Absolute measurement of surface particle emission rates from α and β plane sources using a digitizer / 中国辐射卫生

Objective@#To prove the validity and accuracy of the digitizer instead of the conventional electronics plug-in for radionuclide measurement.@*Methods@# Based on a large-area flow-gas multi-wire proportional counter for 2πα and 2πβ surface particle emission rate measurement, the DT5730 digital waveform sampler developed by CAEN was used for waveform signal acquisition, amplitude analysis, and data processing of the α-plane source 241Am and the β-plane source nuclides 14C, 36Cl, and 90Sr-90Y of different energies.@*Results@#The deviations between the α and β surface particle emission rate results obtained after dead time and background corrections and the measurements obtained based on the plug-in calibrator were all within 0.6%, within the uncertainty range, under consistent experimental conditions such as electronics threshold and high pressure.@*Conclusion@#The digitizer is an effective alternative to conventional electronics plug-ins for α and β signal acquisition and processing and the accurate measurement of α and β emission rates.

Sistema de adquisición de datos en tiempo real para un detector modular de neutrones en los experimentos con el RIBRAS / A real time pulse processing Data acquisition for neutron modular detector on RIBRAS experiments

Resumen Con la finalidad de maximizar las posibilidades experimentales en el estudio de los núcleos exóticos utilizando el haz del sistema "Radioactive Ion Beams in Brasil" (RIBRAS), fue desarrollado un sistema modular de detectores centelleantes orgánicos con buena eficiencia y amplio ángulo sólido, conocido como Pared de Neutrones. La detección de los neutrones emitidos en coincidencia con los fragmentos de reacción incrementa las posibilidades experimentales y constituye una de las técnicas más usadas en el campo de la Astrofísica Nuclear. El obsoleto sistema de adquisición de datos de la Pared de Neutrones debe ser remplazado por un sistema basado en módulos del patrón Versa Module Euro Card (VME). El nuevo esquema será definido para incluir el arreglo de detectores de bandas para partículas cargadas y la Pared de Neutrones con el máximo de eficiencia de adquisición, sin tiempo muerto, con selección de datos y sincronización de eventos. Los módulos digitalizadores garantizan tareas como la supresión de ceros y la saturación en la lectura de la señal. Adicionando tarjetas FPGA (field programmable gate array) a la adquisición de datos se garantiza el procesamiento pre y post-algorítmico de los datos.

Abstract In order to potentiate the experiments for studying the exotic nuclei with Brazil Radioactive Ion Beam (RIBRAS), a modular organic scintillation detector (Neutron Wall), with good efficiency and extended solid angle was developed. The detection of neutrons emitted in coincidence with the reaction fragments increases the experimental possibilities and represents one of the most popular techniques in the Nuclear Astrophysics field. The data acquisition system used for the Neutron Wall is obsolete and should be replaced by Versa Module Euro Card Data Acquisition modules. The new scheme will be designed to include the Strip Array and Neutron Wall detectors with maximum readout efficiency, no dead time, data selection and event synchronization. The digitizer modules provide features like zero suppressed readout and overflow suppression. Zero suppression, once enabled, prevents conversion of value, which is lower than user defined threshold. Adding FPGA (field programmable gate array) cards to data acquisition provides pre- and post-algorithmic processing on data.

Manikin Model Study on Reproducibility and Accuracy of Maxillofacial Measurements Determined by Stereocamera: Comparative Study of Direct Anthropometry, Digitizer and Stereophotogrammetery

Accuracy of stone cast produced by adjustable dental impression tray / 대한치과보철학회지

PURPOSE: This study was performed to measure the accuracy of adjustable dental impression trays by a scanning laser three-dimensional digitizer. MATERIALS AND METHODS: The metal stock, individual, and adjustable stock trays were used for 60 stone casts(10 casts each) duplicated a resin master model of mandible and maxilla. The type IV dental stone was poured in a vinyl polysiloxane impressions and allowed to set for one hour. The master model and the duplicated casts were digitized using an optical digitizer. The distance between the reference points were measured and analyzed on the graphic image of 3-D graphic software(CATIA version 5.0). The statistical significance of the differences between the groups was determined by a two-way ANOVA. RESULTS: There were no significant differences between the accuracies of the adjustable stock tray and the master model except only anterior arch width on the upper arch and the diagonal arch length and arch length on one side of the lower arch. CONCLUSION: The adjustable stock trays showed clinically acceptable accuracies of the study cast produced by them.

On the marginal fidelity of all-ceramic core using CAD/CAM system / 대한치과보철학회지

Novel methods producing supplementary and prosthetic material by cutting or discharge processing via computer design have been proposed as alternatives for traditional casting methods and are being utilized for commercial purposes. The CAD/CAM system used in dentistry can be classified into three-dimensional input of target values, restoration design, and material processing. The marginal fidelity in production of In-Ceram core has important clinical implications and is a key consideration issue in CAD/CAM production as well. Through this research, the author arrived at the following conclusion after conducting comparison analysis of marginal fidelities between the In-Ceram core produced via CAD/CAM and that produced through the traditional method: 1. In the cases of mesial, distal, and lingual margins, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 2. In the case of labial flange, the core margins via CAD/CAM produced lower values than those via the traditional method and the differences were found to be statistically significant. (p<0.05) 3. In comparision with overall marginal fidelity, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 4. Among the core margins produced via the traditional method did not have statistically significant differences but for those produced via CAD/CAM had statistically significant differences between labial and lingual sides and between labial and mesial sides. (p<0.05)

Quantitative Assessment on Properties of LASER and CCD-based Film Digitizer / 대한의료정보학회지

Picture archiving and communication systems (PACS) has widely been used in many hospitals. Film digitizer has been used in order to create digital image file from conventional plain radiographic films for PACS. In this study, we quantitatively assessed the characteristics of film digitizer for both laser and CCD camera-based type used in Severance hospital. We created three test films to measure the quality of digitized images. The test films were then digitized by both laser and CCD camera-based film digitizer. Finally, the image files were transferred to the PC in which spatial resolution, contrast, and uniformity were evaluated. We also measured digitization time to evaluate the speed of digitizer. Modulation transfer function (MTF) was measured to evaluate the spatial resolution. Contrast was evaluated by measuring of useful range of optical density (OD). Contrast uniformity was calculated by the percentage of difference between minimum and maximum pixel values on the digitized images. Spatial resolution of laser digitizer was ~~5.0cycles/mm, while that of CCD-based unit was ~~1.5cycles/mm of spatial resolution at 10% of MTF. Useful range of OD for CCD unit was ~~77%, while that for laser unit was 100%. Contrast uniformities of laser unit were better than those of CCD-based unit. Digitization time was ~~10sec/film using CCD unit, and ~~60sec/film using LASER unit at film size of 17x14 inches. Laser digitizer can provide relatively higher image quality, while CCD-based unit has the advantage of higher speed than laser unit.

A Robot Arm-type Navigation System for Pedicle Screw Placement: A Feasibility Study / 대한척추외과학회지

STUDY DESIGN: The study involved the development and accuracy testing of an intra-operative navigation system. OBJECTIVES: This study was undertaken to develop a navigation system using a robot arm-type three-dimensional digitizer. And, to apply the developed system to pedicle screw insertion, and to evaluate its accuracy. SUMMARY OF LITERATURE REVIEW: To the best of our knowledge, no navigation system has been developed using a robot armtype three-dimensional digitizer. MATERIALS AND METHODS: We have developed a navigator using a three-dimensional digitizer (Microscribe 3-D G2, Immersion, USA) supported by a personal computer. Four types of patient-to-image registration techniques were implemented. During navigation, the central axis of the robot arm's stylus and arm extension can be displayed over multi-planar and three-dimensional images, which are reconstructed from axial CT scan images. Registration errors and target localization errors of the navigation system were evaluated using a phantom made from a plastic lumbo-sacral bone model. The accuracy of pedicle screw insertion was also evaluated by placing 18 pedicle screws in such bone models. RESULTS: The registration error was 0.78 +/- 0.27 mm at fiducial registration and 0.76 +/- 0.24 mm at hybrid registration, and the target localization error was 1.34 +/- 0.32 mm at fiducial registration and 1.28 +/- 0.29 mm at hybrid registration. Of the 18 screws placed in the plastic bone models, one (6%) screw breached the pedicle wall. CONCLUSIONS: We have developed a robot arm-type three-dimensional digitizer-based navigation system for pedicle screw insertion, and found that its accuracy is equal or slightly better than that of optical tracker-based navigators.