Segmentectomy-oriented anatomical model for enhanced precision surgery of the left upper lobe.

Objective: To optimize surgical outcomes and minimize complications in complex segmentectomy of the left upper lobe, we investigated the topographical anatomy of the left upper lobe and developed a segmentectomy-oriented anatomical model. Methods: A state-of-the-art 3-dimensional computed tomography workstation was used to visualize the intersegmental planes and associated veins to categorize the anatomical patterns influencing surgical procedures during left upper lobe segmentectomy. This included the central vein affecting S1+2 (apicoposterior segment) segmentectomy, the transverse S3 (anterior segment) affecting S3 segmentectomy, and other venous branching patterns in 395 patients who underwent thoracic surgery at our institution. Results: The central vein was observed in 32% of the patients, necessitating access from the interlobar area after segmental artery and bronchus division. Transverse S3 incidence was 27%, revealing that only one-third of the patients required complete left upper lobe transection between S4 and S3 during S3 segmentectomy. A significant negative correlation was observed between the presence of transverse S3 and the central vein (<10% of patients with the central vein had transverse S3 and vice versa). In 6% of patients, the lingular segmental veins partially or entirely drained into the inferior pulmonary vein, potentially causing excessive or insufficient resection during surgery. Conclusions: This study offers valuable insights into the topographic anatomy of the left upper lobe and presents a segmentectomy-oriented anatomical model for complex segmentectomies. Our approach enables a more precise and individualized surgical planning for patients undergoing segmentectomy based on their unique anatomy, which could thereby lead to improved patient outcomes.

Dimensional accuracy and precision and surgeon perception of additively manufactured bone models: effect of manufacturing technology and part orientation.

BACKGROUND: Additively manufactured (AM) anatomical bone models are primarily utilized for training and preoperative planning purposes. As such, they must meet stringent requirements, with dimensional accuracy being of utmost importance. This study aimed to evaluate the precision and accuracy of anatomical bone models manufactured using three different AM technologies: digital light processing (DLP), fused deposition modeling (FDM), and PolyJetting (PJ), built in three different part orientations. Additionally, the study sought to assess surgeons' perceptions of how well these models mimic real bones in simulated osteosynthesis. METHODS: Computer-aided design (CAD) models of six human radii were generated from computed tomography (CT) imaging data. Anatomical models were then manufactured using the three aforementioned technologies and in three different part orientations. The surfaces of all models were 3D-scanned and compared with the original CAD models. Furthermore, an anatomical model of a proximal femur including a metastatic lesion was manufactured using the three technologies, followed by (mock) osteosynthesis performed by six surgeons on each type of model. The surgeons' perceptions of the quality and haptic properties of each model were assessed using a questionnaire. RESULTS: The mean dimensional deviations from the original CAD model ranged between 0.00 and 0.13 mm with maximal inaccuracies < 1 mm for all models. In surgical simulation, PJ models achieved the highest total score on a 5-point Likert scale ranging from 1 to 5 (with 1 and 5 representing the lowest and highest level of agreement, respectively), (3.74 ± 0.99) in the surgeons' perception assessment, followed by DLP (3.41 ± 0.99) and FDM (2.43 ± 1.02). Notably, FDM was perceived as unsuitable for surgical simulation, as the material melted during drilling and sawing. CONCLUSIONS: In conclusion, the choice of technology and part orientation significantly influenced the accuracy and precision of additively manufactured bone models. However, all anatomical models showed satisfying accuracies and precisions, independent of the AM technology or part orientation. The anatomical and functional performance of FDM models was rated by surgeons as poor.

Surgical Force: Initial Study and Clinical Implications in the Assessment of Ureteral Access Sheath Induced Injury.

Purpose: Ureteral access sheaths (UAS) pose the risk of severe ureteral injury. Our prior studies revealed forces ≤6 Newtons (N) prevent ureteral injury. Accordingly, we sought to define the force urologists and residents in training typically use when placing a UAS. Materials and Methods: Among urologists and urology residents attending two annual urological conferences in 2022, 121 individuals were recruited for the study. Participants inserted 12F, 14F, and 16F UAS into a male genitourinary model containing a concealed force sensor; they also provided demographic information. Analysis was completed using t-tests and Chi-square tests to identify group differences when passing a 16F sheath UAS. Participant traits associated with surpassing or remaining below a minimal force threshold were also explored through polychotomous logistic regression. Results: Participant force distributions were as follows: ≤4N (29%), >6N (45%), and >8N (32%). More years of practice were significantly associated with exerting >6N relative to forces between 4N and 6N; results for >8N relative to 4N and 8N were similar. Compared to high-volume ureteroscopists (those performing >20 ureteroscopies/month), physicians performing ≤20 ureteroscopies/month were significantly less likely to exert forces ≤4N (p = 0.017 and p = 0.041). Of those surpassing 6N and 8N, 15% and 18%, respectively, were high-volume ureteroscopists. Conclusions: Despite years of practice or volume of monthly ureteroscopic cases performed, most urologists failed to pass 16F access sheaths within the ideal range of 4N to 6N (74% of participants) or within a predefined safe range of 4N to 8N (61% of participants).

Finite element analysis of a customized implant in PMMA coupled with the cranial bone.

This computational study investigates the effect of the Von Misses stresses and deformations distribution generated by coupling a customized cranial implant with its fixation system for anchoring in the cranial bone of a specific patient. Three simulations were carried out under static loads, in different areas of the implant and during the rest-activity; and another three simulations were considered preset maximum intracranial pressures. Anatomical models were obtained by computed tomography. The design of the device to be implanted was carried out by applying reverse engineering processes, from the corresponding computer-aided design (CAD) model of the bone structure of interest. Likewise, the anchoring system was modeled in detail. Loads were applied at three points on the custom implant. The stress distribution on the artificial plate and the implant-natural bone interface was analyzed. The distribution of the stresses caused by the internal load states on the plate and the anchoring system was also studied. The neurocranial reconstruction with the customized polymethylmethacrylate (PMMA)-based implant and the finite element analysis demonstrated that the fixation and coupling system of the bone-implant interface guarantees adequate protection for the internal structures of the restored area. In addition, the custom-designed and placed implant will not cause non-physiological harm to the patient. Nor will failures occur in the anchoring system.

Dissection in biology education compared to alternative methods in terms of their influence on students' emotional experience.

Introduction: Dissecting animal organs is a method of biology teaching that offers a direct and authentic view into morphological structures and enables hands-on activity and multisensory experiences. However, the dissection process is often associated with certain (negative) emotions that might hinder successful learning. One such emotion that is particularly common during dissection is disgust. Experiencing disgust can negatively affect emotional experiences. Consequently, alternatives for dissection in biology lessons are being sought. Methods: In this study, the method of dissection is compared with two common methods of teaching the anatomy of the mammalian eye: watching a video and working with an anatomical model. The focus of the comparison is on the influence on the following emotional qualities of experience: perceived disgust, perceived interest, well-being and boredom. Two hundred and eighteen students (Mage = 14.19, SDage = 1.02 years, 52% female) from secondary schools in Germany participated in a two-hour lesson on the anatomy of the mammalian eye using one of the three aforementioned teaching methods. Findings: Our results show that perceived disgust was higher for the dissection group than in the ones that worked with a video or a model. We found that dissecting and watching a video led to a similar level of interest, well-being, and boredom. The anatomical model was perceived as less disgusting but more boring than the dissection. The detailed videos of a dissection seem to offer similar positive emotional experiences when compared to dissecting in class and may be an alternative approach when teachers have concerns about performing a real dissection.

Anatomically Integrated In-Place Visualization of Patient Data for Cooperative Tasks with a Case Study on a Neurosurgical Ward.

The workflow in modern hospitals entails that the medical treatment of a patient is distributed between several physicians and nurses. This leads to intensive cooperation, which takes place under particular time pressure and requires efficient conveyance of relevant patient-related medical data to colleagues. This requirement is difficult to achieve with traditional data representation approaches. In this paper, we introduce a novel concept of anatomically integrated in-place visualization designed to engage with cooperative tasks on a neurosurgical ward by using a virtual patient's body as spatial representation of visually encoded abstract medical data. Based on the findings of our field studies, we provide a set of formal requirements and procedures for this kind of visual encoding. Moreover, we implemented a prototype on a mobile device that supports the diagnosis of spinal disc herniation and has been evaluated by 10 neurosurgeons. The physicians have assessed the proposed concept as beneficial, especially emphasizing the advantages of the anatomical integration such as intuitiveness and a better data availability due to providing all information at a glance. Particularly, four of nine respondents have stressed solely benefits of the concept, other four have mentioned benefits with some limitations and only one person has seen no benefits.

Exoscope and operative microscope for training in microneurosurgery: A laboratory investigation on a model of cranial approach.

Objective: To evaluate the viability of exoscopes in the context of neurosurgical education and compare the use of a 4k3D exoscope to a traditional operative microscope in the execution of a task of anatomic structure identification on a model of cranial approach. Material and methods: A cohort of volunteer residents performed a task of anatomical structure identification with both devices three times across an experimental period of 2 months. We timed the residents' performances, and the times achieved were analyzed. The volunteers answered two questionnaires concerning their opinions of the two devices. Results: Across tries, execution speed improved for the whole cohort. When using the exoscopes, residents were quicker to identify a single anatomical structure starting from outside the surgical field when deep structures were included in the pool. In all other settings, the two devices did not differ in a statistically significant manner. The volunteers described the exoscope as superior to the microscope in all the aspects the questionnaires inquired about, besides the depth of field perception, which was felt to be better with the microscope. Volunteers furthermore showed overwhelming support for training on different devices and with models of surgical approaches. Conclusion: The exoscope appeared to be non-inferior to the microscope in the execution of a task of timed identification of anatomical structures on a model of cranial approach carried out by our cohort of residents. In the questionnaires, the residents reported the exoscope to be superior to the microscope in eight of nine investigated domains. Further studies are needed to investigate the use of the exoscope in learning of microsurgical skills.

Evaluation of Chinese populational exposure to environmental electromagnetic field based on stochastic dosimetry and parametric human modelling.

This study aimed to estimate the distribution of the whole-body averaged specific absorption rate (WBSAR) using several measurable physique parameters for Chinese adult population exposed to environmental electromagnetic fields (EMFs) of current wireless communication frequencies, and to discuss the effects of these physique parameters in the frequency-dependent dosimetric results. The physique distribution of Chinese adults was obtained from the National Physical Fitness and Health Database comprising 81,490 adult samples. The number of physique parameters used to construct the surrogate model was reduced to three via mutual information analysis. A stochastic method with 40 deterministic simulations was used to generate frequency-dependent and gender-specific surrogate models for WBSAR via polynomial chaos expansion. In the simulations, we constructed anatomically correct models conforming to the targeted physique parameters via deformable human modelling technique, which was based on deep learning from the image database including 767 Chinese adults. Thereafter, we analysed the sensitivity of the physique parameters to WBSAR by covariance-based Sobol decomposition. The results indicated that the generated models were consistent with the targeted physique parameters. The estimated dosimetric results were validated using finite-difference time-domain simulations (the error was < 6% across all the investigated frequencies for WBSAR). The novelty of the study included that it demonstrated the feasibility of estimating the individual WBSAR using a limited number of physique parameters with the aid of surrogate modelling. In addition, the population-based distribution of the WBSAR in Chinese adults was firstly presented in the manuscript. The results also indicated that the different combinations of physique parameter, dependent on genders and frequencies, significantly influenced the WBSAR, although the general conservativeness of the guidelines of the International Commission on Non-Ionizing Radiation and Protection can be confirmed in the surveyed population.

A Novel Ureteroscopy Training Platform That Utilizes CT Urograms to Replicate Complex Renal Collecting System Anatomies.

Introduction: Flexible ureteroscopy (fURS) is a one-person surgical technique, limiting trainees' ability to practice intraoperatively. Although well suited for simulation training, few existing fURS simulators can accurately reproduce complex renal collecting system anatomies. We developed an anatomically accurate fURS simulator using three-dimensional (3D) reconstruction of CT urograms and 3D printing technology to address this need. Materials and Methods: Patient-specific CT urograms were used to create 3D reconstruction of the renal collecting system using Slicer™. 3D models were modified using Blender™. Hollow, elastomer kidney models were created using an Objet 3D™ printer. To test and evaluate the new fURS simulator, 25 volunteers were recruited (5 novices, 13 residents, and 7 urologists). Participants were asked to explore the model with fURS and were evaluated on their ability to deduce its 3D anatomy, their ability to navigate to prespecified calices, and their time to task completion. Furthermore, participants were asked to compare the anatomical model with existing fURS benchtop models (Cook Medical™ and Limbs & Things™) on several criteria, including internal visualization, tactile feedback, and overall functional and teaching fidelity, in a survey. Results: We were able to create a fURS simulator that accurately replicates anatomically complex renal collecting systems. In exploring the model, we noted that unlike staff urologists, novices and residents often completely missed lower pole calices. A survey comparison between our simulator and comparable benchtop simulators revealed consistently better ratings of our simulator on all criteria (p < 0.05). Conclusions: We were able to create an anatomically accurate fURS simulator that provides a more realistic scoping experience. Preliminary testing revealed that trainees will benefit from this simulator, particularly with respect to learning how to navigate challenging collecting systems.

A probability model for anatomical robust optimisation in head and neck cancer proton therapy.

Objective.Develop an anatomical model based on the statistics of the population data and evaluate the model for anatomical robust optimisation in head and neck cancer proton therapy.Approach.Deformable image registration was used to build the probability model (PM) that captured the major deformation from patient population data and quantified the probability of each deformation. A cohort of 20 nasopharynx patients was included in this retrospective study. Each patient had a planning CT and 6 weekly CTs during radiotherapy. We applied the model to 5 test patients. Each test patient used the remaining 19 training patients to build the PM and estimate the likelihood of a certain anatomical deformation to happen. For each test patient, a spot scanning proton plan was created. The PM was evaluated using proton spot location deviation and dose distribution.Main results. Using the proton spot range, the PM can simulate small non-rigid variations in the first treatment week within 0.21 ± 0.13 mm. For overall anatomical uncertainty prediction, the PM can reduce anatomical uncertainty from 4.47 ± 1.23 mm (no model) to 1.49 ± 1.08 mm at week 6. The 95% confidence interval (CI) of dose metric variations caused by actual anatomical deformations in the first week is -0.59% ∼ -0.31% for low-risk CTD95, and 0.84-3.04 Gy for parotidDmean. On the other hand, the 95% CI of dose metric variations simulated by the PM at the first week is -0.52 ∼ -0.34% for low-risk CTVD95, and 0.58 ∼ 2.22 Gy for parotidDmean.Significance.The PM improves the estimation accuracy of anatomical uncertainty compared to the previous models and does not depend on the acquisition of the weekly CTs during the treatment. We also provided a solution to quantify the probability of an anatomical deformation. The potential of the model for anatomical robust optimisation is discussed.

Additive Manufacturing of Anatomical Poly(d,l-lactide) Scaffolds.

Poly(lactide) (PLA) is one of the most investigated semicrystalline polymers for material extrusion (MEX) additive manufacturing (AM) techniques based on polymer melt processing. Research on its application for the development of customized devices tailored to specific anatomical parts of the human body can provide new personalized medicine strategies. This research activity was aimed at testing a new multifunctional AM system for the design and fabrication by MEX of anatomical and dog-bone-shaped PLA samples with different infill densities and deposition angles. In particular, a commercial PLA filament was employed to validate the computer-aided design (CAD) and manufacturing (CAM) process for the development of scaffold prototypes modeled on a human bone defect. Physical-chemical characterization of the obtained samples by 1H-NMR spectroscopy, size exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) demonstrated a small reduction of polymer molecular weight (~5%) due to thermal processing, as well as that the commercial polymer employed was a semicrystalline poly(d,l-lactide). Mechanical characterization highlighted the possibility of tuning elastic modulus and strength, as well as the elongation at break up to a 60% value by varying infill parameters.

In Vitro Anatomical Models for Nasal Drug Delivery.

Nasal drug delivery has been utilized for locally acting diseases for decades. The nose is also a portal to the systemic circulation and central nervous system (CNS). In the age of SARS-CoV2, the development of nasal sprays for vaccination and prophylaxis of respiratory diseases is increasing. As the number of nasal drug delivery applications continue to grow, the role of targeted regional deposition in the nose has become a factor is nasal drug development. In vitro tools such as nasal casts help facilitate formulation and product development. Nasal deposition has been shown to be linked to pharmacokinetic outcomes. Developing an understanding of the complex nasal anatomy and intersubject variability can lead to a better understanding of where the drug will deposit. Nasal casts, which are replicas of the human nasal cavity, have evolved from models made from cadavers to complex 3D printed replicas. They can be segmented into regions of interest for quantification of deposition and different techniques have been utilized to quantify deposition. Incorporating a nasal cast program into development can help differentiate formulations or physical forms such as nasal powder versus a liquid. Nasal casts can also help develop instructions for patient use to ensure deposition in the target deposition site. However, regardless of the technique used, this in vitro tool should be validated to ensure the results reflect the in vivo situation. In silico, CFD simulation or other new developments may in future, with suitable validation, present additional approaches to current modelling, although the complexity and wide degree of variability in nasal anatomy will remain a challenge. Nonetheless, nasal anatomical models will serve as effective tools for improving the understanding of nasal drug delivery.

Algorithms used in medical image segmentation for 3D printing and how to understand and quantify their performance.

BACKGROUND: 3D printing (3DP) has enabled medical professionals to create patient-specific medical devices to assist in surgical planning. Anatomical models can be generated from patient scans using a wide array of software, but there are limited studies on the geometric variance that is introduced during the digital conversion of images to models. The final accuracy of the 3D printed model is a function of manufacturing hardware quality control and the variability introduced during the multiple digital steps that convert patient scans to a printable format. This study provides a brief summary of common algorithms used for segmentation and refinement. Parameters for each that can introduce geometric variability are also identified. Several metrics for measuring variability between models and validating processes are explored and assessed. METHODS: Using a clinical maxillofacial CT scan of a patient with a tumor of the mandible, four segmentation and refinement workflows were processed using four software packages. Differences in segmentation were calculated using several techniques including volumetric, surface, linear, global, and local measurements. RESULTS: Visual inspection of print-ready models showed distinct differences in the thickness of the medial wall of the mandible adjacent to the tumor. Volumetric intersections and heatmaps provided useful local metrics of mismatch or variance between models made by different workflows. They also allowed calculations of aggregate percentage agreement and disagreement which provided a global benchmark metric. For the relevant regions of interest (ROIs), statistically significant differences were found in the volume and surface area comparisons for the final mandible and tumor models, as well as between measurements of the nerve central path. As with all clinical use cases, statistically significant results must be weighed against the clinical significance of any deviations found. CONCLUSIONS: Statistically significant geometric variations from differences in segmentation and refinement algorithms can be introduced into patient-specific models. No single metric was able to capture the true accuracy of the final models. However, a combination of global and local measurements provided an understanding of important geometric variations. The clinical implications of each geometric variation is different for each anatomical location and should be evaluated on a case-by-case basis by clinicians familiar with the process. Understanding the basic segmentation and refinement functions of software is essential for sites to create a baseline from which to evaluate their standard workflows, user training, and inter-user variability when using patient-specific models for clinical interventions or decisions.

DIR-based models to predict weekly anatomical changes in head and neck cancer proton therapy.

Objective. We proposed two anatomical models for head and neck patients to predict anatomical changes during the course of radiotherapy.Approach. Deformable image registration was used to build two anatomical models: (1) the average model (AM) simulated systematic progressive changes across the patient cohort; (2) the refined individual model (RIM) used a patient's CT images acquired during treatment to update the prediction for each individual patient. Planning CTs and weekly CTs were used from 20 nasopharynx patients. This dataset included 15 training patients and 5 test patients. For each test patient, a spot scanning proton plan was created. Models were evaluated using CT number differences, contours, proton spot location deviations and dose distributions.Main results. If no model was used, the CT number difference between the planning CT and the repeat CT at week 6 of treatment was on average 128.9 Hounsfield Units (HU) over the test population. This can be reduced to 115.5 HU using the AM, and to 110.5 HU using the RIM3(RIM, updated at week (3). When the predicted contours from the models were used, the average mean surface distance of parotid glands can be reduced from 1.98 (no model) to 1.16 mm (AM) and 1.19 mm (RIM3) at week 6. Using the proton spot range, the average anatomical uncertainty over the test population reduced from 4.47 ± 1.23 (no model) to 2.41 ± 1.12 mm (AM), and 1.89 ± 0.96 mm (RIM3). Based on the gamma analysis, the average gamma index over the test patients was improved from 93.87 ± 2.48 % (no model) to 96.16 ± 1.84% (RIM3) at week 6.Significance. The AM and the RIM both demonstrated the ability to predict anatomical changes during the treatment. The RIM can gradually refine the prediction of anatomical changes based on the AM. The proton beam spots provided an accurate and effective way for uncertainty evaluation.

Effect of a three-dimensional (3D) printed kidney model on patient understanding of the percutaneous nephrolithotomy procedure: a preliminary study.

Three-dimensional (3D) printed anatomical models can provide cognitive anatomical information. We aimed to study the effect of a 3D printed kidney model on patient understanding of kidney anatomy and the percutaneous nephrolithotomy (PCNL) procedure as well as the overall patient satisfaction with the model. Seven patients who underwent PCNL were enrolled in the study. Personalized 3D printed kidney models were constructed based on the patients' computed tomography images. Patients completed two questionnaires regarding their understanding and satisfaction with the use of the 3D printed kidney model before and after using the model during informed consent. The mean age of the study population was 58.0 years. Comparison of patient understanding and satisfaction between the two questionnaires showed a general trend toward better understanding and improved satisfaction with use of 3D printed kidney models. Statistically significant results were seen for understanding of kidney anatomy, stone size, procedure, and satisfaction (p values 0.046, 0.025, 0.046, and 0.046, respectively). Five of the seven patients (71.4%) answered that the model was very useful. However, none of the patients answered that the cost was appropriate. In the current study, patients showed improved understanding of the kidney anatomy and the PCNL procedure and higher satisfaction with using the 3D printed kidney model during informed consent. With further studies using larger patient numbers and decreased production cost, using 3D printed kidney models has the potential to be a useful adjunct for patient understanding during PCNL.

An anatomical model for studying cerebellar tonsillar herniation related to raised intracranial pressure.

Brain herniation is one of the most feared complications of many neurological pathologies. However, current understanding of the mechanisms behind brain herniation syndromes is poor. By investigating the correlations between raised intracranial pressure (ICP) and herniation of the cerebellar tonsils, we hope to develop a model that can be used to study intracranial fluid dynamics and its effects on brain tissue. This will facilitate evaluation of patients with elevated ICP and development of novel treatments including surgical approaches for decompressing the posterior cranial fossa and upper cervical spine. A standard suboccipital surgical approach was used to expose the foramen magnum and observe movements of the cerebellar tonsils in fresh cadavers. A urinary Foley catheter balloon in the parietal extradural space was used to simulate a mass effect while ICP was monitored. The baseline anatomy differed widely among the cadaver specimens. However, and overall, we found that as ICP rises, the cerebellar tonsils descend through the foramen magnum at a rate of 0.3 mm per 1 mmHg increase in ICP. A mean descent of 6.2 mm was observed for a mean ICP increase of 17 mmHg. In this cadaveric study, we present a method and model for exploring brain herniation syndromes in the context of ICP changes. This could allow for further models to study the effects of other neuropathologies on the cerebellar tonsils, including posterior cranial fossa mass lesions and cerebellar hemorrhage.

Establishment and Application of dose evaluation model for typical mammal in dry region in China / 中华放射医学与防护杂志

Objective:To establish a simplified anatomical model with the selected rabbits widely distributed in China′s dry region as the reference species and compare the result of internal exposure dose coefficients based on the present mode and ERICA.Methods:A simplified anatomical model based on anatomy and geometry was established for rabbits. Combined with Monte Carlo program, the deposited energy of radionuclide particles in rabbit tissues/organs was obtained, and the internal and external exposure dose coefficient for rabbits was calculated following the empirical formula.Results:Simplified anatomy model-based dose coefficients were 129I 4.81 × 10 -6, 137Cs 4.34 × 10 -5, and 134Cs 3.81 × 10 -5(μGy·h -1)/(Bq·kg -1) for internal exposure and 129I 3.16 × 10 -7, 137Cs 2.39 × 10 -4 and 134Cs 6.22 × 10 -4(μGy·h -1)/(Bq· kg -1) for external exposure. respectively. ERICA-based dose coefficients were 129I 4.44 × 10 -5, 137Cs 1.94 × 10 -4 and 134Cs 2.34 × 10 -4(μGy·h -1)/(Bq·kg -1) for internal exposure and 129I 2.19 × 10 -6, 137Cs 2.52 × 10 -4 and 134Cs 6.95 × 10 -4(μGy·h -1)/(Bq·kg -1) for external exposure, respectively. Conclusions:The simplified anatomical model established is based on the measured data and focuses on the radiation doses to biological tissues/organs, and the calculated result based on the present model are closer to the actual situation, and can provide reference values for the reference biological evaluation of non-human species.

Independent Lung Ventilation-Experimental Studies on a 3D Printed Respiratory Tract Model.

Independent lung ventilation (ILV) is a life-saving procedure in unilateral pulmonary pathologies. ILV is underused in clinical practice, mostly due to the technically demanding placement of a double lumen endotracheal tube (ETT). Moreover, the determination of ventilation parameters for each lung in vivo is limited. In recent years, the development of 3D printing techniques enabled the production of highly accurate physical models of anatomical structures used for in vitro research, considering the high risk of in vivo studies. The purpose of this study was to assess the influence of double-lumen ETT on the gas transport and mixing in the anatomically accurate 3D-printed model of the bronchial tree, with lung lobes of different compliances, using various ventilation modes. The bronchial tree was obtained from Respiratory Drug Delivery (RDD Online, Richmond, VA, USA), processed and printed by a dual extruder FFF 3D printer. The test system was also composed of left side double-lumen endotracheal tube, Siemens Test Lung 190 and anesthetic breathing bag (as lobes). Pressure and flow measurements were taken at the outlets of the secondary bronchus. The measured resistance increased six times in the presence of double-lumen ETT. Differences between the flow distribution to the less and more compliant lobe were more significant for the airways with double-lumen ETT. The ability to predict the actual flow distribution in model airways is necessary to conduct effective ILV in clinical conditions.

Functional and Cosmetic Outcome after Reconstruction of Isolated, Unilateral Orbital Floor Fractures (Blow-Out Fractures) with and without the Support of 3D-Printed Orbital Anatomical Models.

The present study aimed to analyze if a preformed "hybrid" patient-specific orbital mesh provides a more accurate reconstruction of the orbital floor and a better functional outcome than a standardized, intraoperatively adapted titanium implant. Thirty patients who had undergone surgical reconstruction for isolated, unilateral orbital floor fractures between May 2016 and November 2018 were included in this study. Of these patients, 13 were treated conventionally by intraoperative adjustment of a standardized titanium mesh based on assessing the fracture's shape and extent. For the other 17 patients, an individual three-dimensional (3D) anatomical model of the orbit was fabricated with an in-house 3D-printer. This model was used as a template to create a so-called "hybrid" patient-specific titanium implant by preforming the titanium mesh before surgery. The functional and cosmetic outcome in terms of diplopia, enophthalmos, ocular motility, and sensory disturbance trended better when "hybrid" patient-specific titanium meshes were used but with statistically non-significant differences. The 3D-printed anatomical models mirroring the unaffected orbit did not delay the surgery's timepoint. Nonetheless, it significantly reduced the surgery duration compared to the traditional method (58.9 (SD: 20.1) min versus 94.8 (SD: 33.0) min, p-value = 0.003). This study shows that using 3D-printed anatomical models as a supporting tool allows precise and less time-consuming orbital reconstructions with clinical benefits.

Modified conventional gait model vs. Six degrees of freedom model: A comparison of lower limb kinematics and associated error.

BACKGROUND: The conventional gait model (CGM) is commonly utilised within clinical motion analysis but has a number of inherent limitations. To overcome some of these limitations modifications have been made to the CGM and six-degrees of freedom models (6DoF) have been developed. RESEARCH QUESTION: How comparable are lower limb kinematics calculated using modified CGM and 6DoF models and what is the error associated with the output of each model during walking? METHODS: Ten healthy males attended two gait analysis sessions, in which they walked at a self-selected pace, while a 10-camera motion capture system recorded lower limb kinematics. Hip, knee and ankle joint kinematics in all three anatomical planes were calculated using a modified CGM, with medial anatomical markers and a three-dimensional foot added, and 6DoF. Mean absolute differences were calculated on a point-by-point basis over the walking gait cycle and interpreted relative to a 5° threshold to explore the comparability of model outputs. The standard error of the measurement (SEM) was also calculated on a point-by-point basis over the walking gait cycle for each model. RESULTS: Mean absolute differences above 5° were reported between the two model outputs in 58-86% of the walking gait cycle at the knee in the frontal plane, and over the entire walking gait cycle at the hip and knee in the transverse plane. SEM was typically larger for the modified CGM compared to the 6DoF, with the highest SEM values reported at the knee in the frontal plane, and the hip and the knee in the transverse plane. SIGNIFICANCE: Caution should be taken when looking to compare findings between studies utilising modified CGM and 6DoF outside of the sagittal plane, especially at the hip and knee. The reduced SEM associated with the 6DoF suggests this modelling approach may be preferable.