Evaluation of monte carlo to support commissioning of the treatment planning system of new pencil beam scanning proton therapy facilities.

Objective. To demonstrate the potential of Monte Carlo (MC) to support the resource-intensive measurements that comprise the commissioning of the treatment planning system (TPS) of new proton therapy facilities.Approach. Beam models of a pencil beam scanning system (Varian ProBeam) were developed in GATE (v8.2), Eclipse proton convolution superposition algorithm (v16.1, Varian Medical Systems) and RayStation MC (v12.0.100.0, RaySearch Laboratories), using the beam commissioning data. All models were first benchmarked against the same commissioning data and validated on seven spread-out Bragg peak (SOBP) plans. Then, we explored the use of MC to optimise dose calculation parameters, fully understand the performance and limitations of TPS in homogeneous fields and support the development of patient-specific quality assurance (PSQA) processes. We compared the dose calculations of the TPSs against measurements (DDTPSvs.Meas.) or GATE (DDTPSvs.GATE) for an extensive set of plans of varying complexity. This included homogeneous plans with varying field-size, range, width, and range-shifters (RSs) (n= 46) and PSQA plans for different anatomical sites (n= 11).Main results. The three beam models showed good agreement against the commissioning data, and dose differences of 3.5% and 5% were found for SOBP plans without and with RSs, respectively. DDTPSvs.Meas.and DDTPSvs.GATEwere correlated in most scenarios. In homogeneous fields the Pearson's correlation coefficient was 0.92 and 0.68 for Eclipse and RayStation, respectively. The standard deviation of the differences between GATE and measurements (±0.5% for homogeneous and ±0.8% for PSQA plans) was applied as tolerance when comparing TPSs with GATE. 72% and 60% of the plans were within the GATE predicted dose difference for both TPSs, for homogeneous and PSQA cases, respectively.Significance. Developing and validating a MC beam model early on into the commissioning of new proton therapy facilities can support the validation of the TPS and facilitate comprehensive investigation of its capabilities and limitations.

It was the best of times, it was the worst of times: a tale of two cities-Beijing and Shanghai-why the divergent COVID-19 control outcomes?

Coronavirus disease 2019 (COVID-19) both creates and complicates public health challenges. Yet, the pandemic also provides a unique lens for dissecting complex issues in global health that could benefit society in the long run. In this article, we discuss the underlying reasons that can help explain the divergent COVID-19 control outcomes between Beijing and Shanghai-two advanced metropolises that are similar in their municipal capacity, administrative capability and pandemic strategy. We hope insights from this investigation contribute to the development of disease prevention systems, such as context-specific and data-driven public health strategies that could yield optimal pandemic control outcomes with minimal unintended consequences, both amid and beyond COVID-19.

How to avoid future "Covid-19 origins" questions?

Origins debates regarding Covid-19 are gaining momentum again. In light of the continued infections and deaths of Covid-19 seen in countries rich and poor, rather than focusing the approach with "whodunit", developing solutions that can help societies become better prepared for future pandemics might be a more meaningful way to move forward. In this paper, we propose a solution that could help society better predict and prevent future pandemics. A system could allow humans to anonymously report potential infectious disease outbreaks without fearing backlash or prejudice and could automatically surveil for potential disease transfers or virus leaks. The proposed autonomous and anonymous pandemic reporting and surveillance system has the potential to help health officials locate infectious disease outbreaks before they form into pandemics. And in turn, it better prevents future pandemics and avoids Covid-19 origins debates.

An study on the influence of collagen fiber directions in TAVs performance using FEM.

Transcatheter Aortic Valve Implantation (TAVI) or Replacement (TAVR) is a promising treatment for aortic valve stenosis, consisting of a procedure to replace a damaged native aortic valve by a bioprosthetic one. This replacement valve control the flow of blood using leaflets that are similar to the ones of a native aortic valve. Commonly manufactured using bovine or porcine pericardium, it is a tissue histologically composed of collagen fibers embedded into a nearly-isotropic matrix, where their distribution makes the pericardium behave as an anisotropic hyperelastic material. Because of such complicated behavior, bioprosthetic pericardium valves are, as expected, sensitive to the distribution and orientation of these fibers in such device. Therefore, the objective of this work is a thorough systematic study on the influence of these fibers' distribution. First, a Finite Element model of a bioprosthetic valve is generated; then, a material routine to accurately describe the behavior of pericardium is implemented in a commercial software package; in addition, a dedicated algorithm to specify the direction of fibers is developed. Finally, a systematic study on the influence that fiber orientations have on the overall behavior of the TAV is performed. As a result of this study, two extreme behaviors are highlighted depending on the preferential orientation of collagen fibers; namely, one with fibers in circumferential direction and the opposite with fibers in an axial orientation. Then, it is concluded that the behavior of fibers in circumferential direction is very sensitive to small variations of the orientation angle, whereas such orientation is not as determining when the aim is to achieve a behavior near to the one corresponding with axial orientation.

A multichannel feature-based approach for longitudinal lung CT registration in the presence of radiation induced lung damage.

Quantifying parenchymal tissue changes in the lungs is imperative in furthering the study of radiation induced lung damage (RILD). Registering lung images from different time-points is a key step of this process. Traditional intensity-based registration approaches fail this task due to the considerable anatomical changes that occur between timepoints. This work proposes a novel method to successfully register longitudinal pre- and post-radiotherapy (RT) lung computed tomography (CT) scans that exhibit large changes due to RILD, by extracting consistent anatomical features from CT (lung boundaries, main airways, vessels) and using these features to optimise the registrations. Pre-RT and 12 month post-RT CT pairs from fifteen lung cancer patients were used for this study, all with varying degrees of RILD, ranging from mild parenchymal change to extensive consolidation and collapse. For each CT, signed distance transforms from segmentations of the lungs and main airways were generated, and the Frangi vesselness map was calculated. These were concatenated into multi-channel images and diffeomorphic multichannel registration was performed for each image pair using NiftyReg. Traditional intensity-based registrations were also performed for comparison purposes. For the evaluation, the pre- and post-registration landmark distance was calculated for all patients, using an average of 44 manually identified landmark pairs per patient. The mean (standard deviation) distance for all datasets decreased from 15.95 (8.09) mm pre-registration to 4.56 (5.70) mm post-registration, compared to 7.90 (8.97) mm for the intensity-based registrations. Qualitative improvements in image alignment were observed for all patient datasets. For four representative subjects, registrations were performed for three additional follow-up timepoints up to 48 months post-RT and similar accuracy was achieved. We have demonstrated that our novel multichannel registration method can successfully align longitudinal scans from RILD patients in the presence of large anatomical changes such as consolidation and atelectasis, outperforming the traditional registration approach both quantitatively and through thorough visual inspection.

In Silico Ventilation Within the Dose-Volume is Predictive of Lung Function Post-radiation Therapy in Patients with Lung Cancer.

Lung cancer is a leading cause of death worldwide. Radiation therapy (RT) is one method to treat this disease. A common side effect of RT for lung cancer is radiation-induced lung damage (RILD) which leads to loss of lung function. RILD often compounds pre-existing smoking-related regional lung function impairment. It is difficult to predict patient outcomes due to large variability in individual response to RT. In this study, the capability of image-based modelling of regional ventilation in lung cancer patients to predict lung function post-RT was investigated. Twenty-five patient-based models were created using CT images to define the airway geometry, size and location of tumour, and distribution of emphysema. Simulated ventilation within the 20 Gy isodose volume showed a statistically significant negative correlation with the change in forced expiratory volume in 1 s 12-months post-RT (p = 0.001, R = - 0.61). Patients with higher simulated ventilation within the 20 Gy isodose volume had a greater loss in lung function post-RT and vice versa. This relationship was only evident with the combined impact of tumour and emphysema, with the location of the emphysema relative to the dose-volume being important. Our results suggest that model-based ventilation measures can be used in the prediction of patient lung function post-RT.

Which One Is the Best for Living Donation: A Multiple-Artery Left Kidney Nephrectomy or a Right Kidney Nephrectomy?

INTRODUCTION: The current approach in living-donor kidney transplant is to preserve the best kidney for the donor and harvest the contralateral one. Due to a shorter renal vein and a greater incidence of venous thrombosis, left kidneys are more frequently elected. Notwithstanding, arterial anatomy may be complex and thus render the transplantation procedure more difficult and prone to complications. OBJECTIVES: To analyze the outcomes after multiple-artery left kidney nephrectomy (MALKN) and right kidney nephrectomy (RKN). RESULTS: Seventy-three cases were performed from 1999 to 2017 in our institution: 34 MALKN and 39 RKN. The mean operative time was significantly longer in MALKN. Warm ischemia time, donor and receptor hospital stay, and postoperative complications did not differ between groups. There was a positive correlation between renal arteries' ostia distance in MALKN and the duration of warm ischemia period. There was no significant difference in the incidence of acute tubular necrosis, first-year variations in serum creatinine, and glomerular filtration rate between groups. Long-term graft survival did not significantly differ between groups. Three cases of vein thrombosis after RKN were reported with graft loss. CONCLUSION: The safety and efficacy of MALKN does not differ from RKN, although there appears to be a higher incidence of vein thrombosis after right kidney transplantation. Despite being technically more demanding, particularly in cases with distant artery ostia, MALKN could be a better option than RKN for living donation, expanding the available donor pool, although more studies are needed to affirm this conclusion.

Toward adaptive radiotherapy for lung patients: feasibility study on deforming planning CT to CBCT to assess the impact of anatomical changes on dosimetry.

Changes in lung architecture during a course of radiotherapy can alter the planned dose distribution to the extent that it becomes clinically unacceptable. This study aims to validate a quantitative method of determining whether a replan is required during the course of conformal radiotherapy. The proposed method uses deformable image registration (DIR) to flexibly map planning CT (pCT) data to the anatomy of online CBCT images. The resulting deformed CT (dCT) images are used as a basis for assessing the effect of anatomical change on dose distributions. The study used retrospective data from a sample of seven replanned lung patients. The settings of an in-house, open-source DIR algorithm were first optimised for CT-to-CBCT registrations of the anatomy of the thorax. Using these optimised parameters, each patient's pCT was deformed to the CBCT acquired immediately before the replan. Registration accuracy was rigorously validated both geometrically and dosimetrically to confirm that the dCTs could reliably be used to inform replan decisions. A retrospective evaluation of the changes in dose delivered over time was then carried out for a single patient to demonstrate the clinical application of the proposed method. The geometric analysis showed good agreement between deformed structures and those same structures manually outlined on the CBCT images. Results were consistently better than those achieved with rigid-only registration. In the dosimetric analysis, dose distributions derived from the dCTs were found to match closely to the 'gold standard' replan CT (rCT) distributions across dose volume histogram and absolute dose difference measures. The retrospective analysis of serial CBCTs of a single patient produced reliable quantitative assessment of the dose delivery. Had the proposed method been available at the time of treatment, it would have enabled a more objective replan decision. DIR is a valuable clinical tool for dose recalculation in adaptive radiotherapy protocols for lung cancer patients.

Splenic torsion, a challenging diagnosis: Case report and review of literature.

INTRODUCTION: Wandering spleen is an unusual condition characterized by hypermobility of the spleen. This is a rare clinical entity and it's more common in childhood under 1 year of age and in third decade of life. In this second peak, it's more frequent in females. Clinical manifestations can vary from asymptomatic to abdominal emergency. Treatment is often surgical. PRESENTATION OF CASE: We presented a case report of splenic torsion from our hospital and a review of cases described in literature. This is a 40 year-old woman with complaints of upper abdominal pain associated with nausea and vomiting. A marked tenderness and a palpable abdominal mass on left hypochondrium were found as well as a slight increase in inflammatory parameters. A CT was performed and demonstrated findings compatible with splenic torsion. Surgery was performed doing laparoscopic splenectomy; Review of literature was made using the keyword combination: "wandering spleen". The research resulted in 451 articles. DISCUSSION: The physical examination and CT are fundamental for diagnosis. Surgery was performed and laparoscopic splenectomy was made because infarcted spleen; about the review of literature, the majority of patients were female and the average age at the time of diagnosis was 25.2 years. 69.5% needed splenectomy and 78.6% of surgeries were laparotomic. CONCLUSION: Splenic torsion is a rare but important differential diagnosis in patients presenting with acute abdomen. Diagnosis should be made promptly before development of life-threatening complications. Surgery is often necessary and splenopexy or splenectomy can be done.

Dicephalic Parapagus Conjoined Twins in a Large Fruit-eating Bat, Genus Artibeus (Chiroptera, Phyllostomidae).

Conjoined twinning is an embryological anomaly rarely reported in wild mammals and with only two previous records in Chiroptera. Here, we report a case of dicephalic parapagus conjoined twins in the Neotropical phyllostomid genus Artibeus. These twins are males and present separated heads and necks, but a conjoined trunk with an expanded upper thoracic region. They developed two complete forelimbs and two complete hindlimbs, all laterally to the trunk. There is a volume in the upper midback and between the heads that resembles a third rudimentary medial forelimb, but X-ray images only suggest the presence of medial skeletal elements of the pectoral girdle (clavicle and scapulae) in this region. The X-ray images also show that vertebral columns run separated from head until the base of lumbar region, where they form a single structure. Using ultrasound images, we detected the presence of two similarly sized and apparently separated hearts. The accumulation of study cases like this will help in the understanding of patterns and process behind this phenomena, and collection material plays a key role in this context.

Subclinical pulmonary abnormalities in childhood-onset systemic lupus erythematosus patients.

OBJECTIVE: The aims of this study were to analyze the pulmonary function of childhood-onset systemic lupus erythematosus (cSLE) patients and to identify possible correlations between the high-resolution computed chest tomography (HRCT) score, disease activity, disease cumulative damage, and the participants' quality of life. METHODS: Forty cSLE patients, median age: 14.1 years (range: 7.4-17.9), underwent spirometry and plethysmography. Carbon monoxide diffusing capacity (DLCO), HRCT, disease activity, disease cumulative damage, and quality of life were assessed. RESULTS: Pulmonary abnormalities were evident in 19/40 (47.5%) cSLE patients according to spirometry/DLCO. Forced expired volume in one second (FEV1%) was the parameter most affected (30%). The HRCT showed some abnormality in 22/30 patients (73%), which were minimal in 43%. Signs of airway affects were found in 50%. Twelve patients were hospitalized due to cSLE-related pulmonary complications before the study began (median discharge: 2.1 years earlier). Total lung capacity (TLC%), vital capacity (VC%), forced vital capacity (FVC%), and FEV1% were significantly lower in the group with hospitalization compared to the group without hospitalization (p = 0.0025, p = 0.0022, p = 0.0032, and p = 0.0004, respectively). Of note, DLCO was positively correlated with disease duration (r = +0.4; p = 0.01). The HRCT-score was negatively correlated with FEV1/VC (r = -0.63; p = 0.0002), FEV1 (r = -0.54; p = 0.018), FEF25%-75% (r = -0.67; p < 0.0001), and HRCT-score was positively correlated with resistance (r = +0.49; p = 0.0056). CONCLUSIONS: Almost half of patients with cSLE had subclinical pulmonary abnormalities, especially airway abnormalities. The cSLE-related pulmonary complications seem to determine long-term functional damage.

Transanal total mesorectal excision: a pure NOTES approach for selected patients.

BACKGROUND: The concept of natural orifice transluminal endoscopic surgery (NOTES) has stimulated the development of various "incisionless" procedures. One of the most popular is the transanal approach for rectal lesions. The aims of this study were to report how we standardized NOTES technique for transanal mesorectal excision without abdominal assistance, discuss the difficulties and surgical outcomes of this technique and report its feasibility in a small group of selected patients. METHODS: Three consecutive female patients underwent transanal NOTES rectal resection without transabdominal laparoscopic assistance for rectal lesions. Functional results were assessed with the Fecal Incontinence Quality of Life scale and the Wexner score. RESULTS: The technical steps are described in details and complemented with a video. All procedures were completed without transabdominal laparoscopic help. The mesorectal plane was entirely dissected without any disruption, and distal and circumferential margins were tumor-free. No major complications were observed. Functional results show a significant impairment after surgery with improvement at 6 months to levels near those of the preoperative period. CONCLUSIONS: The performance and publication of NOTES procedures are subject to much discussion. Despite the small number of patients, this procedure appears feasible and can be accomplished maintaining fecal continence and respecting oncologic principles.

Aneurisma cerebral roto por Candida parapsilosis tras endocarditis sobre válvula protésica / Ruptured cerebral aneurysm after a Candida parapsilosis prosthetic valve endocarditis

No disponible

Development and simultaneous application of multiple care protocols in critical care: a multicenter feasibility study.

OBJECTIVE: To test the feasibility of and interactions among three software-driven critical care protocols. DESIGN: Prospective cohort study. SETTING: Intensive care units in six European and American university hospitals. PATIENTS: 174 cardiac surgery and 41 septic patients. INTERVENTIONS: Application of software-driven protocols for cardiovascular management, sedation, and weaning during the first 7 days of intensive care. MEASUREMENTS AND RESULTS: All protocols were used simultaneously in 85% of the cardiac surgery and 44% of the septic patients, and any one of the protocols was used for 73 and 44% of study duration, respectively. Protocol use was discontinued in 12% of patients by the treating clinician and in 6% for technical/administrative reasons. The number of protocol steps per unit of time was similar in the two diagnostic groups (n.s. for all protocols). Initial hemodynamic stability (a protocol target) was achieved in 26+/-18 min (mean+/-SD) in cardiac surgery and in 24+/-18 min in septic patients. Sedation targets were reached in 2.4+/-0.2h in cardiac surgery and in 3.6 +/-0.2h in septic patients. Weaning protocol was started in 164 (94%; 154 extubated) cardiac surgery and in 25 (60%; 9 extubated) septic patients. The median (interquartile range) time from starting weaning to extubation (a protocol target) was 89 min (range 44-154 min) for the cardiac surgery patients and 96 min (range 56-205 min) for the septic patients. CONCLUSIONS: Multiple software-driven treatment protocols can be simultaneously applied with high acceptance and rapid achievement of primary treatment goals. Time to reach these primary goals may provide a performance indicator.

European biliary atresia registries: summary of a symposium.

Biliary atresia (BA) is a rare but potentially devastating disease. The European Biliary Atresia Registry (EBAR) was set up to improve data collection and to develop a pan-national and interdisciplinary strategy to improve clinical outcomes. From 2001 to 2005, 100 centers from 22 countries registered with EBAR via its website (www.biliary-atresia.com). In June 2006, the first meeting was held to evaluate results and launch further initiatives. During a 5-year period, 60 centers from 19 European countries and Israel sent completed registration forms for a total of 514 BA patients. Assuming the estimated incidence of BA in Europe is 1:18,000 live births, 35% of the expected 1488 patients from all EBAR participating countries were captured, suggesting that reporting arrangements need improvement. At the meeting, the cumulative evaluation of 928 BA patients including patients from other registries with variable follow-up revealed an overall survival of 78% (range from 41% to 92%), of whom 342 patients (37%) have had liver transplants. Survival with native liver ranged from 14% to 75%. There was a marked variance in reported management and outcome by country (e.g., referral patterns, timing of surgery, centralization of surgery). In conclusion, EBAR represents the first attempt at an overall evaluation of the outcome of BA from a pan-European perspective. The natural history and outcome of biliary atresia is of considerable relevance to a European population. It is essential that there is further support for a pan-European registry with coordination of clinical standards, further participation of parent support groups, and implementation of online data entry and multidisciplinary clinical and basic research projects.

Massive exophthalmos after traumatic carotid-cavernous fistula embolization.

An 18-year-old man without previous clinical problems developed a left traumatic carotid-cavernous fistula after a traffic accident. An endovascular embolization with coils was performed without success. The drainage was derived to the superior ophthalmic vein solely and clinical worsening occurred. Left eye proptosis, chemosis and intraocular pressure increased. Complete ophthalmoplegia developed and visual acuity decreased due to a central retinal vein obstruction. After a second embolization attempt the fistula was closed successfully but proptosis, chemosis and intraocular pressure remained uncontrolled despite medical treatment. Therefore an orbital decompression surgery was performed. Ophthalmoplegia, proptosis and chemosis improved and intraocular pressure was controlled. Although retinal hemorrhages persist, no neovascularization has developed. Central retinal vein occlusion in young patients seems to have a different etiology than in the elderly. In young patients, local factors are more frequently identified than systemic vascular diseases. Early detection of central retinal vein obstruction may prevent deterioration of visual acuity.