National Electrical Manufacturers Association Standards Research Articles

Monte Carlo simulation of two Siemens Biograph PET/CT system using GATE: Image quality performance

The utilization of Monte Carlo simulation is a highly effective method in advancing research within the field of nuclear medicine. An important software tool for simulating and modeling cutting-edge systems for Positron Emission Tomography (PET) is the Geant4 Application for Tomographic Emission (GATE). This research specifically concentrates on two Siemens PET scanners: the Siemens Biograph True point (True V) and Siemens Biograph mcT 20 excel. Our primary objective was to validate the GATE V8.2 simulation in accordance with the NEMA (National Electrical Manufacturers Association) NU 2-2018 protocol, using a parallel computing platform on a local cluster of computers. This cluster was managed by the open-source package TORQUE version 6.1.0, which is based on the original wrapper PBS.The results of this validation process for the Siemens Biograph True point (True V) scanner were highly promising. The scatter fraction (SF), peak noise equivalent count rate (NECR), and sensitivity all demonstrated a remarkable level of agreement, with deviations within 10.02%, 5.4%, and 1.57%, respectively. Additionally, the spatial resolution was found to deviate by less than 0.59 mm. Image evaluations demonstrate high-quality results for both Siemens Biograph True point (True V) and Siemens Biograph mcT 20 excel scanners, validating the GATE simulation. The study on acquisition time provides insights into optimizing computing simulation time.This research demonstrates the effectiveness of Monte Carlo simulation, facilitated by GATE, in accurately modeling advanced PET systems. The validation results affirm the reliability of GATE V8.2 in accordance with NEMA standards for the Siemens Biograph True point (True V) scanner. The high-quality images obtained from GATE-validated scanners underscore the potential of this simulation approach in advancing nuclear medicine research. Additionally, the study on acquisition time provides valuable considerations for optimizing simulation efficiency.

Performance Comparison Between Two-Level and Three-Level SiC-Based VFD Applications With Output Filters

One of the recent trends in power electronics field is to achieve high efficiency and compact size by using wide bandgap power devices such as silicon carbide (SiC) or gallium nitride switches. This paper compares the efficiency, the motor terminal voltage quality ( dv/dt ), and the common mode current of the SiC-based variable frequency drives (VFDs) according to the inverter topologies with and without the output filters. For this purpose, both the 2-level (2L) and 3-level (3L) topologies with SiC devices are built and tested. Here, the well-known 2L half-bridge inverter is compared with the well-known 3L T-type neutral point clamped inverter. A dv/dt filter and a sine wave filter have been discussed to satisfy the National Electrical Manufacturers Association standards as well. The experiments have been carried out with a 380-V/60-Hz, 3.7-kW induction motor and the custom designed power stages. Additionally, the experiments with both a 3-m and a 50-m cable length between the VFD and the induction motor are performed and reported.

Standardization of image quality across multiple centers by optimization of acquisition and reconstruction parameters with interim FDG-PET/CT for evaluating diffuse large B cell lymphoma

A multicenter trial is currently underway using FDG-PET/CT to evaluate diffuse large B cell lymphoma in Japan (JSCT NHL10). Standardization of the image quality between the participating centers is a fundamental aspect of the study. Within the framework of JSCT NHL10, standardization of the image quality was attempted by optimizing the acquisition and reconstruction conditions using mid-therapy FDG-PET/CT for diffuse large B cell lymphoma. This report describes the procedures and results of this attempt. The acquisition protocols and imaging quality were initially determined at each center and again after modification. The image quality was based on performance with an (18)F-filled National Electrical Manufacturers Association standards body phantom. We determined that the acquisition duration and reconstruction parameters of each scanner evaluated were in compliance with the Japanese guideline for the oncology FDG-PET/CT data acquisition protocol: synopsis of Version 1.0 (the Guideline) based on the results of the phantom experiments performed by the Core Laboratory. A total of 18 centers (19 scanners) participated in this trial. The center's default protocol was unchanged for 9 scanners (47.4%) and changed for 10 scanners (52.6%). Both acquisition duration and reconstruction parameters were changed in 3 (15.8%) of 10 scanners and the acquisition duration alone was changed in 7 (36.8%) scanners. Also, the accuracy of the standardized uptake value (SUV) was evaluated with the acceptable level 1.0 ± 0.1, resulting in readjustment and recalibration in 2 scanners (10.5%), which were confirmed to attain the acceptable accuracy after the required readjustment. As of August 2012, 21 patients have undergone an FDG-PET/CT examination under the acquisition protocols determined by the Core Laboratory. Evaluation of the image quality using several physical parameters confirmed that the accumulated data were of sufficient quality. Optimization of the acquisition protocol, in compliance with the guideline, was successfully achieved by the Core Laboratory in the framework of JSCT NHL10 to accumulate equivalent quality data across multiple centers. The progress of the trial was greatly facilitated by support from the Japan Society of Nuclear Medicine Working Group for Investigation of Response Evaluation Criteria in Malignant Tumors Using Standardized PET/CT (Principal Investigator: Ukihide Tateishi, MD., PhD).

Comparison of the Performance Evaluation of the MicroPET R4 Scanner According to NEMA Standards NU 4-2008 and NU 2-2001

The purpose of this work was to evaluate the performance of the microPET R4 system for rodents according to the NU 4-2008 standards of the National Electrical Manufacturers Association (NEMA) for small-animal positron emission tomography (PET) systems and to compare it against its previous evaluation according the adapted clinical NEMA NU 2-2001. The performance parameters evaluated here were spatial resolution, sensitivity, scatter fraction, counting rates for rat- and mouse-sized phantoms, and image quality. Spatial resolution and sensitivity were measured with a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">22</sup> Na point source, while scatter fraction and count rate performance were determined using a mouse and rat phantoms with an <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> F line source. The image quality of the system was assessed using the NEMA image quality phantom. Assessment of attenuation correction was performed using γ-ray transmission and computed tomography (CT)-based attenuation correction methods. At the center of the field of view, a spatial resolution of 2.12 mm at full width at half maximum (FWHM) (radial), 2.66 mm FWHM (tangential), and 2.23 mm FWHM (axial) was measured. The absolute sensitivity was found to be 1.9% at the center of the scanner. Scatter fraction for mouse-sized phantoms was 8.5 %, and the peak count rate was 311 kcps at 153.5 MBq. The rat scatter fraction was 22%, and the peak count rate was 117 kcps at 123.24 MBq. Image uniformity showed better results with 2-D filtered back projection (FBP), while an overestimation of the recovery coefficients was observed when using 2-D and 3-D OSEM MAP reconstruction algorithm. All measurements were made for an energy window of 350-650 keV and a coincidence window of 6 ns. Histogramming and reconstruction parameters were used according to the manufacturer's recommendations. The microPET R4 scanner was fully characterized according to the NEMA NU 4-2008 standards. Our results diverge considerably from those previously reported with an adapted version of the NEMA NU 2-2001 clinical standards. These discrepancies can be attributed to the modifications in NEMA methodology, thereby highlighting the relevance of specific small-animal standards for the performance evaluation of PET systems.

Design and evaluation of the MAMMI dedicated breast PET

A breast dedicated positron emission tomography (PET) scanner has been developed based on monolithic LYSO crystals coupled to position sensitive photomultiplier tubes (PSPMTs). In this study, we describe the design of the PET system and report on its performance evaluation. MAMMI is a breast PET scanner based on monolithic LYSO crystals. It consists of 12 compact modules with a transaxial field of view (FOV) of 170 mm in diameter and 40 mm axial FOV that translates to cover up to 170 mm. The patient lies down in a prone position that facilitates maximum breast elongation. Quantitative performance analysis of the calculated method for the attenuation correction specifically developed for MAMMI, and based on PET image segmentation, has also been conducted in this evaluation. In order to fully determine the MAMMI prototype's performance, we have adapted the measurements suggested for National Electrical Manufacturers Association (NEMA) NU 2-2007 and NU 4-2008 protocol tests, as they are defined for whole-body and small animal PET scanners, respectively. Spatial resolutions of 1.6, 1.8, and 1.9 mm were measured in the axial, radial, and tangential directions, respectively. A scatter fraction of 20.8% was obtained and the maximum NEC was determined to be 25 kcps at 44 MBq. The average sensitivity of the system was observed to be 1% for an energy window of (250 keV-750 keV) and a maximum absolute sensitivity of 1.8% was measured at the FOV center. The overall performance of the MAMMI reported on this evaluation quantifies its ability to produce high quality PET images. Spatial resolution values below 3 mm were measured in most of the FOV. Only the radial component of spatial resolution exceeds the 3 mm at radial positions larger than 60 mm. This study emphasizes the need for standardized testing methodologies for dedicated breast PET systems similar to NEMA standards for whole-body and small animal PET scanners.

Performance evaluation for pinhole collimators of small gamma camera by MTF and NNPS analysis: Monte Carlo simulation study

Presently, the gamma camera system is widely used in various medical diagnostic, industrial and environmental fields. Hence, the quantitative and effective evaluation of its imaging performance is essential for design and quality assurance. The National Electrical Manufacturers Association (NEMA) standards for gamma camera evaluation are insufficient to perform sensitive evaluation. In this study, modulation transfer function (MTF) and normalized noise power spectrum (NNPS) will be suggested to evaluate the performance of small gamma camera with changeable pinhole collimators using Monte Carlo simulation. We simulated the system with a cylinder and a disk source, and seven different pinhole collimators from 1- to 4-mm-diameter pinhole with lead. The MTF and NNPS data were obtained from output images and were compared with full-width at half-maximum (FWHM), sensitivity and differential uniformity. In the result, we found that MTF and NNPS are effective and novel standards to evaluate imaging performance of gamma cameras instead of conventional NEMA standards.

Comparison of international and NEMA standards for salient pole synchronous machines

The Electrical Machinery Committee (EMC) of the Power Engineering Society (PES) of the Institute of Electrical and Electronics Engineers (IEEE) has established a task force charged with the review and comparison of US Standards with international standards with a view to harmonizing these standards. This paper is in response to an assignment from that Task Force. It compares IEC 34 series of standards with National Electrical Manufacturers Association (NEMA) standards for salient pole synchronous machines for nonhydro applications.

IEC and NEMA standards for large squirrel-cage induction motors-a comparison

The Electrical Machinery Committee (EMC) of the Power Engineering Society (PES) of the Institute of Electrical and Electronics Engineers (IEEE) has established a Task Force charged with the review and comparison of US standards with International Standards and to see if harmonization was possible. This paper is in response to an assignment from that Task Force. It compares IEC 34 series of standards with National Electrical Manufacturers Association (NEMA) standards for large induction motors for general purpose applications.

New oil-filled apparatus bushings

FOR 32 YEARS, oil-filled bushings have been applied to transformers and oil circuit breakers. Although these bushings have an excellent service record, recent trends in electric apparatus have made improvements necessary. A new line of oil-filled bushings has been developed which meets the requirements of hermetic sealing, low-cost maintenance, high mechanical strength, reduction in size and weight, and also provides ease of installation and storage. These bushings meet AIEE and NEMA (National Electrical Manufacturers Association) standards and are designed to meet the needs of modern apparatus.