PURPOSE: High intensity focused ultrasound (HIFU) provides a non-invasive salvage treatment option for patients with recurrence after external beam radiation therapy (EBRT). As part of EBRT the prostate is frequently implanted with permanent fiducial markers. To date, the impact of these markers on subsequent HIFU treatment is unknown. The objective of this work was to systematically investigate, using computational simulations, how these fiducial markers affect the delivery of HIFU treatment. METHODS: A series of simulations was performed modelling the propagation of ultrasound pressure waves in the prostate with a single spherical or cylindrical gold marker at different positions and orientations. For each marker configuration, a set of metrics (spatial-peak temporal-average intensity, focus shift, focal volume) was evaluated to quantify the distortion introduced at the focus. An analytical model was also developed describing the marker effect on the intensity at the focus. The model was used to examine the marker's impact in a clinical setting through case studies. RESULTS: The simulations show that the presence of the marker in the pre-focal region causes reflections which induce a decrease in the focal intensity and focal volume, and a shift of the maximum pressure point away from the transducer's focus. These effects depend on the shape and orientation of the marker and become more pronounced as its distance from the transducer's focus decreases, with the distortion introduced by the marker greatly increasing when placed within 5 mm of the focus. The analytical model approximates the marker's effect and can be used as an alternative method to the computationally intensive and time consuming simulations for quickly estimating the intensity at the focus. A retrospective review of a small patient cohort selected for focal HIFU after failed EBRT indicates that the presence of the marker may affect HIFU treatment delivery. CONCLUSIONS: The distortion introduced by the marker to the HIFU beam when positioned close to the focus may result in an undertreated region beyond the marker due to less energy arriving at the focus, and an overtreated region due to reflections. Further work is necessary to investigate whether the results presented here justify the revision of the patient selection criteria or the markers' placement protocol.

• MeSH
• Artifacts * MeSH
• Humans MeSH
• Prostatic Neoplasms therapy   MeSH
• Ultrasound, High-Intensity Focused, Transrectal standards   MeSH
• Salvage Therapy standards   MeSH
• Fiducial Markers * MeSH
• Gold * MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH

Úvod: Cílem tohoto článku je na základě 3D CT rekonstrukcí popsat anatomii zlomenin dolního úhlu a přilehlé části těla lopatky. Metoda: V souboru 375 zlomenin lopatky jsme identifikovali celkem 20 zlomenin dolního úhlu těla lopatky (13 mužů, 7 žen), průměrného věku 50 let (33−73 roků). U všech zlomenin byly provedeny 3D CT rekonstrukce umožňující objektivní zhodnocení typu zlomeniny. Sledovali jsme velikost a tvar fragmentu dolního úhlu, propagaci lomné linie do laterálního a mediálního okraje infraspinátní části těla lopatky, dislokaci úlomků případné další zlomeniny stejné lopatky a ramenního pletence. Výsledky: Identifikovali jsme celkem 5 typů zlomenin postihujících distální polovinu infraspinální části těla. První typ, který jsme zaznamenali v 5 případech, postihoval pouze apex dolního úhlu s malou částí přilehlého mediálního okraje. Druhý typ představovaly zlomeniny oddělující celý dolní úhel. Identifikovány byly 4 případy. Třetí typ, zastoupený 4 případy, byl charakterizován lomnou linií začínající mediální těsně nad dolním úhlem a směřující proximolaterálně. Odlomený fragment tak získal podobu velké kapky, která kromě dolního úhlu nesla distální polovinu laterálního pilíře. U čtvrtého typu tvořil odlomený fragment nejen dolní úhel, ale i variabilní část mediálního okraje. Zaznamenáno bylo 5 zlomenin. Pátý typ představoval přechod ke zlomenině infraspinátní části těla. Ve 2 zaznamenaných případech byl tvar fragmentu stejný, tj. měl tvar písmena „V“. Závěr: Zlomeniny dolního úhlu a přilehlé části těla lopatky představují skupiny zlomenin odlišnou od ostatních infraspinátních zlomenin těla lopatky. Ačkoli zlomeniny dolního úhlu vykazují značnou tvarovou variabilitu, spojuje je průběh lomné linie v laterálním okraji těla a způsob dislokace.

Introduction: The aim of this study is to describe the anatomy of fractures of the inferior angle and the adjacent part of the scapular body, based on 3D CT reconstructions. Method: In a series of 375 scapular fractures, we identified a total of 20 fractures of the inferior angle of the scapular body (13 men, 7 women), with a mean patient age of 50 years (range 33−73). In all fractures, 3D CT reconstructions were obtained, allowing an objective evaluation of the fracture pattern with a focus on the size and shape of the inferior angle fragment, propagation of the fracture line to the lateral and medial borders of the infraspinous part of the scapular body, fragment displacement and any additional fracture of the ipsilateral scapula and the shoulder girdle. Results: We identified a total of 5 types of fracture involving the distal half of the infraspinous part of the scapular body. The first type, recorded in 5 cases, affected only the apex of the inferior angle, with a small part of the adjacent medial border. The second type, occurring in 4 cases, involved fractures separating the entire inferior angle. The third type, represented by 4 cases, was characterized by a fracture line starting medially close above the inferior angle and passing proximolaterally. The separated fragment had a shape of a big drop, carrying also the distal half of the lateral pillar in addition to the inferior angle. In the fourth type identified in 5 fractures, the separated fragment was formed both by the inferior angle and a variable part of the medial border. The fifth type, being by its nature a transition to the fracture of the infraspinous part of the body, was recorded in 2 cases, with the same V-shaped fragment. Conclusion: Fractures of the inferior angle and the adjacent part of the scapular body are groups of fractures differing from other infraspinous fractures of the scapular body. Although these fractures are highly variable in terms of shape, they have the same course of fracture line and the manner of displacement.

• MeSH
• Joint Dislocations diagnosis   surgery   MeSH
• Fracture Fixation MeSH
• Fractures, Bone * surgery   classification   MeSH
• Humans MeSH
• Scapula * anatomy & histology   diagnostic imaging   injuries   MeSH
• Orthopedic Procedures MeSH
• Tomography, X-Ray Computed MeSH
• Fracture Fixation, Internal MeSH
• Imaging, Three-Dimensional MeSH
• Check Tag
• Humans MeSH

Úvod: Cílem tohoto článku je na základě 3D CT rekonstrukcí 187 zlomenin těla lopatky navrhnout klinicky orientovanou klasifikaci zlomenin těla respektující biomechanickou stavbu lopatky. Metody: V souboru 375 zlomenin lopatky jsme identifikovali celkem 187 zlomenin těla lopatky u 187 pacientů (157 mužů, 30 žen), průměrného věku 48 roků (range; 16−100 roků). U všech zlomenin byly provedeny 3D CT rekonstrukce umožňující objektivní zhodnocení typu zlomeniny. Operováno bylo 46 pacientů, což umožnilo korelovat peroperační nález s 3D CT rekonstrukcemi. Za zlomeniny těla jsme považovali pouze ty zlomeniny, které procházely biomechanickým tělem lopatky, tj. porušovaly alespoň jeden z pilířů. Nepatřily sem proto zlomeniny horního úhlu a horního okraje těla lopatky, neboť se jednalo o okrajové zlomeniny, které ponechávají oba pilíře intaktní. Exkludovali jsme i zlomeniny krčku lopatky, které jsou definovány jako extraartikulární dvoufragmentové zlomeniny laterálního úhlu lopatky oddělující glenoid od těla lopatky. Vyřadili jsme i zlomeniny dolního úhlu lopatky. Hodnotili jsme průběh lomných linií, jejich vztah k oběma pilířům lopatky, a počet fragmentů. Jako samostatný fragment byl hodnocen pouze takový úlomek, který nesl část obvodu biomechanického těla. Tzn., že nebyly započítány interkalární fragmenty vylomené z centrální části fossa infraspinata. Výsledky: Identifikovali jsme tři základní skupiny zlomenin těla, tj. zlomeniny postihující pouze spinální pilíř, zlomeniny postihující pouze laterální pilíř a zlomeniny obou pilířů. Zlomeniny spinózního pilíře jsme zaznamenali 12krát. V 8 případech probíhala hlavní lomná linie vertikálně ze supraspinátní jámy centrální částí spinálního pilíře směrem do mediálního okraje infraspinátní fossy. Ve 4 případech byla baze spina scapulae vylomena z těla lopatky. Laterální pilíř zůstal ve všech případech neporušen a dislokace fragmentů byla vždy malá, takže všechny zlomeniny byly léčeny konzervativně. Zlomeniny laterálního pilíře se vyskytly ve 143 případech. Vždy šlo o zlomeninu infraspinátní části těla lopatky tj. infraspinátní jámy, kdy hlavní lomná linie vycházela z laterálního pilíře. Tento typ zlomeniny jsme na základě počtu obvodových úlomků rozdělili na další tři subtypy, tj. dvou-fragmentové (88 zlomenin), tří-fragmentové (31 zlomenin) a kominutivní (24 zlomenin). Zlomenina obou pilířů byla zjištěna ve 32 případech. Tato zlomenina se vyskytovala ve dvou formách. V první skupině (11 zlomenin) probíhala lomná linie spinózním pilířem v těsné blízkosti spinomediálního úhlu do horního úhlu lopatky. Ve druhé skupině (21 zlomenin) procházela hlavní lomná linie centrálním zeslabením spina scapulae. Tento kominutivní typ zlomeniny představoval nejzávažnější poranění těla lopatky. Lomná linie procházela vždy zeslabenou centrální částí spinózního pilíře. Zlomenina laterálního pilíře byla dislokována ve všech případech více než zlomenina pilíře spinózního. Závěr: Klasifikace zlomenin těla lopatky na základě postižení pilířů těla lopatky a je logická a jednoduchá. Vyžaduje 3D CT rekonstrukce včetně subtrakce okolních kostí. Respektuje anatomickou stavbu lopatky a může sloužit i jako terapeutické vodítko při plánování operační léčby.

Introduction: The aim of this study is to present, on the basis of 3D CT reconstructions of 187 of scapular body fractures, a clinically oriented classification respecting the biomechanical architecture of the scapula. Methods: In a series of 375 scapula fractures we identified 187 body fractures in187 patients (157 men, 30 women) with the mean age of 48 years (range; 16−100 years). 3D CT reconstructions were obtainedof all fractures, to allow an objective evaluation of the fracture pattern. A total of 46 patients were operated on and their intraoperative findings were correlated with 3D CT reconstructions. Scapular body fractures were deemed to be only those fractures that passed through the biomechanical body of the scapula, i.e. involved at least one of the pillars. Excluded from the study were fractures of the superior angle and of the superior border of the scapula as they were only marginal fractures leaving both pillars intact; scapular neck fractures defined as extra-articular two-part fractures of the lateral angle separating the glenoid from the scapular body; and fractures of the inferior angle of the scapula. Evaluation focused on the course of fracture lines, their relationship to the two pillars, and the number of fragments. A separate fragment was considered to be only such a fragment that carried part of the circumference of the biomechanical body. The intercalary fragmentsbroken off the central part of the infraspinous fossa were not included. Results: We identified three basic groups of scapular body fractures, i.e. those involving only the spinal pillar, those involving only the lateral pillar and fractures affecting both pillars. Our series included 12 fractures of the spinal pillar, of these in 8 cases the main fracture line passed vertically from the supraspinous fossa of the central part of the pillar toward the medial border of the infraspinous fossa; in 4 cases the scapular spine base was broken off the scapular body. In all the cases, the lateral pillar was left intact and fragments were displaced only insignificantly. Therefore all these fractures were treated non-operatively. A total of 143 fractures involved the lateral pillar. All of them were fractures of the infraspinous portion of the scapular body, i.e. the infraspinous fossa, with the main fracture line propagating from the lateral pillar. This fracture pattern was divided on the basis of the number of circumference fragments into three subtypes, namely two-part (88), three-part (31) and comminuted (24) fractures. Fractures of both pillars were recorded in 32 cases. This fracture had two patterns, one (11 fractures) with a fracture line running through the spinal pillar close to the spinomedial angle to the superior angle of the scapula, and the other (21 fractures) with the main fracture line passing through the weakened central part of the scapular spine. This comminuted type was the most severe injury to the scapular body. The fracture line always propagated through the weakened central part of the spinal pillar. The fracture of the lateral pillar was displaced in all cases more than that of the spinal pillar. Conclusion: Classification of scapular body fractures based on involvement of the pillars of the scapular body is logical and simple. It always requires a 3D CT reconstruction, including subtraction of the surrounding bones. It respects the anatomical structure of the scapula and may serve also as a therapeutic guidance in preoperative planning.

• MeSH
• Joint Dislocations diagnosis   surgery   MeSH
• Fracture Fixation MeSH
• Fractures, Bone * surgery   classification   MeSH
• Humans MeSH
• Scapula * anatomy & histology   diagnostic imaging   injuries   MeSH
• Orthopedic Procedures methods   MeSH
• Tomography, X-Ray Computed MeSH
• Retrospective Studies MeSH
• Fracture Fixation, Internal MeSH
• Imaging, Three-Dimensional MeSH
• Check Tag
• Humans MeSH

• MeSH
• Image Interpretation, Computer-Assisted MeSH

• Conspectus
• Lékařské vědy. Lékařství
• NML Fields
• lékařská informatika

OBJECTIVES: Ultra-high-speed (UHS) videography was used to visualize the fracture phenomena at the resin-dentin interface during micro-tensile bond strength (μTBS) test. We also investigated whether UHS videography is applicable for failure-mode analysis. METHODS: Ten human mid-coronal dentin surfaces were bonded using Clearfil SE Bond either in self-etching (SE) or etch-and-rinse (ER) mode. After 24-h water storage, the samples were cut into beams for μTBS test and tested at a cross-head speed of 1 mm/min. The fracture phenomena at the bonded interface were captured using a complementary metal-oxide-semiconductor digital UHS camera at 299,166 frames per second. The failure modes were classified using UHS videography, followed by scanning electron microscopy (SEM) analysis. The failure-mode distributions determined by UHS videography and SEM analysis were statistically analyzed using Fisher's exact test with Bonferroni correction. RESULTS: The crack-propagation speed exceeded 1,500 km/h. No significant difference was found between the SEM and UHS videography failure-mode distributions in the SE mode. A significant difference appeared between them in the ER mode. Significant differences in the incidence of cohesive failures within the adhesive and at the adhesive-composite interface between the SE and ER modes were identified by both SEM and UHS videography. SIGNIFICANCE: UHS videography enabled visualization of the fracture dynamics at the resin- dentin interfaces under tensile load. However, the resolution at such high frame rate was insufficient to classify the failure mode as precisely as that of SEM. Nevertheless, UHS videography can provide more detailed information about the fracture origin and propagation.

• MeSH
• Dentin MeSH
• Dentin-Bonding Agents * MeSH
• Humans MeSH
• Stress, Mechanical MeSH
• Microscopy, Electron, Scanning MeSH
• Tensile Strength MeSH
• Surface Properties MeSH
• Resin Cements MeSH
• Composite Resins MeSH
• Materials Testing MeSH
• Dental Bonding * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Experimental and theoretical foundations for femtosecond time-resolved circular dichroism (TRCD) spectroscopy of excitonic systems are presented. In this method, the system is pumped with linearly polarized light and the signal is defined as the difference between the transient absorption spectrum probed with left and with right circularly polarized light. We present a new experimental setup with a polarization grating as key element to generate circularly polarized pulses. Herein the positive (negative) first order of the diffracted light is left-(right-)circularly polarized and serves as a probe pulse in a TRCD experiment. The grating is capable of transferring ultrashort broadband pulses ranging from 470 nm to 720 nm into two separate beams with opposite ellipticity. By applying a specific chopping scheme we can switch between left and right circular polarizations and detect transient absorption (TA) and TRCD spectra on a shot-to-shot basis simultaneously. We perform experiments on a squaraine polymer, investigating excitonic dynamics, and we develop a general theory for TRCD experiments of excitonically coupled systems that we then apply to describe the experimental data in this particular example. At a magic angle of 54.7° between the pump-pulse polarization and the propagation direction of the probe pulse, the TRCD and TA signals become particularly simple to analyze, since the orientational average over random orientations of complexes factorizes into that of the interaction with the pump and the probe pulse, and the intrinsic electric quadrupole contributions to the TRCD signal average to zero for isotropic samples. Application of exciton theory to linear absorption and to linear circular dichroism spectra of squaraine polymers reveals the presence of two fractions of polymer conformations, a dominant helical conformation with close interpigment distances that are suggested to lead to short-range contributions to site energy shifts and excitonic couplings of the squaraine molecules, and a fraction of unfolded random coils. Theory demonstrates that TRCD spectra of selectively excited helices can resolve state populations that are practically invisible in TA spectroscopy due to the small dipole strength of these states. A qualitative interpretation of TRCD and TA spectra in the spectral window investigated experimentally is offered. The 1 ps time component found in these spectra is related to the slow part of exciton relaxation obtained between states of the helix in the low-energy half of the exciton manifold. The dominant 140 ps time constant reflects the decay of excited states to the electronic ground state.

• Publication type
• Journal Article MeSH

Experimental radiobiological studies in which the effects of ionizing radiation on a biological model are examined often highlight the biological aspects while missing detailed descriptions of the geometry, sample and dosimetric methods used. Such omissions can hinder the reproducibility and comparability of the experimental data. An application based on the Geant4 simulation toolkit was developed to design experiments using a biological solution placed in a microtube. The application was used to demonstrate the influence of the type of microtube, sample volume and energy of a proton source on the dose distribution across the sample, and on the mean dose in the whole sample. The results shown here are for samples represented by liquid water in the 0.4-, 1.5- and 2.0-ml microtubes irradiated with 20, 30 and 100 MeV proton beams. The results of this work demonstrate that the mean dose and homogeneity of the dose distribution within the sample strongly depend on all three parameters. Furthermore, this work shows how the dose uncertainty propagates into the scored primary DNA damages in plasmid DNA studies using agarose gel electrophoresis. This application is provided freely to assist users in verifying their experimental setup prior to the experiment.

• MeSH
• Models, Biological MeSH
• Radiation Dosage * MeSH
• Electrophoresis, Agar Gel MeSH
• Radiation, Ionizing MeSH
• Uncertainty MeSH
• Plasmids MeSH
• DNA Damage MeSH
• Protons MeSH
• Radiometry methods   MeSH
• Reproducibility of Results MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

• MeSH
• Allergy and Immunology MeSH
• Immune System MeSH
• Publication type
• Textbook MeSH

• Conspectus
• Patologie. Klinická medicína
• Učební osnovy. Vyučovací předměty. Učebnice
• NML Fields
• alergologie a imunologie