Leveraging Technology for Vestibular Assessment and Rehabilitation in the Operational Environment: A Scoping Review.

INTRODUCTION: The vestibular system, essential for gaze and postural stability, can be damaged by threats on the battlefield. Technology can aid in vestibular assessment and rehabilitation; however, not all devices are conducive to the delivery of healthcare in an austere setting. This scoping review aimed to examine the literature for technologies that can be utilized for vestibular assessment and rehabilitation in operational environments. MATERIALS AND METHODS: A comprehensive search of PubMed was performed. Articles were included if they related to central or peripheral vestibular disorders, addressed assessment or rehabilitation, leveraged technology, and were written in English. Articles were excluded if they discussed health conditions other than vestibular disorders, focused on devices or techniques not conducive to the operational environment, or were written in a language other than English. RESULTS: Our search strategy yielded 32 articles: 8 articles met our inclusion and exclusion criteria whereas the other 24 articles were rejected. DISCUSSION: There is untapped potential for leveraging technology for vestibular assessment and rehabilitation in the operational environment. Few studies were found in the peer-reviewed literature that described the application of technology to improve the identification of central and/or peripheral vestibular system impairments; triage of acutely injured patients; diagnosis; delivery and monitoring of rehabilitation; and determination of readiness for return to duty. CONCLUSIONS: This scoping review highlighted technology for vestibular assessment and rehabilitation feasible for use in an austere setting. Such technology may be leveraged for prevention; monitoring exposure to mechanisms of injury; vestibular-ocular motor evaluation; assessment, treatment, and monitoring of rehabilitation progress; and return-to-duty determination after vestibular injury. FUTURE DIRECTIONS: The future of vestibular assessment and rehabilitation may be shaped by austere manufacturing and 3D printing; artificial intelligence; drug delivery in combination with vestibular implantation; organ-on-chip and organoids; cell and gene therapy; and bioprinting.

Alcohol Use in Liver Transplant Recipients With Alcohol-related Liver Disease: A Comparative Assessment of Relapse Prediction Models.

BACKGROUND: The selection of liver transplant (LT) candidates with alcohol-related liver disease (ALD) is influenced by the risk of alcohol relapse (AR), yet the ability to predict AR is limited. We evaluate psychosocial factors associated with post-LT AR and compare the performance of high-risk alcoholism risk (HRAR), sustained alcohol use post-LT (SALT), and the Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT) scores in predicting relapse. METHODS: A retrospective analysis of ALD patients undergoing LT from 2015 to 2021 at a single US transplant center was performed. Risk factors associated with post-LT AR were evaluated and test characteristics of 3 prediction models were compared. RESULTS: Of 219 ALD LT recipients, 23 (11%) had AR during a median study follow-up of 37.5 mo. On multivariate analysis, comorbid psychiatric illness (odds ratio 5.22) and continued alcohol use after advice from a health care provider (odds ratio 3.8) were found to be significantly associated with post-LT AR. On sensitivity analysis, SIPAT of 30 was optimal on discriminating between ALD LT recipients with and without post-LT AR. SIPAT outperformed both the HRAR and SALT scores (c-statistic 0.67 versus 0.59 and 0.62, respectively) in identifying post-LT AR. However, all scores had poor positive predictive value (<25%). CONCLUSIONS: AR after LT is associated with comorbid psychiatric illness and lack of heeding health care provider advice to abstain from alcohol. Although SIPAT outperformed the HRAR and SALT scores in predicting AR, all are poor predictors. The current tools to predict post-LT AR should not be used to exclude LT candidacy.

Impact of the new kidney allocation system A2/A2B → B policy on access to transplantation among minority candidates.

Blood group B candidates, many of whom represent ethnic minorities, have historically had diminished access to deceased donor kidney transplantation (DDKT). The new national kidney allocation system (KAS) preferentially allocates blood group A2/A2B deceased donor kidneys to B recipients to address this ethnic and blood group disparity. No study has yet examined the impact of KAS on A2 incompatible (A2i) DDKT for blood group B recipients overall or among minorities. A case-control study of adult blood group B DDKT recipients from 2013 to 2017 was performed, as reported to the Scientific Registry of Transplant Recipients. Cases were defined as recipients of A2/A2B kidneys, whereas controls were all remaining recipients of non-A2/A2B kidneys. A2i DDKT trends were compared from the pre-KAS (1/1/2013-12/3/2014) to the post-KAS period (12/4/2014-2/28/2017) using multivariable logistic regression. Post-KAS, there was a 4.9-fold increase in the likelihood of A2i DDKT, compared to the pre-KAS period (odds ratio [OR] 4.92, 95% confidence interval [CI] 3.67-6.60). However, compared to whites, there was no difference in the likelihood of A2i DDKT among minorities post-KAS. Although KAS resulted in increasing A2/A2B→B DDKT, the likelihood of A2i DDKT among minorities, relative to whites, was not improved. Further discussion regarding A2/A2B→B policy revisions aiming to improve DDKT access for minorities is warranted.

Monte Carlo modeling of a Novalis Tx Varian 6 MV with HD-120 multileaf collimator.

A Monte Carlo model of the Novalis Tx linear accelerator equipped with high-definition multileaf collimator (HD-120 HD-MLC) was commissioned using ionization chamber measurements in water. All measurements in water were performed using a liquid filled ionization chamber. Film measurements were made using EDR2 film in solid water. Open rectangular fields defined by the jaws or the HD-MLC were used for comparison against measurements. Furthermore, inter- and intraleaf leakage calculated by the Monte Carlo model was compared against film measurements. The statistical uncertainty of the Monte Carlo calculations was less than 1% for all simulations. Results for all regular field sizes show an excellent agreement with commissioning data (percent depth-dose curves and profiles), well within 1% of difference in the relative dose and 1 mm distance to agreement. The computed leakage through HD-MLCs shows good agreement with film measurements. The Monte Carlo model developed in this study accurately represents the new Novalis Tx Varian linac with HD-MLC and can be used for reliable patient dose calculations.

Effects of rural status on health outcomes in pediatric liver transplantation: a single center analysis of 388 patients.

Rural status of patients may impact health before and after pediatric LT. We used UI codes published by the USDA to stratify patients as urban or rural depending county residence. A total of 388 patients who had LT and who met criteria were included. Rejection, PTLD, and survival were used as primary outcome measures of post-LT health. UNOS Status 1 and PELD/MELD scores >20 were used as secondary outcome measures of poorer pre-LT health. Logistic regression models were run to determine associations. We did not find any statistically significant differences in pre- or post-LT outcomes with respect to rurality. Among rural patients, there was a general trend for decreased incidence of rejection (25.0% vs. 33.4%; OR 0.64, 95% CI 0.29-1.44), increased risk of PTLD (5.6% vs. 3.4%; OR 1.86, 95% CI 0.36-3.31), and decreased survival (OR 0.85, 95% CI 0.34-2.13) after LT. Rural patients also tended to be sicker at the time of LT than patients from urban areas, with increased proportion of Status 1 (OR 1.17, 95% CI 0.51-2.70) and PELD/MELD scores >20 (OR 1.20, 95% CI 0.59-2.45). From a single center experience, we conclude that rurality did not significantly affect health outcomes after LT, although a larger study may validate the general trends that rural patients may have decreased rejection, increased PTLD, and mortality, and be in poorer health at the time of LT.

Three dimensional intensity modulated brachytherapy (IMBT): dosimetry algorithm and inverse treatment planning.

PURPOSE: The feasibility of intensity modulated brachytherapy (IMBT) to improve dose conformity for irregularly shaped targets has been previously investigated by researchers by means of using partially shielded sources. However, partial shielding does not fully explore the potential of IMBT. The goal of this study is to introduce the concept of three dimensional (3D) intensity modulated brachytherapy and solve two fundamental issues regarding the application of 3D IMBT treatment planning: The dose calculation algorithm and the inverse treatment planning method. METHODS: A 3D IMBT treatment planning system prototype was developed using the MATLAB platform. This system consists of three major components: (1) A comprehensive IMBT source calibration method with dosimetric inputs from Monte Carlo (EGSnrc) simulations; (2) a "modified TG-43" (mTG-43) dose calculation formalism for IMBT dosimetry; and (3) a physical constraint based inverse IMBT treatment planning platform utilizing a simulated annealing optimization algorithm. The model S700 Axxent electronic brachytherapy source developed by Xoft, Inc. (Fremont, CA), was simulated in this application. Ten intracavitary accelerated partial breast irradiation (APBI) cases were studied. For each case, an "isotropic plan" with only optimized source dwell time and a fully optimized IMBT plan were generated and compared to the original plan in various dosimetric aspects, such as the plan quality, planning, and delivery time. The issue of the mechanical complexity of the IMBT applicator is not addressed in this study. RESULTS: IMBT approaches showed superior plan quality compared to the original plans and tht isotropic plans to different extents in all studied cases. An extremely difficult case with a small breast and a small distance to the ribs and skin, the IMBT plan minimized the high dose volume V200 by 16.1% and 4.8%, respectively, compared to the original and the isotropic plans. The conformity index for the target was increased by 0.13 and 0.04, respectively. The maximum dose to the skin was reduced by 56 and 28 cGy, respectively, per fraction. Also, the maximum dose to the ribs was reduced by 104 and 96 cGy, respectively, per fraction. The mean dose to the ipsilateral and contralateral breasts and lungs were also slightly reduced by the IMBT plan. The limitations of IMBT are the longer planning and delivery time. The IMBT plan took around 2 h to optimize, while the isotropic plan optimization could reach the global minimum within 5 min. The delivery time for the IMBT plan is typically four to six times longer than the corresponding isotropic plan. CONCLUSIONS: In this study, a dosimetry method for IMBT sources was proposed and an inverse treatment planning system prototype for IMBT was developed. The improvement of plan quality by 3D IMBT was demonstrated using ten APBI case studies. Faster computers and higher output of the source can further reduce plan optimization and delivery time, respectively.

Novel low-kVp beamlet system for choroidal melanoma.

BACKGROUND: Treatment of choroidal melanoma with radiation often involves placement of customized brachytherapy eye-plaques. However, the dosimetric properties inherent in source-based radiotherapy preclude facile dose optimization to critical ocular structures. Consequently, we have constructed a novel system for utilizing small beam low-energy radiation delivery, the Beamlet Low-kVp X-ray, or "BLOKX" system. This technique relies on an isocentric rotational approach to deliver dose to target volumes within the eye, while potentially sparing normal structures. METHODS: Monte Carlo N-Particle (MCNP) transport code version 5.0(14) was used to simulate photon interaction with normal and tumor tissues within modeled right eye phantoms. Five modeled dome-shaped tumors with a diameter and apical height of 8 mm and 6 mm, respectively, were simulated distinct positions with respect to the macula iteratively. A single fixed 9 x 9 mm2 beamlet, and a comparison COMS protocol plaque containing eight I-125 seeds (apparent activity of 8 mCi) placed on the scleral surface of the eye adjacent to the tumor, were utilized to determine dosimetric parameters at tumor and adjacent tissues. After MCNP simulation, comparison of dose distribution at each of the 5 tumor positions for each modality (BLOKX vs. eye-plaque) was performed. RESULTS: Tumor-base doses ranged from 87.1-102.8 Gy for the BLOKX procedure, and from 335.3-338.6 Gy for the eye-plaque procedure. A reduction of dose of at least 69% to tumor base was noted when using the BLOKX. The BLOKX technique showed a significant reduction of dose, 89.8%, to the macula compared to the episcleral plaque. A minimum 71.0 % decrease in dose to the optic nerve occurred when the BLOKX was used. CONCLUSION: The BLOKX technique allows more favorable dose distribution in comparison to standard COMS brachytherapy, as simulated using a Monte Carlo iterative mathematical modeling. Future series to determine clinical utility of such an approach are warranted.

El Programa de Reforma del Estado en Costa Rica / Programme of state reform in Costa Rica

Los cambios radicales que se están produciendo en el mundo, en el campo económico, político y social, propician la globalización de las economías y la formación de bloques de poder. Estos cambios han generado un nuevo orden internacional, que demandarían de los países en vías de desarrollo la transformación del aparato del Estado, de forma que la organización estatal sea ágil, flexible y eficiente a partir de la concepción de un Estado Moderno que fortalezca la estructura democrática del país. Para ello se requiere impulsar procesos de descentralización de las actividades que cumple el Estado, fortaleciendo la regionalización, de manera que la planificación tenga una proyección en el territorio nacional y así abandonar su concepción centralista. Tal es el panorama que presenta el Programa de Reforma del Estado Costarricense, cuyos lineamientos han ido planteados ante los organismos que manejan la política económica internaciona, como es el caso del Fondo Monetario (FMI). Sin embargo, cuando se producen cambios, surgen inevitablemente ganadores y perdedores. Identificar los grupos o actores que se beneficiarían del mismo parece ser una tarea de análisis positiva, que nos permitiría conocer los beneficios que le generaría a la colectividad nacional, una propuesta de cambio de esta naturaleza. El propósito de este ensayo va en esta vía. Conocer la direccionalidad de la propuesta e intentar explicarla

Hepatic artery thrombosis following pediatric liver transplantation: Assessment of blood flow measurement in allografts.

The purpose of this study was to define parameters which could be predictive of hepatic artery thrombosis, which continues to be a major complicating factor in pediatric liver transplantation. The hepatic blood flow of 14 pediatric liver patients (15 grafts) who weighed less than 15 kg was measured electromagnetically during orthotopic liver transplantation. The results of blood flow determination and the clinical data in 7 patients (8 grafts) who developed hepatic artery thrombosis were compared with those of 7 control patients. All patients with a hepatic arterial flow of less than 60 ml/min developed hepatic artery thrombosis (4/8 vs. 0/7; p < 0.05), and the patients with hepatic artery thrombosis exhibited higher total hepatic and portal vein flow per 100 gram of liver tissue (262 vs. 136 ml/min; p < 0.001 and 222 vs. 80 ml/min; p < 0.025, respectively) as well as longer cold preservation time (384 vs. 326 min; p < 0.025). The results of our study suggest that hepatic arterial flows of less than 60 ml/min are critical for the development of hepatic artery thrombosis, and that portal venous overflow and increased preservation times may contribute to the development of hepatic artery thrombosis.