A Comparative Study on the Influence of Probe Placement on Quality 
Assurance Measurements in B-mode Ultrasound by Means of Ultrasound 
Phantoms

To check or to prevent failures in ultrasound medical systems, some tests should be scheduled for both clinical suitability and technical functionality evaluation: among them, image quality assurance tests performed by technicians through ultrasound phantoms are widespread today and their results depend on issues related to scanner settings as well as phantom features and operator experience. In the present study variations on some features of the B-mode image were measured when the ultrasound probe is handled by the technician in a routine image quality test: ultrasound phantom images from two array transducers are processed to evaluate measurement dispersion in distance accuracy, high contrast spatial resolution and penetration depth when probe is handled by the operator. All measurements are done by means of an in-house image analysis software that minimizes errors due to operator’s visual acuity and subjective judgment while influences of ultrasound transducer position on quality assurance test results are estimated as expanded uncertainties on parameters above (measurement reproducibility at 95 percent confidence level): depending on the probe model, they ranged from ±0.1 to ±1.9 mm in high contrast spatial resolution, from ±0.1 to ±5.5 percent in distance measurements error and from ±1 to ±10 mm in maximum depth of signal visualization. Although numerical results are limited to the two examined probes, they confirm some predictions based on general working principles of diagnostic ultrasound systems: (a) measurements strongly depend on settings as well on phantoms features, probes and parameters investigated; (b) relative uncertainty due to probe manipulation on spatial resolution can be very high, i.e. from 10 to more than 30 percent; (c) Field of View settings must be taken into account for measurement reproducibility as well as Dynamic Range compression and phantom attenuation.

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Dual-source parallel radiofrequency excitation ACR phantom magnetic resonance imaging at 3 T: Assessment of the effect of image quality on high-contrast spatial resolution, percent signal ghosting, and low-contrast object detectability in comparison with conventional single-source transmission

Journal of the Korean Physical Society ◽

10.3938/jkps.63.1630 ◽

2013 ◽

Vol 63 (8) ◽

pp. 1630-1636

Author(s):

Kyung-Bae Lee ◽

Yong-Sung Park ◽

Bo-Young Choe

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Image Quality ◽

Spatial Resolution ◽

High Contrast ◽

Single Source ◽

Resonance Imaging ◽

Low Contrast ◽

Dual Source

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Estimation of contrast-to-noise ratio in CT and CBCT images with varying scan settings in presence of different implant materials

Dentomaxillofacial Radiology ◽

10.1259/dmfr.20190139 ◽

2019 ◽

Vol 48 (8) ◽

pp. 20190139

Author(s):

Emine Şebnem Kursun-Cakmak ◽

Husniye Demirturk Kocasarac ◽

Seval Bayrak ◽

Gülbahar Ustaoğlu ◽

Marcel Noujeim

Keyword(s):

Image Quality ◽

Imaging Modality ◽

Cone Beam Ct ◽

Medical Systems ◽

Plastic Container ◽

Implant Materials ◽

Different Types ◽

Noise Ratio ◽

Titanium Grade ◽

Imagej Software

Objectives: To assess the contrast-to-noise ratio (CNR) of four different types of dental implant materials in CT and cone beam CT (CBCT) images with varying scan settings. Methods: Four different types of implants: zirconium (Zr), titanium (Ti) Grade 4 and 5 and titanium–zirconium (Ti–ZrO2) alloy were placed in a 3% gelatin phantom in a cylindrical plastic container and scanned with two different CT machines (GE Medical systems and Toshiba Medical Systems) and one CBCT machine (I-CAT, Imaging Sciences International) with different voxel sizes of 0.2, 0.25, 0.3 and 0.4 mm. Images were analyzed using ImageJ software with the purpose of estimating the CNR. Results: The CNR obtained from images acquired with CT was lower than the CBCT with all voxel sizes tested. 0.3 and 0.4 mm voxel sizes exhibited the highest CNR (p < 0.05) that gives the best image quality. Among the implant materials tested, titanium Grade 5 has the highest levels of CNR while Zirconium has the lowest (p < 0.05). Conclusions: The optimum protocol for radiographic follow-up in areas near implants on the I-CAT is low-resolution settings (0.3 and 0.4 mm voxel sizes) which gave the highest CNR thus image quality. In presence of Zr implants, an alternative imaging modality (i.e., MRI) may be considered to avoid low-quality images.

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Efficacy of global dimming backlight and high-contrast liquid crystal panel for high-dynamic-range displays

Journal of the Society for Information Display ◽

10.1002/jsid.549 ◽

2017 ◽

Vol 25 (5) ◽

pp. 283-294 ◽

Cited By ~ 1

Author(s):

Mina Choi ◽

David M. Hoffman

Keyword(s):

Liquid Crystal ◽

Dynamic Range ◽

High Dynamic Range ◽

High Contrast ◽

High Dynamic ◽

Global Dimming ◽

Liquid Crystal Panel

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Using a NPWE model observer to assess suitable image quality for a digital mammography quality assurance programme

Radiation Protection Dosimetry ◽

10.1093/rpd/ncq010 ◽

2010 ◽

Vol 139 (1-3) ◽

pp. 459-462 ◽

Cited By ~ 4

Author(s):

P. Monnin ◽

F. O. Bochud ◽

F. R. Verdun

Keyword(s):

Quality Assurance ◽

Image Quality ◽

Digital Mammography ◽

Quality Assurance Programme ◽

Model Observer

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TREMOR: A Wireless MEMS Accelerograph for Dense Arrays

Earthquake Spectra ◽

10.1193/1.1856534 ◽

2005 ◽

Vol 21 (1) ◽

pp. 91-124 ◽

Cited By ~ 6

Author(s):

John R. Evans ◽

Robert H. Hamstra ◽

Christoph Kündig ◽

Patrick Camina ◽

John A. Rogers

Keyword(s):

Spatial Resolution ◽

Dynamic Range ◽

Strong Motion ◽

The United States ◽

Companion Paper ◽

Low Noise ◽

Practical Reasons ◽

Wireless Internet ◽

Urban Centers ◽

Strong Motion Network

The ability of a strong-motion network to resolve wavefields can be described on three axes: frequency, amplitude, and space. While the need for spatial resolution is apparent, for practical reasons that axis is often neglected. TREMOR is a MEMS-based accelerograph using wireless Internet to minimize lifecycle cost. TREMOR instruments can economically augment traditional ones, residing between them to improve spatial resolution. The TREMOR instrument described here has dynamic range of 96 dB between ±2 g, or 102 dB between ±4 g. It is linear to <1% of full scale (FS), with a response function effectively shaped electronically. We developed an economical, very low noise, accurate (<1%FS) temperature compensation method. Displacement is easily recovered to 10-cm accuracy at full bandwidth, and better with care. We deployed prototype instruments in Oakland, California, beginning in 1998, with 13 now at mean spacing of ∼3 km—one of the most densely instrumented urban centers in the United States. This array is among the quickest in returning (PGA, PGV, Sa) vectors to ShakeMap, ∼75 to 100 s. Some 13 events have been recorded. A ShakeMap and an example of spatial variability are shown. Extensive tests of the prototypes for a commercial instrument are described here and in a companion paper.

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Synthetic Aperture Imaging Using High-Frequency Convex Array for Ophthalmic Ultrasound Applications

Sensors ◽

10.3390/s21072275 ◽

2021 ◽

Vol 21 (7) ◽

pp. 2275

Author(s):

Hae Gyun Lim ◽

Hyung Ham Kim ◽

Changhan Yoon

Keyword(s):

Image Quality ◽

Penetration Depth ◽

Spatial Resolution ◽

High Frequency ◽

Imaging System ◽

Ex Vivo ◽

Synthetic Aperture ◽

Single Element ◽

High Frequency Ultrasound ◽

Synthetic Aperture Imaging

High-frequency ultrasound (HFUS) imaging has emerged as an essential tool for pre-clinical studies and clinical applications such as ophthalmic and dermatologic imaging. HFUS imaging systems based on array transducers capable of dynamic receive focusing have considerably improved the image quality in terms of spatial resolution and signal-to-noise ratio (SNR) compared to those by the single-element transducer-based one. However, the array system still suffers from low spatial resolution and SNR in out-of-focus regions, resulting in a blurred image and a limited penetration depth. In this paper, we present synthetic aperture imaging with a virtual source (SA-VS) for an ophthalmic application using a high-frequency convex array transducer. The performances of the SA-VS were evaluated with phantom and ex vivo experiments in comparison with the conventional dynamic receive focusing method. Pre-beamformed radio-frequency (RF) data from phantoms and excised bovine eye were acquired using a custom-built 64-channel imaging system. In the phantom experiments, the SA-VS method showed improved lateral resolution (>10%) and sidelobe level (>4.4 dB) compared to those by the conventional method. The SNR was also improved, resulting in an increased penetration depth: 16 mm and 23 mm for the conventional and SA-VS methods, respectively. Ex vivo images with the SA-VS showed improved image quality at the entire depth and visualized structures that were obscured by noise in conventional imaging.

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