results similar to those of experienced operators. However, clinical data comparing the survival and success of ceramic restorations by experienced and less-experienced operators by using the computer-aided design and computer-aided manufacturing (CAD-CAM) technology are lacking. PurposeThe purpose of this retrospective clinical study was to analyze and compare the clinical performance of CAD-CAM lithium disilicate restorations fabricated by less-experienced (predoctoral dental students) and experienced (dentists) operators. Material and methodsPatients who received an adhesively luted CAD-CAM lithium disilicate restoration between 2011 and 2019 were included in the study. Clinical performance was assessed by calibrated examiners by using World Dental Federation (FDI) criteria. Success and survival were calculated by the Kaplan-Meier method and statistically compared by log-rank tests and univariate Cox regression analyses. FDI criteria were compared by using Mann-Whitney-U tests (α=.05). ResultsNinety-two restorations (students: n=65, dentists: n=27) were assessed (mean ±standard deviation time from insertion: 4.04 ±1.55 years). The survival rates after 2 years (students: 93.8%, mean annual failure rate [mAFR]: 3.1%; dentist: 96.3%, mAFR: 1.9%) and after 4 years (students: 87.3%, mAFR: 3.3%; dentists: 88.3%, mAFR: 3.1%) were not significantly different (P=.525). Also, success rates after 2 (students: 90.8%, mAFR: 4.7%; dentists: 92.6%, mAFR: 3.8%) and 4 years (students: 82.4%, mAFR: 4.7%; dentists: 76.1%, mAFR: 6.6%) were not significantly different (P=.778). FDI criteria were also not significantly different between less-experienced and experienced operators (P≥.110). ConclusionsOperator experience did not affect the short-term clinical performance of CAD-CAM lithium disilicate restorations.

Improvement of diagnostic efficiency in fetal congenital heart disease using fetal intelligent navigation echocardiography by less-experienced operators.

This study investigated the feasibility and accuracy of fetal intelligent navigation echocardiography (FINE) for the prenatal diagnosis of congenital heart disease (CHD) by inexperienced and experienced operators. In this prospective study, all volume data sets from 120 fetuses with a broad spectrum of CHD were acquired using spatiotemporal image correlation technology. The prenatal diagnostic procedures were performed by two operators with different experience (beginner: 1year and expert: 15 years) using FINE and traditional fetal echocardiography. Data were analyzed on the time of examination and acquisition of results. Diagnoses made by FINE and traditional echocardiography were completely consistent with the final diagnosis of CHD in 98 (81.66%) versus 20 (16.66%) (P< 0.001) beginners and 87.50% (n= 105) versus 101 (84.16%) experts, respectively. On the contrary, there was significant difference using traditional echocardiography (16.66% versus 84.16%, P< 0.001) by two examiners. Furthermore, the examination time decreased when using FINE compared with using traditional echocardiography (beginner operators: 4.54 ± 1.03 min versus 20.58 ± 3.36 min, P< 0.001; expert operators: 3.89 ± 0.96 min versus 12.73 ± 1.62 min, P< 0.001). Based on our results, a prenatal diagnosis of CHD can be made with high feasibility and accuracy using FINE compared with traditional fetal echocardiography for beginner operators.

A Hybrid Robust-Learning Architecture for Medical Image Segmentation with Noisy Labels

Deep-learning models require large amounts of accurately labeled data. However, for medical image segmentation, high-quality labels rely on expert experience, and less-experienced operators provide noisy labels. How one might mitigate the negative effects caused by noisy labels for 3D medical image segmentation has not been fully investigated. In this paper, our purpose is to propose a novel hybrid robust-learning architecture to combat noisy labels for 3D medical image segmentation. Our method consists of three components. First, we focus on the noisy annotations of slices and propose a slice-level label-quality awareness method, which automatically generates label-quality scores for slices in a set. Second, we propose a shape-awareness regularization loss based on distance transform maps to introduce prior shape information and provide extra performance gains. Third, based on a re-weighting strategy, we propose an end-to-end hybrid robust-learning architecture to weaken the negative effects caused by noisy labels. Extensive experiments are performed on two representative datasets (i.e., liver segmentation and multi-organ segmentation). Our hybrid noise-robust architecture has shown competitive performance, compared to other methods. Ablation studies also demonstrate the effectiveness of slice-level label-quality awareness and a shape-awareness regularization loss for combating noisy labels.

Accuracy of an electrical impedance device in estimation of remaining dentin thickness vs cone beam computed tomography.

The objective of this study is to compare the estimated values of remaining dentin thickness (RDT) recorded by a newly introduced electrical impedance device (Prepometer) with cone beam computed tomography (CBCT) and histological in situ measurement. A total number of thirty human molars were used in this study. A deep class I cavity was prepared. The RDT for each cavity was measured with Prepometer in three different points (mesial, middle, and distal). Same specimens were imaged with high-resolution Cone Beam Computed Tomography CBCT (0.1mm voxel size) using I CAT next Generation Machine (Imaging Science International, Hatfield, PA, USA), to provide the highest possible accuracy of linear measurements. Finally, the specimens were vertically sectioned parallel to the long axis of the tooth in a mesiodistal direction splitting the cavity into two halves through its center. Then, the actual RDT of each half will be measured in the same three points using a digital caliper. The outcome of one-way ANOVA revealed that there was no significant difference in RDT values measured by prepometer device, CBCT, or histological sectioning methods (p > 0.05). Within the limitations of this laboratory study, prepometer seems to be a potential non-invasive accurate measuring tool for RDT. Based on the findings of this study, the Prepometer can be considered as an easily handled and less-expensive method compared to CBCT to evaluate the RDT. Also, it can be used in dental schools and with less-experienced operators to avoid traumatic exposures of the dental pulp.

Technical feasibility and efficacy of a standard needle magnetization system for ultrasound needle guidance in thyroid nodule-targeting punctures: a phantom study.

PurposeThe aim of this study was to assess the feasibility and efficacy of an ultrasound needle guidance system (NGS) based on standard needle magnetization in a phantom study of thyroid nodule (TN)-targeting punctures.MethodsSix trainees and a staff radiologist performed TN-targeting punctures with or without the NGS in phantom models (group 1, experience <50 cases; group 2, experience ≥50 cases and <100 cases; group 3, experience ≥100 cases of TN-targeting punctures). The feasibility, technical success rate, number of punctures, and procedure time were recorded.ResultsThe feasibility of NGS was 98.6% (138/140). In group 1, the technical success rate increased from 60.0%±8.2% to 80.0%±8.2% when the NGS was used (P=0.046), with a reduction in the number of punctures from 2.2 to 1.2 (P=0.005). In group 2, the rate changed from 95.0%±5.8% to 100.0%±0.0% with the NGS (P=0.157), with a minimal decrease in the number of punctures from 1.1 to 1.0 (P=0.157). The procedure time significantly decreased in both groups (P=0.041 and P=0.010, respectively) when the NGS was used. In group 3, there were no significant differences in the technical success rate and the number of punctures according to whether the NGS was used (P=0.317 and P=0.317, respectively).ConclusionNGS using standard needle magnetization is technically feasible and has potential to improve the efficacy of TN-targeting punctures for less-experienced operators, especially beginners, according to the findings of this phantom study.

Ultrasound-guided arterial cannulation or by pulse palpation in the intensive care unit

IntroductionUltrasound (US) guidance increases the success rate and decreases complications during central venous catheterisation (CVC). The benefits of US guidance in arterial catheterisation are less clear. The aim of this study is to compare the outcomes of US-guided arterial catheterisation with the traditional landmark (LM) technique in critically ill children. MethodsA prospective multicentre study was carried out in 18 Paediatric Intensive Care units in Spain during a 6-months period. Ultrasound guided and landmark techniques were compared in terms of cannulation technical success and immediate mechanical complications. ResultsA total of 161 procedures were performed on 128 patients (78 procedures in the US group and 83 in the LM groups).. The median (interquartile range) age and weight of the cohort was 11 months (2–52), and 10 kg (4–17) respectively. More than half (59.6%) were male. US was used mainly in high-volume-high-complexity hospitals (cardiac surgery program 76.9% vs. 25.6%, P < .001) as well as in smaller children [weight 5.7 kg (3.8−13) vs 11.5 kg (4.9−22.7), P < .001]. Almost half (49.7%) of the procedures were performed by an inexperienced operator (paediatric resident, or staff with less than 5 years of clinical experience in the PICU), and only 24.4% had performed more than 50 US-guided vascular access procedures before the study. There were no significant differences between US and LM techniques in terms of first-attempt success (35.8% vs 33.7%, P = .773), overall success (75.6% vs 71.1%, P = .514), number of puncture attempts [2 (1−4) vs 2 (1−3), P = .667] and complications (16.6% vs 25.6%, P = .243). Adjustment by potential confounders using multivariate regression models did not modify these results. Subgroup analyses showed that US outperformed LM technique in terms of overall success (83.7% vs 62.7%, P = .036) and complications (10.8% vs 32.5%, P = .020) only when procedures where performed by less-experienced operators. ConclusionsIn this prospective observational multicentre study, US did not improve arterial cannulation outcomes compared to the traditional LM technique in critically ill children. US-guided arterial cannulation may offer advantages when cannulation is performed by inexperienced operators.

Sonographic Differential Diagnosis in Deep Infiltrating Endometriosis: The Bowel.

Up to one-third of fertile-age women with severe endometriosis suffer from colonic involvement. Transvaginal ultrasonography has become a first-line diagnostic tool for the study of the pelvis and more specifically for the diagnosis of pelvic endometriosis. Accuracy of pelvic ultrasound for deep endometriosis increases with operator experience, but the difficulties in the differential diagnosis with diseases that can afflict the bowel tract remain a challenge. We reviewed noteworthy cases referred for secondary level diagnosis suspected of bowel endometriosis in which the subsequent ultrasound led to an alternative diagnosis. This case series aims to highlight awareness for both experts and less-experienced operators the possible differential diagnoses of bowel lesions that initially resemble endometriosis.

PERCUTANEOUS CT-GUIDED CORE BIOPSY OF THE LUNG: IS THERE ANY BENEFIT FROM USING INTRAPARENCHYMAL BLOOD PATCHING?

SESSION TITLE: Tuesday Abstract Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM PURPOSE: To assess the effect of intraparenchymal blood patching (IBP) as well as tumor- and operator-related risk factors on the rate of pneumothoraces after percutaneous CT-guided core needle biopsy of the lung. METHODS: Following institutional review board approval, we performed a retrospective analysis of 868 CT-guided lung biopsies that were performed at our institution between 2003 and 2018, of which 419 (48%) received an IPB. Outcome variable included the rates of pneumothorax and chest tube placement, as well as lesion size (< 3 cm versus ≥ 3 cm long axis diameter), lesion depth (< 2 cm, < 4 cm, < 5 cm and > 5 cm distance to the pleura), location within the lungs, needle caliber, number of samples taken (1-3 versus ≥ 4 samples), and experience of the performing physician. RESULTS: The rate of pneumothorax was significantly (p < 0.05) lower in the group with IPB (10.7%) compared to the group without IPB (15.4%). The number of post-interventional chest tube placements differed also between the groups with IPB (3.1%) vs. non-IPB (5.8%). The lesion size correlated negatively with the rate of pneumothoraces, whereas in both groups (±IBP) lesions > 3 cm showed a significantly lower rate of pneumothorax (p < 0.05). With increasing lesion depth the pneumothorax rate increased with (p < 0.001) and without (p < 0.001) IPB. The rate of pneumothorax was significantly lower (p < 0.05) for 17G needles with IPB, but not for other calibers. For biopsies in the lower lobe, the pneumothorax rate reduced significantly (p < 0.001) with IPB. The rate of pneumothorax differed from 11.1% with IPB to 24.8% without IPB only for less experienced operators. In case of > 3 tissue samples, the pneumothorax rate was significantly lower with IPB (p < 0.01). CONCLUSIONS: IPB significantly reduces the rate of pneumothorax following CT-guided lung biopsies in particular for lesions located deeper in the lungs, when more than 3 samples are taken, when samples are taken by less-experienced operators, and when sampling from the lower lobes. CLINICAL IMPLICATIONS: IPB reduces the risk of pneumthoracs of CT-guided percutanous biopsies. DISCLOSURES: Workshop and Pesentation relationship with Erbe, Medizintechnik GmbH, Tuebingen, Germany Please note: $1-$1000 Added 01/07/2019 by Juergen Hetzel, source=Web Response, value=Honoraria No relevant relationships by Marius Horger, source=Web Response No relevant relationships by Regine Mariette Perl, source=Web Response no disclosure on file for Werner Spengler

The effect of intraparenchymal blood patching on the rate of pneumothorax in patients undergoing percutaneous CT-guided core biopsy of the lung

PurposeTo assess the effect of intraparenchymal blood patching (IBP) as well as tumor- and operator-related risk factors on the rate of pneumothoraxes after percutaneous CT-guided core needle biopsy of the lung. Materials and methodsWe performed a retrospective analysis of 868 CT-guided lung biopsies that were conducted at our institution between 2003 and 2018, of which 419 (48%) received an IBP. Outcome variable included the rates of pneumothorax and chest tube placement, as well as lesion size (<3 cm versus ≥3 cm long axis diameter), lesion depth (≤2 cm, >2-4 cm, >4-5 cm and >5 cm distance to the pleura), location within the lungs (upper lobe, lower lobe, middle lobe), needle caliber (13 G, 15 G, 17 G, 19 G), number of samples taken (1–3 versus ≥4 samples), and experience of the performing physician. ResultsThe rate of pneumothorax was significantly (p < 0.05) lower in the group with IBP (10.7%) compared to the group without IBP (15.4%). The number of post-interventional chest tube placements was also lower in the IBP group (3.1% vs. 5.8%) but not statistically significant. The lesion size correlated negatively with the rate of pneumothoraxes, whereas in both groups (±IBP) lesions ≥ 3 cm showed a significantly lower rate of pneumothorax (p < 0.05). With increasing lesion depth, the pneumothorax rate increased with (p < 0.01) and without (p < 0.001) IBP. The rate of pneumothorax was significantly lower (p < 0.05) for 17 G needles with IBP, but not for other calibers. For biopsies in the lower lobe, the pneumothorax rate reduced significantly (p < 0.001) with IBP. In case of ≥4 tissue samples, the pneumothorax rate was significantly lower with IBP (p < 0.01). For experienced operators, the overall pneumothorax rate was significantly lower compared to less experienced operators (p < 0001). ConclusionsIBP significantly reduces the rate of pneumothorax following CT-guided lung biopsies in particular for lesions located deeper in the lungs, when ≥4 samples are taken, when samples are taken by less-experienced operators, and when sampling from the lower lobes.

Advanced ultrasound for prenatal interventions.

Ultrasound is an integral part of prenatal interventions. Doppler studies and 3-dimensional ultrasound (3DUS) are frequently used to determine whether fetal surgery is required. The operator’s experience remains crucial for reducing procedure-related morbidity. Real-time 3DUS (or 4DUS) can simultaneously display the needle tip in three orthogonal planes, providing reassurance that no fetal parts are in the path. In experienced hands, 4DUS guidance may not be more effective than B-mode, but its value for less-experienced operators remains to be determined. Recent developments in needle, shunt, and video endoscopic technologies may compliment the use of image-guided in utero procedures. Future developments of higher-dimensional transducers and image software may improve the utility of ultrasound for invasive obstetric interventions.

Evaluating Novel Diagnostics in an Outbreak Setting: Lessons Learned from Ebola.

Inadequate access to rapid testing for Ebola virus disease during the 2014-to-2016 outbreak led to an explosion in the development of diagnostics that could be performed at or near the point of care and by less-experienced operators, leading in turn to an acute need for novel test evaluation. Here, we present the challenges to development and evaluation of novel diagnostics in an emergency setting and suggestions for potential new "global emergency standards" to address them.

Removal of simulated biofilm: an evaluation of the effect on root surfaces roughness after scaling.

Despite the development of less invasive devices, a debate exists about the benefits and risks of hand versus powered root surface instrumentation used in supportive periodontal therapy (SPT). The aim of the in vitro study was to differentially compare plaque removal efficacy and root surface roughening of newly developed sonic, ultrasonic scaler, and curettes in the hands of experienced versus less experienced operators. Sonic (AIR), ultrasonic devices (TIG), and double-gracey curettes (GRA) were utilized by seven experienced (EO) and four less experienced operators (LO) for root surface instrumentation of standardized plastic teeth on manikins' heads in a randomized sequence. The proportion of residual simulated plaque (RSP area in %) was planimetrically assessed, and the average root surface roughness produced (Ra and ∆Ra in μm) was measured by a precision profilometer. The uninstrumented root surfaces showed a Ra of (median (Q25/Q75)) 1.00μm (0.83/1.16). Following instrumentation, EO left significantly less RSP than LO regardless of the used instruments (20.00% (10.00/34.00) vs. 26.00% (12.00/44.00) p < 0.001), whereas the ∆Ra values (0.29μm (-0.04/0.96) vs. 0.35μm (-0.04/1.01), p = 0.237) failed to show significant differences. The surface roughness was higher with GRA followed by AIR then TIG regardless of operators' experience (p < 0.001). Within the limits of the present study, the sonic device was most efficient in plaque removal, while the ultrasonic device produced the least surface roughness. All three tested instruments seem effective in the mechanical root debridement during SPT, whereat the ultrasonic device show the smoothest root surface of all.

Removal of simulated biofilm: a preclinical ergonomic comparison of instruments and operators.

Periodontal scaling might cause musculoskeletal disorders, and scaling instruments might not only have different effectiveness and efficiency but also differ in their ergonomic properties. The present study assessed ergonomic working patterns of experienced (EO) and less experienced operators (LO) when using hand and powered devices for periodontal scaling and root planning. In an experimental study using periodontally affected manikins, sonic (AIR), ultrasonic (TIG) and hand instruments (GRA) were used by 11 operators (7 EO/4 LO) during simulated supportive periodontal therapy. Using an electronic motion monitoring system, we objectively assessed the working frequency and positioning of hand, neck and head. Operators' subjective evaluation of the instruments was recorded using a questionnaire. Hand instruments were used with the lowest frequency (2.57 ± 1.08s(-1)) but greatest wrist deviation (59.57 ± 53.94°). EO used instruments more specifically than LO, and generally worked more ergonomically, with less inclination of head and neck in both the frontal and sagittal planes, especially when using hand instruments. All groups found hand instruments more tiring and difficult to use than powered instruments. Regardless of operators' experience, powered instruments were used more ergonomically and were subjectively preferred compared to hand instruments. The use of hand instruments has potential ergonomic disadvantages. However, with increasing experience, operators are able to recognise and mitigate possible risks.

Subgingival instrumentation to remove simulated plaque in vitro: influence of operators’ experience and type of instrument

There is uncertainty regarding the benefits and risks of hand versus powered root surface instrumentation. Moreover, the influence of operators' experience on treatment results is unclear. We compared newly developed sonic, ultrasonic and hand instruments, hypothesizing that powered devices allow to remove more simulated plaque in less time than hand instruments, with significant influence of operators' experience. Sonic scaler (AIR), ultrasonic scaler (TIG) device and double Gracey curettes (GRA) were utilized by seven experienced operators (EOs) and four less experienced operators (LOs) in periodontitis manikin heads. The time required for treatment, the proportion of residual-simulated plaque and the weight loss caused by scaling as a proxy for root surface destruction were measured. Using different instruments led to significantly different proportions of removed simulated plaque regardless of operators' experience (AIR, 80.2 ± 21.3 %, TIG, 69.9 ± 22.5 %, GRA, 73.1 ± 20.0 %) (p < 0.001). Treatment times did not significantly differ between EO and LO (p > 0.05). Weight loss was increased when using hand instead of powered instruments (p < 0.001), with significantly higher weight loss induced by LO than EO (p = 0.004). Within the present study, EO did not remove more simulated plaque in less time but induced less root surface destruction. Using a sonic device was most beneficial for plaque removal. Successful root surface debridement requires both time and training regardless of the used instrument. Hand instruments might cause more damage to root surfaces, especially in the hands of less experienced operators.

Dilator method and needle method for atrial transseptal puncture: a retrospective study from a cohort of 4443 patients

To compare the safety and efficacy of a new dilator method vs the traditional needle method for transseptal puncture (TSP) in a large cohort study. From February 1995 to December 2010, 4443 consecutive patients undergoing TSP done either by a needle method or by a new dilator method were reviewed retrospectively. Data as procedure-related time and complications were evaluated. For the standard needle method, TSP was performed by extending out the needle. In comparison, for the new dilator technique, TSP was performed without an outer sheath and with the needle kept within the dilator; the blunt tip of the dilator was used to help locating the position of the fossa ovalis on purpose. Transseptal puncture was performed by the new dilator method in 2151 patients (48.4%) and by the traditional needle method in 2292 patients (51.6%). The average TSP time needed by the dilator method was longer than that needed by the needle method (5.6 ± 3.9 vs. 3.8 ± 2.9 min, P< 0.05). Additional left atrial angiography was required in seven (0.33%) patients for the dilator and in 39 patients (1.70%) for the needle method (P< 0.05). The total rate of severe complications and obvious TSP-related complications was significantly lower in patients who underwent the dilator method than in those who underwent the needle method (0.33 vs. 1.18%, and 0.20 vs. 1.00%, respectively, P < 0.05). Our data suggest that the new dilator technique is much safer than that of the standard needle method. It needs relatively longer procedure time but results in significantly fewer episodes of severe complications. Particularly, the blunt tip of the dilator can be used to help locate the fossa ovalis. Therefore, the new dilator technique might be a better choice for relatively less-experienced operators.

Can reduced processing decision support interfaces improve the decision-making of less-experienced incident commanders?

Computer-based decision support systems have been proposed as a tool to improve the decision-making of less-experienced personnel by reducing the information processing demands necessary for decision-making. This study investigated the utility of three decision support system interfaces that differed in their capacity for reduced processing. The participants comprised experienced and less-experienced Fireground Incident Commanders who used the decision support system interfaces to identify the most appropriate entry point to extract a victim from a simulated burning building. The results revealed that reduced processing interfaces enabled less-experienced participants to acquire information using a process equivalent to their more experienced counterparts. However, this process did not result in improvements in the accuracy of the decision-making process. Indeed, the accuracy of experienced participants' decisions was consistently greater than the less-experienced participants, irrespective of the decision support system interface. It was concluded that the success of reduced processing decision support systems amongst less-experienced operators is significantly dependent upon their understanding of the relative value of key features associated with the decision-making process.

Mathematical Modeling of Thermal Ablation

Ablation techniques have become a widespread choice for the treatment of cancerous tumors for which surgical resection techniques have a poor prognosis. The minimally invasive nature and high success rate when performed by experienced clinicians mean that ablation is likely to remain a core technique. However, the success rate can drop off dramatically when less-experienced operators are involved, and it is particularly difficult to kill all of the tumor and only the tumor, given the dynamic nature of the processes that lead to cell death. Mathematical modeling of the response to ablation treatment has a long history. Since the seminal paper of Pennes in 1948, there have been numerous attempts to propose models that are both physiologically accurate and computationally inexpensive. All of these models are based on different principles and assumptions, which may make them suitable only for particular applications. This makes choosing a model very difficult because of the lack of understanding about what the limitations of different assumptions are likely to be and how this influences the necessary computational resources. Here we review the models available in the literature, illustrating how the different assumptions impact upon both their accuracy and computational expense.The primary intentions are to provide a critical scientific review and a practical guide for researchers wishing to use such models in clinical applications.

Operator strategies in a dynamic environment in relation to an operator model

Results of an analysis of the cognitive activity of operators in controlling incidents in a Steam Generating Heavy Water Reactor in relation to a computer-based model of an operator (COSIMO, Cacciabue et al. 1992) are presented. The analysis focuses on information checking and actions to be taken in five incidents of varying levels of specification. Two experienced and two less-experienced operators participated in the experiments. Techniques of video and protocol analysis have been employed. Results indicate that operators use strategies in order to overcome the dynamic feature of incidents; in particular they break down problems into elementary problems, and they aim at maintaining a stable situation. A central characteristic is the importance of actions in terms of their timing and their results. Actions are carried out incrementally, and their effects then used as pointers to guide the course of future problem-solving and future actions. Problems may be postponed when they are not urgent, or when system latency does not allow an effect to be obtained following an action. Finally the paper discusses some elements that should be modified in order to increase the predictive capability of the COSIMO model.