Transrectal ultrasound for intraoperative interstitial needle guidance in cervical cancer brachytherapy.

OBJECTIVE: This study aimed to prospectively assess the visibility of interstitial needles on transrectal ultrasound (TRUS) in cervical cancer brachytherapy patients and evaluate its impact on implant and treatment plan quality. MATERIAL AND METHODS: TRUS was utilized during and after applicator insertion, with each needle's visibility documented through axial images at the high-risk clinical target volume's largest diameter. Needle visibility on TRUS was scored from 0 (no visibility) to 3 (excellent discrimination, margins distinct). Quantitative assessment involved measuring the distance between tandem and each needle on TRUS and comparing it to respective magnetic resonance imaging (MRI) measurements. Expected treatment plan quality based on TRUS images was rated from 1 (meeting all planning objectives) to 4 (violation of High-risk clinical target volume (CTVHR) and/or organ at risk (OAR) hard constraints) and compared to the final MRI-based plan. RESULTS: Analysis included 23 patients with local FIGO stage IB2-IVA, comprising 41 applications with a total of 230 needles. A high visibility rate of 99.1% (228/230 needles) was observed, with a mean visibility score of 2.5 ±â€¯0.7 for visible needles. The maximum and mean difference between MRI and TRUS measurements were 8 mm and -0.1 ±â€¯1.6 mm, respectively, with > 3 mm discrepancies in 3.5% of needles. Expected treatment plan quality after TRUS assessment exactly aligned with the final MRI plan in 28 out of 41 applications with only minor deviations in all other cases. CONCLUSION: Real-time TRUS-guided interstitial needle placement yielded high-quality implants, thanks to excellent needle visibility during insertion. This supports the potential of TRUS-guided brachytherapy as a promising modality for gynecological indications.

[Image-based computer diagnosis of melanoma]. / Bildbasierte Computerdiagnose des Melanoms.

The use of automated diagnostic systems for the diagnosis of melanomas is becoming increasingly more established. These are based on the following four steps: 1) preprocessing, to ensure that disturbing factors are eliminated, 2) segmentation, the separation of the image and the background, 3) extraction and selection of features that provide the highest measure of accuracy for the diagnosis and 4) classification, in which the lesion is assigned to a diagnostic class. Recently, the computer-assisted diagnosis of melanoma has focused on algorithms based on transfer learning, which can make steps 2 and 3 obsolete and provides better results. In this article we also review smartphone applications in the field of melanoma screening and recognition. These applications should be considered with caution as they are available to lay persons although the diagnostic accuracy of these applications has not usually been tested in clinical trials.

Tuberculosis relapse in Vietnam is significantly associated with Mycobacterium tuberculosis Beijing genotype infections.

BACKGROUND: In Vietnam, the Mycobacterium tuberculosis Beijing genotype is associated with multi-drug resistance and is emerging. A possible explanation for this genotype's success is an increased rate of relapse. METHODS: In a prospective cohort study, isolates from patients with smear-positive tuberculosis were subjected to drug susceptibility testing and to spoligotyping and variable number of tandem repeats typing before treatment and after recurrence of tuberculosis. RESULTS: Among 1068 patients who were actively followed up over 18 months for recurrence, 23 relapse cases occurred (1.39 cases/100 person-years). After adjustment for genotype, tuberculosis treatment history, and drug resistance, relapse was significantly associated with the Beijing genotype (adjusted hazard ratio [aHR], 5.48; 95% confidence interval [CI], 2.06-14.55) and isoniazid resistance (aHR, 5.91; 95% CI, 2.16-16.16). CONCLUSIONS: The strongly increased relapse rate in tuberculosis cases caused by Beijing strains probably contributes to the successful spread of this genotype in Vietnam and elsewhere.

Features in coherent transmittance of a monolayer of particles.

Coherent and incoherent transmittance values of a monolayer of particles are considered. Such a monolayer is a set of particles whose centers are located in the same plane. We set forth the conditions for the effect of coherent-transmittance quenching, which takes place as a result of the interference between incident and forward-scattered waves. Using the single-scattering approximation we determined size parameters and particle refractive indexes for this interference effect in the case of identical isotropic spherical particles. The influence of polydispersity and the fine structure of light-scattering characteristics on the quenching effect has been estimated. It is shown that the polydispersity destroys this interference effect only at large widths of particle-size distribution functions. The influence of multiple scattering on this effect is considered in the quasi-crystalline approximation. Multiple scattering results in increasing size parameters and decreasing particle concentration at which coherent transmittance quenching takes place in comparison with the case of single scattering. Our theoretical results for suspensions of latex particles in water are in fairly good agreement with the experimental results.

Passage of light through a dispersion medium with a high concentration of discrete inhomogeneities: experiment.

The passage of light through dispersion layers consisting of large weakly absorbing scatterers has been investigated. Measurements of the transmittance and the angular structure of scattered radiation have been made. The dependence of these characteristics on the thickness and the concentration of scatterers has been analyzed.

Applicability Limits of Beer's Law for Dispersion Media with a High Concentration of Particles.

This study analyzes the values of volume concentrations of scatterers at which radiation extinction in dispersion media obeys Beer's law. The dependence of the maximum particle concentration at which Beer's law holds on the properties of the dispersion medium is investigated. It is shown that the maximum concentration is strongly dependent on the scatterers' parameters and varies over a wide range, from tenths to tens of percent.

Light transmission by a monolayer of particles: comparison of experimental data with calculation as a single-scattering approximation.

The laws of light transmission by particle monolayers are investigated. The results of measurement of coherent transmission for monolayers formed by large nonabsorbing particles are presented. The obtained results are compared to the calculation in the single-scattering approximation. Good agreement between experimental and calculated data is shown.

Angular structure of radiation scattered by monolayers of particles: experimental study.

An experimental study has been made of the angular structure of radiation scattered by monolayers of large nonabsorbing particles. We have investigated three media exhibiting different light-scattering properties: monodisperse polyvinyl toluene latex particles of 3.75-mum diameter suspended in water, polydisperse rice starch particles with a mean diameter of 6.4 mum suspended in water, and a mixture of ethyl and benzoic alcohols. It is shown that for large particles the structure of scattered radiation can be described in a single-scattering approximation. Analysis of the influence of polydispersity and the relative refractive index of particles on the intensity scattered by the monolayer has been performed.

[Computer-assisted multimedia interactive learning program "Primary Open-Angle Glaucoma"]. / Das computergestützte multimediale interaktive Lernprogramm "Primäres Offenwinkelglaukom".

INTRODUCTION: Advances in the area of information technology have opened up new possibilities for the use of interactive media in the training of medical students. Classical instructional technologies, such as video, slides, audio cassettes and computer programs with a textbook orientation, have been merged into one multimedia computer system. The medical profession has been increasingly integrating computer-based applications which can be used, for example, for record keeping within a medical practice. The goal of this development is to provide access to all modes of information storage and retrieval as well as documentation and training systems within a specific context. MATERIAL AND METHODS: Since the beginning of the winter semester 1995, the Department of Ophthalmology in Giessen has used the learning program "Primary Open Angle Glaucoma" in student instruction. One factor that contributed to the implementation of this project was that actual training using patients within the clinic is difficult to conduct. Media-supported training that can provide a simulation of actual practice offers a suitable substitute. The learning program has been installed on Power PCs (Apple MacIntosh), which make up the technical foundation of our system. The program was developed using Hypercard software, which provides userfriendly graphical work environment. This controls the input and retrieval of data, direct editing of documents, immediate simulation, the creation of on-screen documents and the integration of slides that have been scanned in as well as QuickTime films. All of this can be accomplished without any special knowledge of programming language or operating systems on the part of the user. RESULTS: The glaucoma learning program is structured along the lines of anatomy, including an explanation of the circulation of the aqueous humor, pathology, clinical symptoms and findings, diagnosis and treatment. This structure along with the possibility for creating a list of personal files for the user with a collection of illustrations and text allows for quick access to learning content. The program is designed in such a way that working with and through it is done in a manner conducive to learning. Student response to the learning program as an accompaniment to instruction has been positive. CONCLUSION: Independent, supplemental student learning by means of an interactive learning program has raised the quality of study within the sciences. The use of a pedagogically sound multimedia program, that is oriented toward problem solving and based on actual cases offers students the opportunity to actively work ophthalmological material. An additional benefit is the development of competence in working with computer-support information systems, something that is playing an ever-increasing role within the medical profession.

Safety of the bolus administration of gentamicin.

A study was done to assess the safety of gentamicin administration by a bolus method. A total of 63 patients were randomly treated with intravenous gentamicin by bolus administration (3 to 5 min) and by slow infusion (2 h). Serum gentamicin levels were measured. Renal and audiovestibular function were monitored. Pure-tone audiometry was performed at the beginning, on day 3, and at the end of therapy. The study revealed that the bolus administration was safe and nontoxic.

Pharmacology of cephalothin in the biliary tract of humans.

Serum and biliary tract levels of cephalothin were determined in a large series of patients. Serum cephalothin levels in the therapeutic range were present at 1 h after a single dose of the antibiotic in only 4 of 39 (10.3%) subjects. Therapeutic bile cephalothin levels were achieved in only 2.4% of all subjects, and this occurred between 40 and 70 min after the administration of the antibiotic.